Sergey Tashkun

• PhD
• Researcher at V.E. Zuev Institute of Atmospheric Optics

In this work, we provide the most complete to date reference data for 28 572 rovibrational levels of the electronic ground state of the ozone ¹⁶O3 molecule up to the maximum rotational quantum numbers J = 80, Ka = 29 determined from 75 290 experimental transitions covering the range (0.3–7999) cm⁻¹. These energy levels belong to 98 vibrational stat...

To facilitate atmospheric and spectroscopic studies of carbon disulfide, or CS 2 , in both planetary and exoplanetary atmospheres, we adopt the “Best Theory + Reliable High-resolution Experiment” algorithm to generate semiempirical IR line lists for the 20 most abundant CS 2 isotopologues, denoted as Ames-296K. The IR lists are computed using the A...

The paper describes methods and fast computational algorithm for building effective Hamiltonians in molecular physics using perturbative approach. Separations of fast and slow variables are considered in the framework of contact transformations (CT). The particular focus is on a systematic derivation of effective models for rovibrational spectrosco...

The weak high-resolution absorption spectrum of natural nitrous oxide has been recorded by high sensitivity cavity ring down spectroscopy (CRDS) near 1.18 µm. The frequency scale of the spectra was obtained by coupling the CRDS spectrometer to a self-referenced frequency comb. The room temperature recordings, performed with a pressure of 1 Torr, co...

This paper presents an overview of the current status of the Virtual Atomic and Molecular Data Centre (VAMDC) e-infrastructure, including the current status of the VAMDC-connected (or to be connected) databases, updates on the latest technological development within the infrastructure and a presentation of some application tools that make use of th...

Four spectra of normal samples of CH4 in the 4300-4600 cm⁻¹ region were recorded by using a Fourier transform spectrometer in Reims, France at long paths (202 m, 602 m, 1604 m, and 1804 m) and different pressures. Additional spectra of ¹²CH4 covering the same region were obtained at 80-123 K, and 93 m path length at SOLEIL Synchrotron in Paris for...

The room temperature absorption spectrum of ¹⁷O enriched carbon dioxide is investigated by high sensitivity cavity ring down spectroscopy (CRDS) between 5695 and 5850 cm⁻¹. About 1100 lines are measured and assigned to 26 bands of the six ¹⁷O containing carbon dioxide isotopologues: ¹⁶O¹²C¹⁷O, ¹⁶O¹³C¹⁷O, ¹⁷O¹²C¹⁸O, ¹⁷O¹³C¹⁸O, ¹²C¹⁷O2 and ¹³C¹⁷O2. T...

This work describes the update of NO along with the incorporation of NO$_{2}$ and N$_{2}$O to the HITEMP database. Where appropriate, the HITRAN line lists for the same molecules have also been updated. This work brings the current number of molecules provided by HITEMP to seven. The initial line lists originating from \textit{ab initio} and semi-e...

The global modeling of ¹⁴ N 2¹⁶ O line positions in the 0.8–14,917 cm ⁻¹ region has been performed using the non-polyad model of effective Hamiltonian. The effective Hamiltonian parameters were fitted to the measured line positions collected from the literature. The dimensionless weighted standard deviation of the fit is 1.71. The fitted set of 195...

This work describes the update of NO along with the incorporation of NO 2 and N 2 O to the HITEMP database. Where appropriate, the HITRAN line lists for the same molecules have also been updated. This work brings the current number of molecules provided by HITEMP to seven. The initial line lists originating from ab initio and semi-empirical methods...

The Fourier transform spectrum of CF4 in the 1600–1800 cm−1 was recorded in Reims by using a White-type multi-pass cell to provide a path length of 8.262 m. In the present work, all spectrum analyses and fits were realized using the MIRS software based on tetrahedral tensorial formalism. By combining non-empirical contact transformation Hamiltonian...

In 2015 we published an atmospheric version, CDSD-296, of the carbon dioxide spectroscopic databank (CDSD) [Tashkun et al., JQSRT 152 (2015) 45–73]. Since that time many new experimental data have been published. Some CDSD data deficiencies have also been found. The purpose of the present work is to present a corrected and extended version of the d...

Eight spectra of normal samples of CH4 in the 3760–4100 cm⁻¹ region were recorded by using a Fourier transform spectrometer in Reims, France at long paths (202 m, 602 m, 1604 m and 1804 m) and different pressures. Additional spectra of ¹²CH4 covering the same region were obtained at 100 K and very low sample pressures, which was used for low-J line...

