Complete Spectroscopy of Water: Experiment and Theory
INTAS grant 03-51-3394
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Полная спектроскопия воды: Эксперимент и теория
OBJECTIVES
RESEARCH OBJECTIVES
The overall objective of the proposal is to provide a comprehensive solution to the problem of the rotation-vibration spectrum of water. This solution will embrace both high quality experimental measurements and sophisticated theoretical models. To achieve this goal a number specific scientific objectives will be addressed:
To analyze Fourier Transform (FT) spectrum of water vapour at room temperature from the infrared to the ultraviolet region, 9000 - 26000 cm-1, (over 16000 lines).
To measure the water vapour high temperature absorption spectra (up to T=800 K) in the region of 10000 - 16000 cm-1, the emission spectra of oxygen-hydrogen flame (T=2000 K) in the region 10000 - 16000 cm-1.
To analyze flame emission spectra (T=3000 K) in the 600 - 13000 cm-1 region (over 50000 lines), sun spot absorption spectra 400-8000 cm-1 (over 10000 lines), D2O emission laboratory spectrum, 400-8000 cm-1, 1800 K (over 45000 lines).
To obtain the absorption spectrum of extremely weak transitions of HDO. To obtain the line positions and intensities of H2O in spectral windows corresponding to extremely weak transitions (1.5-1.6 micron and 1.0-1.1 micron).
To obtain new energy levels of water molecule and its isotopomers from the analysis experimental data.
To improve ab initio potential energy surface (PES) and dipole moment surface (DMS) by extending previous ultra-high accuracy calculations, by performing better treatment of corrections to Born-Oppenheimer (BO) approximation and increasing the level of electronic structure theory.
To create theoretical models within the Effective Hamiltonian (EH) and Effective Dipole Moment (EDM) approaches which are able to predict all the H2O and H2S vibration-rotation transitions within the ground electronic state.
To obtain new data on line intensities, N2 and air broadening and shifting. To model pressure broadening and pressure shifts taking into account strong excitation effects. To use these data to study the H2O line broadening and shifting under strong excitation and to create the databases for various applications.
To fit ab initio PES using existing and new experimental energy levels which give levels with an accuracy close to 0.01 cm-1 (the average experimental accuracy).
To compile new line lists based on both variational calculations and more accurate EH calculations. To create a new database of H2O, and possibly H2S, experimental energy levels.
To prepare new experimental and theoretical data for inclusion to present spectroscopic databases (HITRAN, GEISA...) and to distribute this data using appropriate means such as the World Wide Web.
Background and Justification
The spectrum of water is arguably the single most important spectrum of any molecule. Therefore many years of work, both experimental and theoretical, have been devoted to trying to both catalogue and understand this spectrum. Despite these efforts, short-wavelength (near infrared, visible and even near ultraviolet) spectra which probe highly excited vibrational states and high temperature spectra, which also probe highly excited rotational states remain poorly characterised.
These spectra are of vital importance for a range of applications including atmospheric transmission, combustion modelling and astrophysical applications such the atmosphere of dwarf stars and even sunspots. Modellers rely on data bases of transitions (line positions, intensity, assignments and pressure-dependent parameters). Typical atmospheric databases contain over 30,000 transitions due to water. Recent theoreticallydriven attempts to solve all aspects of the water spectroscopy problem have produced data bases with approaching a billion transitions. So far none of these huge data bases offer the required accuracy.
Recent years have seen major advances in water spectroscopy driven experimentally by the use of lasers to give ultra-long path-lengths and therefore, in principle, very high sensitivity. On the theoretical side, the use of variational calculations has revolutionised the taxing problem of assigning the spectra involving highly excited states, an essential step for applications using this data. Furthermore, recent advances in ab initio theory, breaching the 1 cm-1 accuracy barrier for water for the first time, raise the real possibility that accurate spectra could be calculated using first principles quantum mechanics.
Application of these methods has led to numerous experimental and theoretical studies of water spectra. Thousands of new energy levels have been obtained experimentally. Overall these have led to an increase in the number of known experimentally energy levels by a factor of about three and a similar increase in the assigned transitions. Despite this work, there remains significant problem with the spectrum of water: many spectra remain poorly analyzed, for example only 15% of the transitions observed in sunspots actually have quantum number assignments. The incompleteness of our knowledge of water spectra has significant practical consequences: for example the exact contribution of absorptions by water vapour to the earth’s energy budget remains a subject of debate and the analysis of data obtained from earth remote sensing experiments on board satellites such as ENVISAT is severely hampered by the uncertainties in the laboratory data for water. There is thus the utmost need for a coordinate attack on the spectroscopy of water which combines both high class theory and state-of-the-art laboratory work.
This proposal aims to provide a comprehensive solution to the rotation-vibration spectrum of water by combining world-leading laboratories that specialise in the measurement, calculation and analysis of the spectra of small molecules and in particular water. To do this it is necessary to characterize line positions, intensities, assignments and behaviour under different physical conditions (temperature and pressure). This goal requires thorough experimental coverage of key spectral regions which can be used to validate high accuracy ab initio and semiempirical models. A major deliverable will be the provision comprehensive data on water spectra for use by modellers.
