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 required for high-resolution radiative-transfer codes, infrared absorption cross-sections for molecules not yet amenable to representation in a line-by-line form, collision-induced absorption data, aerosol indices of refraction, and general tables such as partition sums that apply globally to the data. The new HITRAN is greatly extended in terms of accuracy, spectral coverage, additional absorption phenomena, added line-shape formalisms, and validity. Moreover, molecules, isotopologues, and perturbing gases have been added that address the issues of atmospheres beyond the Earth. Of considerable note, experimental IR cross-sections for almost 300 additional molecules important in different areas of atmospheric science have been added to the database. The compilation can be accessed through www.hitran.org. Most of the HITRAN data have now been cast into an underlying relational database structure that offers many advantages over the long-standing sequential text-based structure. The new structure empowers the user in many ways. It enables the incorporation of an extended set of fundamental parameters per transition, sophisticated line-shape formalisms, easy user-defined output formats, and very convenient searching, filtering, and plotting of data. A powerful application programming interface making use of structured query language (SQL) features for higher-level applications of HITRAN is also provided.

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The HITRAN 2008 molecular spectroscopic database

A semiclassical theory of the width and shift of isolated infrared and Raman lines in the gas phase is developed within the impact approximation. A parabolic trajectory model determined by the isotropic part of the interaction potential allows a satisfactory treatment to be made of the close collisions leading to an analytical expression for the elastic collision cross section. A numerical test of this theory has been made for HCl-Ar by comparing the present results to those of previous infinite order treatments using numerical curved classical trajectories. Extension to the diatom-diatom collisions is then made by expressing the anisotropic potential using an atom-atom interaction model which takes both the long and short range contributions into account. Numerical applications have been performed for the Raman line widths of pure N2, CO2 and CO and for the infrared line widths of pure CO and of CO perturbed by N2 and CO2. A good quantitative agreement with experiments is obtained for all the considered cases and a correct variation of the broadening coefficient with the rotational quantum number is achieved in opposition to the previous results. A consistent variation of the line broadening with temperature is also obtained even for high rotational levels.

https://hal.archives-ouvertes.fr/jpa-00209180/document

Short range force effects in semiclassical molecular line broadening calculations

Spectral and total emissivity of water vapor and carbon dioxide

Self-, N2-, O2-, H2-, Ar-, and He-broadening coefficients, pressure shifts, and integrated intensities have been measured for most transitions in the Q branch of the nu3 fundamental band of methane using a difference-frequency laser spectrometer. A systematic dependence of the broadening coefficients on the tetrahedral symmetry species and order index is observed with striking similarities for N2, O2, and Ar and for H2 and He buffer gases. Comparison with earlier measurements on other bands and branches of methane indicates very little vibrational, branch, or carbon isotope dependence. Dicke narrowing is evident at intermediate pressures, yielding an average narrowing coefficient and an optical diffusion constant for each gas mixture.

Self‐, N2, O2, H2, Ar, and He broadening in the ν3 band Q branch of CH4

Spectral intensities in the fundamental bands of HF and HCl

High-resolution experimental and theoretical studies performed earlier by us on the collision-broadened rotational lines in the nu-3 and 2nu-3 bands of methane have been repeated on the lines in the nu-4 fundamental of the molecule. Line-width measurements and computations, as well as line-shape measurements, indicate that the significant differences which exist between the rotational term values of the nu-3 and nu-4 vibrational levels have no observable effect on the collision-broadening mechanism. Using the predictions of line-widths, based on the Anderson-Tsao-Curnutte theory in the extended version of Tejwani for octopolar molecules, the theoretical dependence of line-widths on temperature has been calculated for CH4-CH4, CH4-H2 and CH4-He collisions.

Experimental and theoretical studies on collision-broadened lines in the v4-fundamental of methane

Results of high-resolution (0.1 cm/cm) on several CO2-broadened lines in the fundamentals of HCl35 and HCl37. Line intensities, half-widths, and shapes were determined at room temperature. Half-widths in HCl-CO2 collisions were computed for several temperatures, employing Anderson's (1949) theory. The measured shapes of HCl lines broadened by CO2 are described by a semiempirical super-Lorentzian shape. The curve-of-growth for this line shape is derived in terms of a function similar to the Ladenburgh-Reiche function. Absorption between R(0) and P(1) is affected by the appearance of several pressure-induced Q-branch lines, at the pressures from 1 to 10 atm used in the present study.

http://dspace.nitrkl.ac.in:8080/dspace/bitstream/2080/242/1/skso1.pdf

Line shape parameters for HCl and HF in a CO2 atmosphere

Pressure-broadened widths of CH4 lines have been calculated, using the recent formulation for tetrahedral molecules by Varanasi in the framework of the Anderson-Tsao-Curnutte theory. The present work deals mainly with lines of the R-branch of the ν3-fundamental at 300°K, for the range 1≤J≤30 and 0≤K≤18, and for the F species. In the case of CH4-N2 and CH4-O2 collisions, octopole-quadrupole, octopole-hexadecapole, hexadecapole-quadrupole, hexadecapole-hexadecapole, dispersion and overlap interactions have been included. Broadening by noble gases was treated in terms of dispersion and overlap interactions. The value |ΩCH4|=2·25×10−34 esu cm3 obtained in the present work by comparing theoretical and experimental results for γ0CH4−N2 is not far from the magnitude deduced in studies of the far-i.r. collision-induced absorption spectra of methane. A magnitude for the hexadecapole moment of |ΦCH4|=3·0×10−42 esu cm4 was also determined. The calculated and measured linewidths are in good agreement, except in CH4-Ar collisions. In the latter case, the theoretical values are appreciably lower than the experimental ones, which suggests that induced interactions may have to be included.

Collision-broadened linewidths of tetrahedral molecules—II. Computations for CH4 lines broadened by N2, O2, He, Ne and Ar

Half-widths of CO lines, in the fundamental and first overtone bands, broadened by CO 2 have been computed using the Anderson-Tsao-Curnutte theory. Comparison with the high-resolution measurements of Varanasi at 295°K shows excellent prediction of line widths by the theory. Comparison is also made between calculations including dipole-quadrupole and quadrupole-quadrupole interactions with those taking only the dominant quadrupole-quadrupole forces into account. Line widthd at 295°K range from 0.126417 cm -1 atm -1 fom m = 1 to 0.04397 cm -1 atm -1 for m = 32, which corresponds to the asymptonic kinetic-theory value. Half-width computations are also presented at 200°K and 250°K appropriate for Martian and Venusian atmospheres, respectively.

Half-width calculations for CO lines broadened by CO2

The theory of Anderson, Tsao and Curnutte has been applied to compute half widths of CO lines broadened by N2, O2 and air. The results are compared with available experimental data.

G.D.T. Tejwani

Papers

Experimental and theoretical studies on collision-broadened lines in the v4-fundamental of methane

Line shape parameters for HCl and HF in a CO2 atmosphere

Collision-broadened linewidths of tetrahedral molecules—II. Computations for CH4 lines broadened by N2, O2, He, Ne and Ar

Half-width calculations for CO lines broadened by CO2

Half-width computations for air broadened CO lines