A new study of ¹²CH4 line positions and intensities was performed for the Tetradecad regions 5550,000–5695.250, 5718.8–5724.250 and 5792.36–5814.290 cm⁻¹ using long path (202 m, 602 m, 1604 m and 1804 m) spectra of normal samples of CH4 at different pressures recorded with a Fourier transform spectrometer in Reims, France. Line positions and intens...

The very weak absorption spectrum of the minor isotopologues of carbon dioxide near 1.74 µm (5702–5879 cm⁻¹) is studied by high sensitivity cavity ring down spectroscopy (CRDS) with an ¹⁸O enriched sample. The investigated spectral region corresponds to a transparency window of very weak opacity which is of particular interest for Venus. Very weak...

This paper describes the contents of the 2016 edition of the HITRAN molecular spectroscopic compilation. The new edition replaces the previous HITRAN edition of 2012 and its updates during the intervening years. The HITRAN molecular absorption compilation is composed of five major components: the traditional line-by-line spectroscopic parameters re...

A new study of ¹²CH4 line positions and intensities was performed for part of the Tetradecad region between 5300 and 5550 cm⁻¹ using four long path (202 m, 602 m, 1604 m and 1804 m) spectra of normal samples of CH4 at different pressures recorded with a Fourier transform spectrometer in Reims, France. Line positions and intensities were retrieved b...

Accurate rovibrational analysis of the upper part of the Tetradecad ¹²CH4 spectrum in the 5855-6250 cm⁻¹ region is reported for J ≤ 10. The analysis uses the WKLMC experimental line list previously obtained in Grenoble by Cavity Ring Down Spectroscopy and Differential laser Absorption Spectroscopy at T= 296 K. Based on a previously published ab ini...

Total internal partition sums (TIPS) are reported for 166 isotopologues of 51 molecules important in planetary atmospheres. Molecules 1 to 50 are taken from the HITRAN2016 list, and, in some cases, additional isotopologues are considered for some of the molecules. Molecules 51-53 are C3H4, CH3, and CS2, respectively. TIPS are not reported for the O...

The absorption spectra of carbon dioxide have been recorded in the near infrared region from 10,000 to 10,300cm⁻¹, using the Bruker IFS 125HR Fourier transform spectrometer and a 30m multipass cell with the White type optical system. The spectra were recorded at a spectral resolution of 0.03cm⁻¹, room temperature, a path length of 953.6m and at two...

Improved analysis of positions and intensities of phosphine spectral lines in the Octad region 2733-3660 cm⁻¹ is reported. Some 5768 positions and 1752 intensities were modelled with RMS deviations of 0.00185 cm⁻¹ and 10.9%, respectively. Based on an ab initio potential energy surface, the full Hamiltonian of phosphine nuclear motion was reduced to...

The very weak absorption continuum of CO2 is studied by Cavity Ring Down Spectroscopy in three 20 cm⁻¹ wide spectral intervals near the centre of the 1.74 µm window (5693–5795 cm⁻¹). For each spectral interval, a set of room temperature spectra is recorded at pressures between 0 and 10 bar thanks to a high pressure CRDS spectrometer. The absorption...

Ab initio dipole moment surfaces (DMSs) of the ozone molecule are computed using the MRCI-SD method with AVQZ, AV5Z, and VQZ-F12 basis sets on a dense grid of about 1950 geometrical configurations. The analytical DMS representation used for the fit of ab initio points provides better behavior for large nuclear displacements than that of previous st...

In the present paper we report room temperature line lists for six asymmetric isotopologues of carbon dioxide: ¹⁶O¹²C¹⁸O (628), ¹⁶O¹²C¹⁷O (627), ¹⁶O¹³C¹⁸O (638),¹⁶O¹³C¹⁷O (637), ¹⁷O¹²C¹⁸O (728) and ¹⁷O¹³C¹⁸O (738), covering the range 0-8000cm⁻¹ . Variational rotation-vibration wavefunctions and energy levels are computed using the DVR3D software su...

This contribution is the second part of the analysis of the room temperature absorption spectrum of ¹⁸O enriched carbon dioxide by very high sensitivity Cavity Ring Down spectroscopy between 6977 and 7918 cm⁻¹ (1.43–1.26 μm). Overall, more than 8600 lines belonging to 166 bands of eleven carbon dioxide isotopologues were rovibrationnally assigned....

In the present paper we report room temperature line lists for six asymmetric isotopologues of carbon dioxide: 16O12C18O (628),16O12C17O (627),16O13C18O (638),16O13C17O (637),17O12C18O (728) and 17O13C18O (738), covering the range 0-8000 cm^-1. Variational rotation-vibration wavefunctions and energy levels are computed using the DVR3D software suit...