To achieve these aims the complementary theoretical approaches will be employed: semiempirical and ab initio. Semiempirical methods are capable, in principle, of achieving experimental accuracy. These methods use either variational calculations based on potential surfaces fitted to spectroscopic energies or effective Hamiltonians expansions. As yet ab initio approaches do not give this accuracy but are important as they are complete (i.e. can probe all wavelengths and even transitions of vanishingly small intensity), are used to seed the semiempircal fits and provide accurate dipole surfaces which are necessary to generate line intensities.
This proposal combines the efforts of laboratories, which have made a major contribution to the development of theoretical and experimental studies of water spectra. They will deliver a comprehensive solution to the water spectral problem which has many important uses. Application of the methods developed to related triatomic molecules such as H2S will also be explored.
The participating teams have immense experience developing spectroscopic experimental and theoretical methods and applying them for measuring and analyzing molecular spectra. Highly sensitive intracavity laser spectrometers were developed and used for weak line investigations in 70-90s in Institute of Atmospheric Optics (IAO team). Since 1972, when the team had began to build up such spectrometers there is a continuing work in the field, and the team has published first monographs in this subject in Russian and English , [1]. These spectrometers allowed recording of many weak lines of H2O, CO2, C2H2, CH4, and their isotopomers in the spectral region higher 8000 cm-1. At the present highly sensitive laser spectrometers are widely used in the IAO for study of molecules at high excitation (at high temperature, in flame, in discharge); and new type of spectrophotometric gas analyzers are being developing for atmospheric tasks.
In the University Joseph Fourier of Grenoble, France (UNIJFG team) a number of ultra sensitive absorption laser techniques were developed in recent years, including Intracavity Laser Absorption Spectroscopy, Cavity-Ring Down Spectroscopy, Cavity Enhanced Absorption Spectroscopy [2], [3]. The investigated molecules include water, acetylene, hydrogen sulfur, methane, silanes and their isotopic derivatives. The higher sensitivity of UNIJFG methods in comparison with say Fourier Transform Spectroscopy methods allows for a considerable increase of the number of observed weak lines.
Until recent years the main theoretical method of analyzing spectra of water and related molecules were Effective Hamiltonian (EH) approach. The theoreticians from IAO team since 80-s are taking part in development of models within the EH and Effective Dipole Moment (EDM) approaches. This work was done in parallel with analyzing experimental spectra with results published in tens of papers [4]. The team from Institute of Applied Physics of Russian Academy of Sciences (IAP team) also has long and successful history in studying light molecules. First theoretical works studying water spectrum were published in early 80-s. Originally the analysis was done using Effective Hamiltonian approach. Leader of the IAP team O.L. Polyansky in 1985 proposed Pade-Borel method of EH series summation [5] since then widely used for studying water and related molecules spectra.
Since early 90-s progress in development of computational hardware and ‘software’ lead to variational calculations taking the bigger part in analyzing spectra of triatomic molecules. In particular the program suit DVR3D [[6]] for variational calculations of vibration-rotation energy levels using the exact kinetic energy operator for nuclear motion was developed in the University College London, UK (UCL). The accuracy of variational calculations is mostly determined by the quality of potential energy surface (PES). The UCL and IAP teams had developed semiemperical PESes for H2O and H2S which were the best at the time [7], [8]. The difficulties in getting spectroscopic accuracy (0.01 cm-1) with variational calculations meant that it was necessary to take into consideration corrections to Born-Oppenheimer (BO) surface. In 1997 H. Partridge and D.W. Schwenke calculated ab initio PES of water (J. Chem. Phys., 106, 4618 (1997)) with highest for the time accuracy. They also optimized the ab initio surface to get semiempirical PES with standard deviation of about 0.1 cm-1 for energy levels included in the fitting. Adding of adiabatic correction to the surface allowed IAP team in cooperation with UCL to start analyzing complicated experimental spectra of water. In particular the absorption spectra of sun spots were studied [9].
In cooperation of IAP, UCL and team from Eotvos Lorand University, Hungary (ELTE) electronic relativistic and quantum electrodynamics corrections to BO PES of water were calculated [10], giving significant improvement in theoretical predictions. In parallel with development of theoretical calculations methods UCL and IAP analyzed a number of spectra of H2O and it’s isotopomers, including sun spot spectra (T=3300 K), room temperature spectra in 9000 – 26000 cm-1 region, hot (T=1800 K) emission laboratory spectra. Tens of thousands of lines were analyzed and assigned. This leaded to doubling of the number of observed energy levels of water molecule from about 6000 to 12000. The new compilation of energy levels was published in [11]. Using of corrections to BO surface and newly determined energy levels allowed IPF and UCL teams to optimize PS ab initio PES to get semiemperical potential with 0.1 cm-1 standard deviation for almost all known energy levels [12] of H216O.
