L.R. Brown

NH3 and PH3 Line Parameters: The 2000 HITRAN Update and New Results

This paper describes the improvements incorporated into the 2000 version of the HITRAN database for ammonia (NH_3), as well as newer results for phosphine (PH_3) not included in HITRAN 2000. For ammonia, the HITRAN 2000 database contains some 29084 ammonia lines, more than double the number of lines in HITRAN 1996. Specifically, the 2000 update involved replacing pure-rotational and infrared transitions from 0 to 3700 cm^(-1) with new calculations for the ^(14)NH_3 isotopomer, whereas in the 4000 to 5000 cm^(-1) region, parameters from the 1996 database were retained. The rotational quantum number range for line positions, intensities and line broadening parameters updated in this new HITRAN version goes up to J=22, 15, 13 and 10 in the 8–1000 μm, 5 μm, 4 μm and 2.8–3.3 μm spectral regions respectively. For phosphine, a new database from 770 to 2156 cm^(-1) available for future updates is described and contrasted with parameters in HITRAN 2000.

Analysis of the ν2ν4 dyad of 12CH4 and 13CH4

Abstract The reanalysis of the ν 2 ν 4 dyad of 12CH4 and the first detailed analysis of the same dyad of 13CH4 have been carried out using new infrared measurements combined with previously published microwave data. The line positions of the ν 2 ν 4 dyad near 7 μm have been measured with a precision of 0.00006 cm−1 using 0.0055 and 0.011 cm−1 resolution spectra recorded with the Fourier Transform spectrometer at Kitt Peak National Observatory/National Solar Observatory. Using a sixth order reduced Hamiltonian, the ground state and the ν 2 ν 4 upper state parameters have been adjusted simultaneously. Standard deviations of 0.065 10−3 cm−1 involving data through J = 23 for 12CH4 and 0.062 10−3 cm−1 involving data through J = 19 for 13CH4 have been obtained. Over 7100 infrared transitions of methane (with strengths greater than 10−6 cm−2 atm−1 at 296 K in natural isotopic abundance) have been calculated. The majority of the predicted line positions have individual standard deviations of 10−4 cm−1 or better.

The vibrational ground state of 12CH4 and 13CH4

Abstract Improved ground state constants of 12 CH 4 and 13 CH 4 have been obtained using new infrared measurements combined with previously published microwave data. The line positions of the ν 2 ν 4 dyad near 7 μm have been measured with a precision of 0.00006 cm −1 using 0.0055 and 0.011 cm −1 resolution spectra recorded with the Fourier transform spectrometer at Kitt Peak National Observatory/National Solar Observatory. Using a sixth order Hamiltonian, the ground state and the ν 2 ν 4 upper states (J. P. Champion, J. C. Hilico, C. Wenger and L. R. Brown, J. Mol. Spectrosc. 133, 256–272 (1989)) have been fitted simultaneously to within the precision of the data through J = 23 for 12 CH 4 and J = 19 for 13 CH 4 . Absolute ground state energies and their standard deviations are given up to J = 30 for both isotopes. For Q - and R -branch transitions within the ground states, the statistical precisions from this study are similar (in the same order of magnitude) to the precision of microwave measurements.

The infrared spectrum of CH3D between 900 and 3200 cm−1: extended assignment and modeling

Abstract The high resolution infrared spectrum of CH 3 D in the region from 900 to 3200xa0cm −1 has been analyzed on the basis of Fourier transform spectra recorded at Kitt Peak and at Giessen. A theoretical model for an effective hamiltonian in terms of irreducible tensor operators recently adapted to symmetric top molecules has been used in order to consider simultaneously all available transitions between the lowest three polyads of the molecule: the Ground State (G.S.), the Triad (three interacting fundamental bands in the 8xa0μm region) and the Nonad (nine interacting bands in the 4xa0μm region). A preliminary simultaneous fit of 3467 Triad–G.S., 5208 Nonad–G.S., and 2487 Nonad–Triad (hot band) transition wavenumbers has been done. The standard deviations achieved were 2.1, 4.7 and 4.3×10 −3 xa0cm −1 , respectively. A preliminary analysis of the transition intensities was also undertaken at a level of precision of the order of 5% or better.