The room temperature absorption spectrum of ¹⁸O enriched carbon dioxide has been recorded by very high-sensitivity Cavity Ring Down spectroscopy between 6977 and 7918 cm⁻¹ (1.43−1.26 μm). The achieved sensitivity (noise equivalent absorption αmin ~8×10⁻¹¹ cm⁻¹) has allowed for the detection of more than 8600 lines belonging to 166 bands of eleven c...

The absorption of carbon dioxide is very weak near 2.3 µm which makes this transparency window of particular interest for the study of Venus’ lower atmosphere. As a consequence of the weakness of the transitions located in this region, previous experimental data are very scarce and spectroscopic databases provide calculated line lists which should...

The GEISA database (Gestion et Etude des Informations Spectroscopiques Atmosphériques: Management and Study of Atmospheric Spectroscopic Information) has been developed and maintained by the ARA/ABC(t) group at LMD since 1974. GEISA is constantly evolving, taking into account the best available spectroscopic data. This paper presents the 2015 relea...

The Virtual Atomic and Molecular Data Centre (VAMDC) Consortium is a worldwide consortium which federates atomic and molecular databases through an e-science infrastructure and an organisation to support this activity. About 90% of the inter-connected databases handle data that are used for the interpretation of astronomical spectra and for modelli...

The global modeling of 15N216O line positions in the 4–12516 cm−1 region has been performed using the polyad model of effective Hamiltonian. The effective Hamiltonian parameters were fitted to the line positions collected from an exhaustive review of the literature. The dimensionless weighted standard deviation of the fit is 1.31. The fitted set of...

In a recent work (Karlovets et al., 2016 [1]), we reported the measurement and rovibrational assignments of more than 3300 transitions belonging to 64 bands of five nitrous oxide isotopologues (14N216O, 14N15N16O, 15N14N16O, 14N218O and 14N217O) in the high sensitivity CRDS spectrum recorded in the 7915-8334 cm-1 spectral range. The assignments wer...

The absorption spectrum of the 13CH4 methane isotopologue has been recently recorded by Differential Absorption Spectroscopy (DAS) at 80 K in the 5853–6201 cm−1 spectral range. An empirical list of 3717 lines was constructed for this spectral range corresponding to the upper part of the Tetradecad dominated by the 2ν3 band near 5987 cm−1. In this w...

A new study of 13CH4 line intensities and positions was performed in the Octad region between 3750 and 4700 cm−1. Using 13C-enriched samples, spectra were recorded with both the McMath-Pierce FTS at Kitt Peak Observatory in Arizona and the Bruker IFS-125HR at JPL. Sample temperatures ranged between 80 and 296 K. Line positions and intensities of ~1...

Atmospheric carbon dioxide concentrations are being closely monitored by remote sensing experiments which rely on knowing line intensities with an uncertainty of 0.5% or better. We report a theoretical study providing rotation-vibration line intensities substantially within the required accuracy based on the use of a highly accurate ab initio dipol...

The temperature dependence of the methane 12CH4 partition function was investigated up to T=3000K. The ro-vibrational energy levels were calculated using high-order contact transformation (CT) method that permitted building accurate effective Hamiltonian models for highly excited vibration-rotation states from the molecular potential energy surface...

The absorption spectrum of the 16O12C18O and 12C18O2 carbon dioxide isotopologues has been recorded in the 11,260- 11,430cm-1 spectral range using Bruker IFS 125 HR Fourier transform spectrometer with resolution 0.05cm-1 at temperature 297K and path length 24m. The 18O enriched sample of carbon dioxide at total pressure 96.5mbar was used for these...

Three bands 4003i-00001 (i=2, 3, 4) of the Fermi pentad of 12C16O2 near 830nm have been recorded with a continuous-wave cavity ring down spectrometer. A sensitivity at the 5×10-11cm-1 level allowed us to obtain line positions and intensities of these very weak bands. The measured line intensities of these three bands together with those published f...

We present a high-temperature version, NOSD-1000, of the nitrous oxide spectroscopic databank. The databank contains the line parameters (positions, intensities, air- and self-broadened half-widths and coefficients of temperature dependence of air- and self-broadened half-widths) of the most abundant isotopologue 14N216O of the nitrous oxide molecu...

The absorption spectra of carbon dioxide have been recorded in two wavenumber ranges 9250–9500 cm−1 and 10,700–10,860 cm−1 of the near infrared region using a Bruker IFS 125 HR Fourier transform spectrometer and a 30 m multipass cell with the White type optical system. The spectra were recorded at spectral resolution of 0.03 cm−1, room temperature,...