In cooperation of ELTE, UCL and IAP teams very elaborate non-relativistic electronic structure calculations of water were performed, also considering a variety of small physical effects arising from a fully relativistic treatment, breakdown of the BO approximation, and even quantum electrodynamics. The result was ab initio PES of water determining the vibration-rotation energy level structure to better than 1 cm-1 on average [13]. Ab initio improvements of this PES with it’s optimization using now known and obtained during the project energy levels should lead to determining of semiempirical PES with about 0.01 cm-1 accuracy.
The problem of calculating line intensities is much less developed then that of line frequencies. The calculations of dipole moments converge differently from those of energies. Empirical DMSs rely on absolute spectroscopic intensity measurements, which are notoriously difficult to carry out with high accuracy. In [14] dipole moments of highly vibrationally excited water were measured for the first time and calculated by ELTE, UCL and IAP teams. The calculations suggested that the best currently available potential and dipole surfaces do not accurately model intensities in the optical spectrum of water. The IAO and UNIJFG teams have a long experience of experimental studies of transition intensities and pressure effects on lineshape. IAO team developed a number of methods using Effective Dipole Moments for its modelling.
Semiempirical methods of using experimental data for calculations of energy levels and intensities open possibility of obtaining results with experimental accuracy. EH methods give better accuracy but for limited spectral regions while variational calculations can provide overall outline of whole water spectrum. Their combination in one project gives unique opportunity to solve the problem of high resolution water spectrum.
The project teams publications:
Литература:
Sinitsa L.N,
Encyclopedia of Optical Engineering.,
(EOE). Published by Markel Dekker, Inc. No 120009765, 1990.
Bertseva E., A. Kachanov and A. Campargue,
Intracavity laser absorption spectroscopy of N2O with a vertical external cavity surface emitting laser,
Chemical Physics Letters, 2002, Volume 351, Issue 1-2, Pages 18-26,
DOI: 10.1016/S0009-2614(01)01321-5.
Annotation
The Intracavity Laser Absorption Spectrum (ICLAS) of nitrous oxide, (12)N2(16)O, has been recorded between 9560 and 9980 cm-1 with a Vertical External Cavity Surface Emitting Laser (VECSEL). Thirteen bands were observed, 11 of which are new. The rovibrational analysis has revealed the occurrence of a number of local perturbations due to anharmonic or Coriolis couplings, which could be analysed on the basis of the polyad model of effective Hamiltonian.
Chemical Physics Letters publishes brief reports of original research on the structures, properties and dynamics of molecules, solid surfaces, interfaces, condensed phases, polymers, nanostructures and biomolecular systems.
Criteria for publication are quality, urgency and impact. Further, experimental results reported in the journal have direct relevance for theory, and theoretical developments or non-routine computations relate directly to experiment.
Manuscripts must satisfy these criteria and should not be minor extensions of previous work or just descriptions of the synthesis of molecules or materials.
As the world’s leading publisher of science and health information, Elsevier serves more than 30 million scientists, students, and health and information professionals worldwide.
We are proud to play an essential role in the global science and health communities and to contribute to the advancement of these critical fields. By delivering world-class information and innovative tools to researchers, students, educators and practitioners worldwide, we help them increase their productivity and effectiveness. We continuously make substantial investments that serve the needs of the global science and health communities.
Ding Y., O. Naumenko, S-M. Hu, E. Bertseva, and A. Campargue,
The absorption spectrum of H2S between 9540 and 10 000 cm-1 by intracavity laser absorption spectroscopy with a vertical external cavity surface emitting laser,
Journal of Molecular Spectroscopy, 2003, Volume 217, Issue 2, Pages 222-238,
DOI: 10.1016/S0022-2852(02)00037-1.
Annotation
An Intracavity Laser Absorption Spectrometer (ICLAS) based on a Vertical External Cavity Surface Emitting Laser (VECSEL) has been used to record the absorption spectrum of H2S between 9540 and 10 000 cm-1 with pressures up to 122 Torr (160.5 hPa) and equivalent absorption path lengths up to 45 km. More than 1600 absorption lines were attributed to the transitions reaching the highly excited (40±,0), (30±,2), and (11+,4) states (local mode notation). The existing information relative to the (40±,0) local mode bright pair at 9911.02 cm-1 was considerably enlarged, while the other states are reported for the first time. Eight hundred and ninety two precise energy levels were derived, including 181 and 28 levels for the H234S and H233S minor isotopomers, respectively. These energy levels were fitted using a Watson-type rotational Hamiltonian and the spectroscopic parameters were obtained, yielding an rms deviation of 0.006 cm-1 for the H232S species-close to the experimental accuracy. The dark states-(20+,4) and (11+,4)-at 9647.77 and 9744.88 cm-1, respectively, were found to perturb the observed energy levels and were then included into the final energy levels modeling. The (40±,0) states are very close to the local mode limit, i.e., with a mostly identical rotational structure. The (30±,2) states are separated by 0.077 cm-1 and this separation holds for most of the rotational sublevels. The resonance interactions between the three local mode pairs-(40±,0), (30±,2), and (20±,4)-and the (11+,4) state affect in some cases specifically one of the component of the pair and then the energy separation of the corresponding near degenerate rotational levels. Line intensities were obtained on the basis of the relative intensities measured by ICLAS and from absolute values of the stronger lines measured separately by Fourier Transform Spectroscopy associated with a multipass cell. The transition intensities could be successfully modeled and the integrated band intensities are given and discussed.