The vibrational and rotational spectra of ozone for the (0, 1, 0) and (0, 2, 0) states

Author Institution: Jet Propulsion Laboratory, California Institute of Technology; Atmospheric Sciences Division, NASA Langley Research Center; Department of Physics, College of William and Mary; Department of Physics, University of Denver; Laboratiore de Spectrom{e}trie Mol{e}culaire et Atmosph{e}rique, Unit{e} Associ{e}e au CNRS; Istituto di Ricerca sulle Onde Elettromagnetiche CNR-IROE, Firenze, Italy, Unit{e} Associ{e}e au CNRS; Istituto di Chimica Fisica e Spettroscopia, Universit`{a} di Bologna, Italy, Unit{e} Associ{e}e au CNRS

Linestrengths of the ν2 and ν4 bands of 12CH4 and 13CH4

Abstract The objectives of this study were to determine band strengths and obtain calculations that correctly predict individual linestrengths through five orders of magnitude of absorption strength and high values of J ′. For this, individual linestrengths of the two lowest fundamentals of methane in the 1080- to 1752-cm −1 region were measured from absorption spectra recorded on the high-resolution Fourier transform spectrometer at Kitt Peak National Observatory/National Solar Observatory. Transition strengths were modeled using the dyad formalism of two interacting bands and a seven term second-order dipole moment expansion. For 12 CH 4 , 760 lines of ν 4 through J = 23 and 446 lines of ν 2 through J = 19 were fitted to an rms of 3%. In addition, linestrengths of 13 CH 4 measured in normal isotopic abundance were modeled; 165 transitions of ν 4 through J = 15 and 35 lines of ν 2 through J = 14 were fitted with an rms of 4%. The complete prediction of the absorption arising from these bands up to J = 23 for 12 CH 4 and J = 19 for 13 CH 4 was done. The sum of linestrengths at 296 K for 100% abundance for the two bands combined is 130.4 cm −2 ·atm −1 for 12 CH 4 and 125.2 cm −2 ·atm −1 for 13 CH 4 . The absolute accuracies for the two isotopes are 3 and 4%, respectively.

Line strengths of the ν2 + ν3 and ν3 − ν2 bands of methane (12CH4)

Abstract The individual linestrengths of two related bands of 12 CH 4 , ν 2 + ν 3 near 4545 cm −1 and ν 3 − ν 2 near 1484 cm −1 , were measured with accuracies of 3% and 5%, respectively. In the analysis, an eight-term expansion of the dipole moment through second order was required to fit the strengths of transitions up to J ′ = 10 in ν 2 + ν 3 and J ′ = 12 in ν 3 − ν 2 and to explain the considerable perturbations observed. Application of this model reduced the rms deviations from 68% (zero-order) to 6.3% with the 248 selected lines of ν 2 + ν 2 and from 37% to 5.8% with 186 lines of ν 3 − ν 2 . The integrated bandstrengths for the two bands, respectively, are 1.84(5) and 0.0085(4) cm −2 ·atm −1 at 296 K for a 100% sample of 12 CH 4 . Predictions of both bands of 12 CH 4 and ν 2 + ν 3 of 13 CH 4 are available for lines with strengths greater than 10 −6 cm −2 ·atm −1 at 296 K.

THE ROVIBRATIONAL INTENSITIES OF THE 2ν3 BAND OF 12C16O18O AT 4639 cm-1

Abstract The absolute intensities of transitions in the 2 ν 3 vibrational band of 12 C 16 O 18 O at 4639.5xa0cm -1 have been measured in natural isotopic abundance; the spectra were obtained with 0.012xa0cm -1 resolution using the McMath Fourier transform spectrometer of the National Solar Observatory located at Kitt Peak National Observatory. About 70 transitions have been fitted with an rms deviation of approximately 1.5% to obtain the rotationless band strength of S 0 vib =1.442×10 -23 xa0cm molecule -1 at 296xa0K along with a small first-order Herman–Wallis parameter of A 1 =3.5×10 -5 ; higher order Herman–Wallis parameters could not be determined. The measured line positions, obtained using the CO 2 gas samples in the range of 45–65xa0Torr at room temperature, confirm the current HITRAN tabulated values. The internal precision of our intensity measurements is very high, and the uncertainty due to possible systematic errors is judged to be less than ±3%.