The absorption spectrum of nitrous oxide (N2O) in natural isotopic abundance has been recorded near 1.22μm by Cavity Ring Down Spectroscopy using an External Cavity Diode Laser (ECDL) as light source. The room temperature recordings were performed at a pressure of 10.0Torr in the 7915-8334cm-1 spectral range (1.26-1.19μm). The typical noise equival...

Accurate rovibrational analysis of the lower part of the Icosad 12CH4 spectrum in the 6539-6800cm-1 region is reported. The analysis uses the WKLMC experimental line list previously obtained in Grenoble by Cavity Ring Down Spectroscopy and Differential Absorption Spectroscopy at T=80K. Based on an ab initio potential energy surface, the full Hamilt...

In Supplementary Material I of our paper the observed line intensities are given for the abundances of the carbon dioxide isotopologues in our sample but not for 100% abundance as it is written in the header of Supplementary Material I. The respective abundances are presented in the table below . Table. Abundances of CO2 isotopologues. Isotopologu...

The spectroscopic banks CDSD-296, CDSD-1000, and CDSD-4000 are presented in the context of integration into the Virtual Atomic and Molecular Data Centre (VAMDC) in order to extend the range of their users. A brief review of the VAMDC system is given concerning the purpose of this project, its infrastructure, and the data representation format. The...

Since the discovery of anomalies in ozone isotope enrichment, several fundamental issues in the dynamics linked to the shape of the potential energy surface in the transition state region have been raised. The role of the reeflike structure on the minimum energy path is an intricate question previously discussed in the context of chemical experimen...

A new study of 12CH4 line positions and intensities was performed for the lower portion of the Tetradecad region between 4800 and 5300 cm−1 using long path (1603 m) spectra of normal sample CH4 at three pressures recorded with the Fourier transform spectrometer in Reims, France. Line positions and intensities were retrieved by least square curve-fi...

We report the first intensity measurements for the very weak 20052-00001 band of the 2ν1 + 5ν3 triad of 13C16O2 near 734 nm by high sensitivity Intracavity Laser Absorption Spectroscopy. A noise equivalent absorption αmin ∼ 2 × 10−10 cm−1 was achieved with an absorption pathlength equivalent to 50.3 km. The derived intensity values (on the order of...

More than 19000 transitions belonging to 11 isotopologues of carbon dioxide have been assigned in the room temperature absorption spectrum of highly 18O enriched carbon dioxide recorded by very high sensitivity CW-Cavity Ring Down spectroscopy between 5851 and 6990 cm−1 (1.71–1.43 μm). The line positions were determined with accuracy better than 1×...

The room temperature absorption spectrum of highly 18O enriched carbon dioxide has been recorded by very high sensitivity CW-Cavity Ring Down spectroscopy between 5851 and 6990 cm−1 (1.71-1.43 μm). The achieved sensitivity (noise equivalent absorption αmin∼5×10−10−5×10-11 cm−1) has allowed the detection of more than 19,000 transitions belonging to...

The state of the art analyses of high-resolution ozone spectra and a critical discussion of line parameters updated since the previous review by Rinsland et al. [J Quant Spectrosc Radiat Transfer 2003;82:207–18] are presented. We focus on recent works revisiting improved measurements and analyses of Fourier transform spectra below 5600 cm‑1 and rev...

A new spectroscopic model is developed for theoretical predictions of vibration-rotation line positions and line intensities of the methane molecule. Resonance coupling parameters of the effective polyad Hamiltionians were obtained via high-order contact transformations (CT) from ab initio potential energy surface. This allows converging vibrationa...

An accurate description of the complicated shape of the potential energy surface (PES) and that of the highly excited vibration states is of crucial importance for various unsolved issues in the spectroscopy and dynamics of ozone and remains a challenge for the theory. In this work a new analytical representation is proposed for the PES of the grou...

Absorption spectra of carbon dioxide, 12C16O2, have been studied in the three wavenumber ranges (8790–8860, 9340–9650 and 11,430–11,505 cm−1) of the near infrared region using spectrophotometric complex of V.E. Zuev Institute of Atmospheric Optics based on an Bruker IFS 125 HR and a 30 m multipass cell with the White type optical system. The spectr...

The room temperature absorption spectra of nitrous oxide, N2O, have been recorded in the 6950–7653 cm−1 spectral region at 2 and 10 Torr using a CW-CRDS spectrometer based on 24 fibered DFB lasers. The achieved sensitivity (noise equivalent absorption αmin≈5×10–11 cm−1) allowed detecting lines with intensities as low as 1×10–29 cm/molecule. In the...