The Journal of Molecular Spectroscopy presents experimental and theoretical articles on all subjects relevant to molecular spectroscopy and its modern applications. An international medium for the publication of some of the most significant research in the field, the Journal of Molecular Spectroscopy is an invaluable resource for astrophysicists, chemists, physicists, engineers, and others involved in molecular spectroscopy research and practice. Submit your Article online
The 'Elsevier Editorial System' (or EES) is a web-based system with full online submission, review and status update capabilities. EES allows you to upload files directly from your computer. This is part of our on-going efforts to improve the efficiency and accuracy of our editorial procedures and the quality and timeliness of the manuscripts published.
As the world’s leading publisher of science and health information, Elsevier serves more than 30 million scientists, students, and health and information professionals worldwide.
We are proud to play an essential role in the global science and health communities and to contribute to the advancement of these critical fields. By delivering world-class information and innovative tools to researchers, students, educators and practitioners worldwide, we help them increase their productivity and effectiveness. We continuously make substantial investments that serve the needs of the global science and health communities.
Bykov A., O.Naumenko, A.M.Pshenichnikov, A.Scherbakov, and L.Sinitsa,
Expert System for line identifications in rovibrational spectra,
Optics and Spectroscopy, 2003, Volume 94, no. 4, Pages 528-537,
DOI: 10.1134/1.1570477.
Annotation
An expert system for automatic identification of the complex vibrational-rotational spectra of molecules has been developed. An iteration approach is implemented in this system, in which employment of the exact combination rule is combined with determination of the spectroscopic constants by solving of the inverse problems and comparison of the calculated parameters of spectral lines with the corresponding measured values. In order to calculate the energy levels and the frequencies and intensities of lines, the Watson Hamiltonian, the Padé-Borel approximants, and generating functions are used. The system is based on the application of pattern-recognition algorithms. Recognition training makes it possible to obtain the required flexibility of the system and to use different methods of identification based on the application of combination rules both for the analysis of strong bands and for the assignment of weak single lines. The system developed can be used to analyze the spectra of the Cs and C2V molecules, as well as employ the calculated spectrum of a molecule of any type prepared in advance. This system was successfully used to identify the H 216 O, H 217 O, H 218 O, D2O, HDO, H 232 S, H 234 S, and H 233 S and molecules.
Optics and Spectroscopy (Optika i spektroskopiya), founded in 1956, presents original and review papers in various fields of modern optics and spectroscopy in the entire wavelength range from radio waves to X-rays. Coverage includes problems of theoretical and experimental spectroscopy of atoms, molecules, and condensed state, lasers and the interaction of laser radiation with matter, physical and geometrical optics, holography and physical principles of optical instrument making.
O.L. Polyansky,
One-dimensional approximation of the effective rotational Hamiltonian of the ground state of the water molecule,
Journal of Molecular Spectroscopy, 1985, Volume 112, Issue 1, Pages 79-87,
DOI: 10.1016/0022-2852(85)90193-6.
Annotation
A method is presented for summation of the divergent perturbation-theory series used in molecular spectroscopy, by means of a one-dimensional approximation. Application of the proposed method enables one to fit the energy levels of the ground state of the water molecule (Mol. Phys. 32, 499-521 (1976)) to a maximum difference between the observed and the calculated levels of less than 8 cm-1 for levels with the maximum rotational quantum numbers K = 20 and J = 20 in a model with 24 parameters and terms up to J8.
The Journal of Molecular Spectroscopy presents experimental and theoretical articles on all subjects relevant to molecular spectroscopy and its modern applications. An international medium for the publication of some of the most significant research in the field, the Journal of Molecular Spectroscopy is an invaluable resource for astrophysicists, chemists, physicists, engineers, and others involved in molecular spectroscopy research and practice. Submit your Article online
The 'Elsevier Editorial System' (or EES) is a web-based system with full online submission, review and status update capabilities. EES allows you to upload files directly from your computer. This is part of our on-going efforts to improve the efficiency and accuracy of our editorial procedures and the quality and timeliness of the manuscripts published.
As the world’s leading publisher of science and health information, Elsevier serves more than 30 million scientists, students, and health and information professionals worldwide.