The dyad bands of 17O and 18O enriched carbon dioxide near 795 nm have been recorded with a continuous-wave cavity ring-down spectrometer. Seven cold bands of four isotopologues: 12C18O2, 16O12C18O, 16O12C17O and 12C17O2 have been observed for the first time. The spectroscopic parameters Gν, Bν, and centrifugal distortion constants, have been deter...

More than 19,700 transitions belonging to 11 isotopologues of carbon dioxide have been assigned in the room temperature absorption spectrum of highly 18O enriched carbon dioxide recorded by very high sensitivity CW-Cavity Ring Down spectroscopy between 5851 and 6990 cm−1 (1.71–1.43 μm). This third and last report is devoted to the analysis of the b...

The absorption spectrum of 13C16O2 near 806 nm has been recorded with a continuous-wave cavity ring-down spectrometer. Two cold bands and one associated hot band are observed in this region. The line positions of these bands are determined with an accuracy of 0.003 cm−1. The absolute line intensities have also been retrieved with an estimated accur...

The global modeling of 14N216O line positions in the 0–9700 cm−1 region has been performed using the polyad model of effective Hamiltonian. The effective Hamiltonian parameters were fitted to the line positions collected from an exhaustive review of the literature. A number of lines perturbed by interpolyad resonance interactions were excluded from...

The infrared spectrum of 16O3 has been revisited in the ranges 3300-3600 cm−1 and 5200-5600 cm−1, recorded by the Fourier Transform Spectrometer of Reims, with an improved signal/noise ratio. In the lower spectral range the weak 2ν1+2ν2 band is observed and assigned for the first time. This allowed for completing the triad of strongly interacting (...

Recently we have successfully applied the "Best Theory + High-resolution Experimental Data" strategy to NH{_3} and CO{_2}. The essential strategy is to refine a high quality, purely ab initio potential energy surface (PES) with reliable high resolution experimental data, so the IR line lists computed on the refined PES and dipole moment surface (DM...

Two independent methods to obtain ab initio effective rotational Hamiltonians have been implemented recently. The first one is based on a generalization of perturbation theory to noncommutative rings, the other one on contact transformation (CT) techniques. In principle, both methods are able to give rotational Hamiltonians including centrifugal di...

An isotopic-independent, highly accurate potential energy surface (PES) has been determined for CO(2) by refining a purely ab initio PES with selected, purely experimentally determined rovibrational energy levels. The purely ab initio PES is denoted Ames-0, while the refined PES is denoted Ames-1. Detailed tests are performed to demonstrate the spe...

High-resolution rovibrational spectroscopy of 15N216O in 1650–3450 cm−1 region is studied using highly enriched isotopologue sample. The positions of more than 7300 lines of 15N216O isotopologue were measured with a typical accuracy of 5.0×10−4 cm−1. The transitions were rovibrationally assigned on the basis of the global effective Hamiltonian mode...

The updated 2009 edition of the spectroscopic database GEISA (Gestion et Etude des Informations Spectroscopiques Atmosphériques; Management and Study of Atmospheric Spectroscopic Information) is described in this paper. GEISA is a computer-accessible system comprising three independent sub-databases devoted, respectively, to: line parameters, infra...

We present a high-resolution, high-temperature version of the Carbon Dioxide Spectroscopic Databank called CDSD-4000. The databank contains the line parameters (positions, intensities, air- and self-broadened half-widths, coefficients of temperature dependence of air- and self-broadened half-widths, and air-broadened pressure shifts) of the four mo...

Following the "Best Theory + High-resolution Experimental Data" strategy, we have completed an initial CO{_2} infrared (IR) line list, denoted Ames-1. A procedure similar to the one used for ammonia is adopted to generate a global potential energy surface (PES), including various small corrections such as scalar relativity, extrapolation to the one...

The absorption spectrum of nitrous oxide, N2O, in normal isotopic abundance has been recorded by CW-Cavity Ring Down Spectroscopy between 7647 and 7918cm−1. The spectra were obtained at Doppler limited resolution by using a CW-CRDS spectrometer based on a series of fibered DFB lasers. The typical noise equivalent absorption on the order of αmin≈1×1...

The absorption spectrum of nitrous oxide (N2O) has been recorded by Intracavity Laser Absorption Spectroscopy between 12,760 and 12,900 cm−1. The rotational analysis led to an improved determination of rovibrational parameters of the 6ν3 and 6ν3+ν2–ν2 bands of 14N216O. The high J rotational levels of the (0 0 06) and (0 1 16) upper states were foun...