We are proud to play an essential role in the global science and health communities and to contribute to the advancement of these critical fields. By delivering world-class information and innovative tools to researchers, students, educators and practitioners worldwide, we help them increase their productivity and effectiveness. We continuously make substantial investments that serve the needs of the global science and health communities.
Tennyson, J.R. Henderson and N.G. Fulton,
DVR3D: for the fully pointwise calculation of ro-vibrational spectra of triatomic molecules,
Computer Physics Communications, 1995, Volume 86, Issue 1, Pages 175-198,
DOI: 10.1016/0010-4655(94)00139-S.
Annotation
The DVR3D program suite calculates energy levels, wavefunctions, and where appropriate dipole transition moments, for rotating and vibrating triatomic molecules. Potential energy, and where necessary, dipole surfaces must be provided. The programs use an exact (within the Born-Oppenheimer approximation) Hamiltonian, offer a choice of Jacobi or Radau internal coordinates and several body-fixed axes. Rotationally excited states are treated using an efficient two-step algorithm. The programs uses a Discrete Variable Representation (DVR) based on Gauss-Legendre and Gauss-Laguerre quadrature for all 3 internal coordinates and thus yields a fully pointwise representation of the wavefunctions. The vibrational step uses successive diagonalisation and truncation which is implemented for 4 of the 6 possible coordinate orderings. The rotational and transition dipole programs exploit the major savings offered by performing integrals on a DVR grid.
Computer Physics Communications publishes research papers and computer program descriptions in computational physics and physical chemistry: the focus is on computational methods and techniques rather than results. All contributions are peer reviewed. Special issues are published on an occasional basis; enquiries should be directed to a member of the Editorial Board. Some papers describe computer programs that are deposited in the CPC Program Library which, with over 2,000 programs contributed since 1969, is a major computational resource for the community. Programs are available at http://cpc.cs.qub.ac.uk and are free to members of institutions with an institutional journal subscription.
Articles cover:
computational models and programs in physics and physical chemistry;
computational models and programs associated with the design, control and analysis of experiments;
numerical methods and algorithms;
algebraic computation;
the impact of advanced computer architecture and special purpose computers on computing in the physical sciences; and
As the world’s leading publisher of science and health information, Elsevier serves more than 30 million scientists, students, and health and information professionals worldwide.
We are proud to play an essential role in the global science and health communities and to contribute to the advancement of these critical fields. By delivering world-class information and innovative tools to researchers, students, educators and practitioners worldwide, we help them increase their productivity and effectiveness. We continuously make substantial investments that serve the needs of the global science and health communities.
Polyansky O.L., P. Jensen and J. Tennyson, J,
A spectroscopically determined potential energy surface for the ground state of H216O: A new level of accuracy,
Journal of Chemical Physics, 1994, Volume 101, Pages 7651-7657,
DOI: 10.1063/1.468258.
Annotation
The potential energy function for the electronic ground state of the water molecule has been obtained by fitting rotation-vibration term values involving J=<14 for 24 vibrational states of H216O together with 25 additional vibrational term values belonging to higher excited states. The fitting was carried out by means of an exact kinetic energy Hamiltonian. It was found that the differences between the exact kinetic energy calculations and calculations with the morbid program (i.e., calculations with an approximate kinetic energy operator) depend only very slightly on the parameters of the potential. This fact allowed us to make an inexpensive fitting using the morbid approach and still get the accuracy obtainable with the exact kinetic energy Hamiltonian. The standard deviation for 1600 term values was 0.36 cm-1. For 220 ground state energy levels the standard deviation was 0.03 cm-1. With the fitted potential, calculations of term values with J<=35 were carried out. This showed the excellent predictive power of the new potential. For the J=20 term values in the vibrational ground state, the deviations from experiment are typically below 0.2 cm-1. The discrepancy for the observed level with the highest Ka value, JKaKc = 20200, is only 0.008 cm-1. The calculated term value for the observed level with the highest J, 35035, deviates 0.1 cm-1 from experiment. Because of the level of accuracy achieved in these calculations, we can for the first time demonstrate the breakdown of the Born–Oppenheimer approximation for the water molecule. The high Ka level calculations allow us to show that the rotational energy level structure in water is at least of a very different nature than the fourfold cluster structures observed for H2Se and calculated for H2S, H2Se, and H2Te.
Journal
The Journal of Chemical Physics [J. Chem. Phys.], American Institute of Physics,
ISSN: 0021-9606, http://ojps.aip.org/jcpo/.
The purpose of The Journal of Chemical Physics is to bridge a gap between journals of physics and journals of chemistry by publishing quantitative research based on physical principles and techniques, as applied to "chemical" systems. Just as the fields of chemistry and physics have expanded, so have chemical physics subject areas, which include polymers, materials, surfaces/interfaces, and biological macromolecules, along with the traditional small molecule and condensed phase systems. The Journal of Chemical Physics (JCP) is published four times per month (48 issues per year) by the American Institute of Physics.
The American Institute of Physics (AIP) is a 501(c)(3) not-for-profit membership corporation created for the purpose of promoting the advancement and diffusion of the knowledge of physics and its application to human welfare. It is the mission of the Institute to serve the sciences of physics and astronomy by serving its member societies, by serving individual scientists, and by serving students and the general public.
We report here a new determination of the H216O potential energy surface from experimental data. The calculations have been carried out by means of the very accurate and highly efficient method proposed and applied to H216O in a previous paper [Polyansky, Jensen, and Tennyson, J. Chem. Phys. 101, 7651 (1994)]. This previous work has been significantly improved by inclusion of additional terms in the analytical expression used to represent the potential energy surface. Previously, 1600 rotation-vibration term values for H216O were fitted with a standard deviation of 0.36 cm-1. With the extended model of the present work, this standard deviation could be improved to 0.25 cm-1. With the extended model and the new fitted potential function we have calculated a data set comprising 3200 term values, all of which can be compared with experimentally derived values. The standard deviation for this data set is 0.6 cm-1. The data set contains rotationally excited energy levels for all the 63 vibrational states which have been characterized by high resolution spectroscopy. The potential energy function obtained in the present work improves drastically the agreement with experiment for the highly excited local mode stretching states above 20 000 cm-1. For the vibrational band origins of these states, the highest of which is measured at 25 118 cm-1, our previous fitted potential produced discrepancies of more than 100 cm-1. These deviations are reduced to less than 1 cm-1 by the potential energy function of the present work. We show that no significant improvement of the fit can be obtained by extending the analytical expression for the potential energy by further high-order terms. An analysis of the residuals shows that at the level of accuracy achieved, the major contribution to the error originates in the neglect of nonadiabatic correction terms in the Born-Oppenheimer kinetic energy operator. We conclude that any further improvement of the potential energy surface requires that such correction terms be included in the Hamiltonian. With the present potential, reliable extrapolations towards higher rotational and vibrational energies can be carried out, and we expect that such calculations can be very helpful in the assignment of experimental spectra involving highly excited states.
Journal
The Journal of Chemical Physics [J. Chem. Phys.], American Institute of Physics,
ISSN: 0021-9606, http://ojps.aip.org/jcpo/.
The purpose of The Journal of Chemical Physics is to bridge a gap between journals of physics and journals of chemistry by publishing quantitative research based on physical principles and techniques, as applied to "chemical" systems. Just as the fields of chemistry and physics have expanded, so have chemical physics subject areas, which include polymers, materials, surfaces/interfaces, and biological macromolecules, along with the traditional small molecule and condensed phase systems. The Journal of Chemical Physics (JCP) is published four times per month (48 issues per year) by the American Institute of Physics.
The American Institute of Physics (AIP) is a 501(c)(3) not-for-profit membership corporation created for the purpose of promoting the advancement and diffusion of the knowledge of physics and its application to human welfare. It is the mission of the Institute to serve the sciences of physics and astronomy by serving its member societies, by serving individual scientists, and by serving students and the general public.
Polyansky O.L., N.F. Zobov, J. Tennyson, S. Viti, P.F. Bernath and L. Wallace,
Water on the Sun: Line Assignments Based on Variational Calculations,
Science, 1997, Volume 277, no. 5324, Pages 346-348 DOI: 10., http://www.sciencemag.org.
Annotation
The infrared spectrum of hot water observed in a sunspot has been assigned. The high temperature of the sunspot (3200 K) gave rise to a highly congested pure rotational spectrum in the 10-micrometer region that involved energy levels at least halfway to dissociation. Traditional spectroscopy, based on perturbation theory, is inadequate for this problem. Instead, accurate variational solutions of the vibration-rotation Schrцdinger equation were used to make assignments, revealing unexpected features, including rotational difference bands and fewer degeneracies than anticipated. These results indicate that a shift away from perturbation theory to first principles calculations is necessary in order to assign spectra of hot polyatomic molecules such as water.
Journal
Science [Science], The American Association for the Advancement of Science, www.sciencemag.org.
The American Association for the Advancement of Science,
”Triple A-S” (AAAS), is an international non-profit organization dedicated to advancing science around the world by serving as an educator, leader, spokesperson and professional association. In addition to organizing membership activities, AAAS publishes the journal Science, as well as many scientific newsletters, books and reports, and spearheads programs that raise the bar of understanding for science worldwide.
Harry M. Quiney, Paolo Barletta, György Tarczay, Attila G. Császár, Oleg L. Polyansky, Jonathan Tennyson,
Two-electron relativistic corrections to the potential energy surface and vibration-rotation levels of water,
Chemical Physics Letters, 2001, Volume 344, Pages 413-420,
DOI: 10.1016/S0009-2614(01)00784-9.
Annotation
Two-electron relativistic corrections to the ground-state electronic energy of water are determined as a function of geometry at over 300 points. The corrections include the two-electron Darwin term (D2) of the Coulomb–Pauli Hamiltonian, obtained at the cc-pVQZ CCSD(T) level of theory, as well as the Gaunt and Breit corrections, calculated perturbationally using four-component fully variational Dirac–Hartree–Fock (DHF) wavefunctions and two different basis sets. Based on the calculated energy points, fitted relativistic correction surfaces are constructed. These surfaces are used with a high-accuracy ab initio nonrelativistic Born–Oppenheimer (BO) potential energy hypersurface to calculate vibrational band origins and rotational term values for H2(16)O. The calculations suggest that these two-electron relativistic corrections, which go beyond the usual kinetic relativistic effects and which have so far been neglected in rovibrational calculations on light many-electron molecular systems, have a substantial influence on the rotation–vibration levels of water. The three effects considered have markedly different characteristics for the stretching and bending levels, which often leads to fortuitous cancellation of errors. The effect of the Breit interaction on the rovibrational levels is intermediate between the effect of the kinetic relativistic correction and that of the one-electron Lamb-shift effect.
Chemical Physics Letters publishes brief reports of original research on the structures, properties and dynamics of molecules, solid surfaces, interfaces, condensed phases, polymers, nanostructures and biomolecular systems.
Criteria for publication are quality, urgency and impact. Further, experimental results reported in the journal have direct relevance for theory, and theoretical developments or non-routine computations relate directly to experiment.
Manuscripts must satisfy these criteria and should not be minor extensions of previous work or just descriptions of the synthesis of molecules or materials.
As the world’s leading publisher of science and health information, Elsevier serves more than 30 million scientists, students, and health and information professionals worldwide.
We are proud to play an essential role in the global science and health communities and to contribute to the advancement of these critical fields. By delivering world-class information and innovative tools to researchers, students, educators and practitioners worldwide, we help them increase their productivity and effectiveness. We continuously make substantial investments that serve the needs of the global science and health communities.
Tennyson J., N.F. Zobov, R. Williamson, O.L. Polyansky and P.F. Bernath,
Experimental Energy Levels of the Water Molecule,
Journal of Physical and Chemical Reference Data, 2001, Volume 30, Issue 3, Pages 735-831,
DOI: 10.1063/1.1364517, http://link.aip.org/link/?JPCRBU/30/735/1.
Annotation
Experimentally derived energy levels are presented for 12248 vibration–rotation states of the H2(16)O isotopomer of water, more than doubling the number in previous, disparate, compilations. For each level an error and reference to source data is given. The levels have been checked using energy levels derived from sophisticated variational calculations. These levels span 107 vibrational states including members of all polyads up to and including 8nu. Band origins, in some cases estimates, are presented for 101 vibrational modes.
Journal
Journal of Physical and Chemical Reference Data [J. Phys. Chem. Ref. Data], American Institute of Physics,
ISSN: 0047-2689, http://ojps.aip.org/jpcrd/.
Focus and Coverage
Journal of Physical and Chemical Reference Data is published by the American Institute of Physics (AIP) for the National Institute of Standards and Technology (NIST); content is published online daily, collected into quarterly online and printed issues (4 issues per year). The objective of the Journal is to provide critically evaluated physical and chemical property data, fully documented as to the original sources and the criteria used for evaluation, preferably with uncertainty analysis. Critical reviews of measurement techniques may also be included if they shed light on the accuracy of available data in a technical area. Papers reporting correlations of data or estimation methods are acceptable only if they are based on critical data evaluation and if they produce “reference data”—the best available values for the relevant properties. The journal is not intended as a publication outlet for original experimental measurements such as those normally reported in the primary research literature, nor for review articles of a descriptive or primarily theoretical nature.
One source of contributions to the Journal is The National Standard Reference Data System (NSRDS), which was established in 1963 as a means of coordinating on a national scale the production and dissemination of critically evaluated reference data in the physical sciences. Under the Standard Reference Data Act (Public Law 90-396) the National Institute of Standards and Technology of the U.S. Department of Commerce has the primary responsibility in the Federal Government for providing reliable scientific and technical reference data. The Standard Reference Data Program of NIST coordinates a complex of data evaluation centers, located in university, industrial, and other Government laboratories as well as within NIST, which are engaged in the compilation and critical evaluation of numerical data on physical and chemical properties retrieved from the world scientific literature. The participants in this NIST-sponsored program, together with similar groups under private or other Government support which are pursuing the same ends, compose the National Standard Reference Data System.
The primary focus of the NSRDS is on well-defined physical and chemical properties of well-characterized materials or systems. An effort is made to assess the accuracy of data reported in the primary research literature and to prepare compilations of critically evaluated data which will serve as reliable and convenient reference sources for the scientific and technical community.
The American Institute of Physics (AIP) is a 501(c)(3) not-for-profit membership corporation created for the purpose of promoting the advancement and diffusion of the knowledge of physics and its application to human welfare. It is the mission of the Institute to serve the sciences of physics and astronomy by serving its member societies, by serving individual scientists, and by serving students and the general public.
Shirin S.V., O.L. Polyansky, N.F. Zobov, P. Barletta and J. Tennyson,
Spectroscopically determined potential energy surface of H216O up to 25 000 cm-1,
Journal of Chemical Physics, 2003, Volume 118, Issue 5, Pages 2124-2129,
DOI: 10.1063/1.1532001.
Annotation
A potential energy surface for the major isotopomer of water is constructed by fitting to observed vibration–rotation energy levels of the system using the exact kinetic energy operator nuclear motion program DVR3D. The starting point for the fit is the ab initio Born-Oppenheimer surface of Partridge and Schwenke [J. Chem. Phys. 106, 4618 (1997)] and corrections to it: both one- and two-electron relativistic effects, a correction to the height of the barrier to linearity, allowance for the Lamb shift and the inclusion of both adiabatic and nonadiabatic non-Born–Oppenheimer corrections. Fits are made by scaling the starting potential by a morphing function, the parameters of which are optimized. Two fitted potentials are presented which only differ significantly in their treatment of rotational nonadiabatic effects. Energy levels up to 25 468 cm-1 with J = 0, 2, and 5 are fitted with only 20 parameters. The resulting potentials predict experimentally known levels with J<10 with a standard deviation of 0.1 cm–1, and are only slightly worse for J = 20, for which rotational nonadiabatic effects are significant. The fits showed that around 100 known energy levels are probably the result of misassignments. Analysis of misassigned levels above 20 000 cm–1 leads to the reassignment of 23 transitions.
Journal
The Journal of Chemical Physics [J. Chem. Phys.], American Institute of Physics,
ISSN: 0021-9606, http://ojps.aip.org/jcpo/.
The purpose of The Journal of Chemical Physics is to bridge a gap between journals of physics and journals of chemistry by publishing quantitative research based on physical principles and techniques, as applied to "chemical" systems. Just as the fields of chemistry and physics have expanded, so have chemical physics subject areas, which include polymers, materials, surfaces/interfaces, and biological macromolecules, along with the traditional small molecule and condensed phase systems. The Journal of Chemical Physics (JCP) is published four times per month (48 issues per year) by the American Institute of Physics.
The American Institute of Physics (AIP) is a 501(c)(3) not-for-profit membership corporation created for the purpose of promoting the advancement and diffusion of the knowledge of physics and its application to human welfare. It is the mission of the Institute to serve the sciences of physics and astronomy by serving its member societies, by serving individual scientists, and by serving students and the general public.
Polyansky O.L., A. G. Császár, S.V. Shirin, N.F. Zobov, P. Barletta, J. Tennyson, D.W. Schwenke and P.J. Knowles,
High-Accuracy ab Initio Rotation-Vibration Transitions for Water,
Science, 2003, Volume 299, no. 5606, Pages 539-542,
DOI: 10.1126/science.1079558.
Annotation
The spectrum of water vapor is of fundamental importance for a variety of processes, including the absorption and retention of sunlight in Earth's atmosphere. Therefore, there has long been an urgent need for a robust and accurate predictive model for this spectrum. In our work on the high-resolution spectrum of water, we report first-principles calculations that approach experimental accuracy. To achieve this, we performed exceptionally large electronic structure calculations and considered a variety of effects, including quantum electrodynamics, which have routinely been neglected in studies of small many-electron molecules. The high accuracy of the resulting ab initio procedure is demonstrated for the main isotopomers of water.
Journal
Science [Science], The American Association for the Advancement of Science, www.sciencemag.org.
The American Association for the Advancement of Science,
”Triple A-S” (AAAS), is an international non-profit organization dedicated to advancing science around the world by serving as an educator, leader, spokesperson and professional association. In addition to organizing membership activities, AAAS publishes the journal Science, as well as many scientific newsletters, books and reports, and spearheads programs that raise the bar of understanding for science worldwide.
Callegari A., P. Theule, R.N. Tolchenov, N.F. Zobov, O.L. Polyansky, J. Tennyson, J.S. Muenter and T.R. Rizzo,
Dipole moments of highly vibrationally excited water,
Science, 2002, Volume 297, Pages 993-995,
DOI: 10.1126/science.1073731.
Annotation
The intensity of water absorption in the region of the solar spectrum plays a dominant role in atmospheric energy balance and hence strongly influences climate. Significant controversy exists over how to model this absorption accurately. We report dipole moment measurements of highly vibrationally excited water, which provide stringent tests of intensities determined by other means. Our measurements and accompanying calculations suggest that the best currently available potential and dipole surfaces do not accurately model intensities in the optical spectrum of water.
Journal
Science [Science], The American Association for the Advancement of Science, www.sciencemag.org.
The American Association for the Advancement of Science,
”Triple A-S” (AAAS), is an international non-profit organization dedicated to advancing science around the world by serving as an educator, leader, spokesperson and professional association. In addition to organizing membership activities, AAAS publishes the journal Science, as well as many scientific newsletters, books and reports, and spearheads programs that raise the bar of understanding for science worldwide.
