S.N. Mikhailenko

Spectroscopic parameters for ozone and its isotopes: recent measurements, outstanding issues, and prospects for improvements to HITRAN

In this article we review ozone spectroscopy from the microwave to the ultraviolet since the release of the 1996 HITRAN database. Uncertainties, deficiencies, areas of potential improvement, and anticipated new spectral line parameters datasets are highlighted.

Analysis of high resolution measurements of the 2ν1 + 3ν3 band of ozone: Coriolis interaction with the ν1 + 3ν2 + 2ν3 band

Abstract The 2ν1 + 3ν3 band of ozone, which occurs in the 5080 cm−1 region, has been observed for the first time using a Fourier transform spectrometer, operating at 0.008 cm−1 resolution and with a large pathlength x pressure product (3616 cm × 42.8 torr). Assignment of rotation-vibration transitions was done for J = 40 and Ka = 14. It was necessary to account for the Coriolis coupling between the levels of the (203) and (132) states to correctly reproduce the energy levels, particularly for states with Ka = 4. In this way, we have obtained a very satisfactory r.m.s. error of 1.8 × 10−3 cm−1, close to the experimental accuracy. In addition, line intensities of the 2ν1 + 3ν3 band were measured and calculated, and transition moment constants derived. Finally a complete list of line positions and intensities was calculated, leading to a total band intensity of Sv = 0.133 × 10−21 cm−1/mole cm−2 at 296 K.

The 2ν2 and 3ν2−ν2 bands of ozone

Abstract The infrared spectra of 16O3 in the range 1300–1500 cm−1 have been recorded at high resolution (0.007 cm−1), with a large product p×l=32.4 Torr×3212 cm, and a good S/N ratio ≅500. This enables us to observe the 2ν2 band with high values of rotational quantum numbers, respectively J≤57 and Ka≤16, and also to observe for the first time the hot band 3ν2−ν2. The infrared data, combined with the 24 known microwave transitions in the (020) state, lead to a new set of Hamiltonian parameters. Statistical aspects of the simultaneous fit of microwave and infrared data are discussed and predictions of microwave transitions in the (020) state are given. The Hamiltonian parameters for (030) are reported, leading to an observation of a quasi linear dependence of rotational constants and the centrifugal distortion constant ΔK with respect to the v2 quantum number. Transition moment parameters are given for the 2ν2 and 3ν2−ν2 bands. A complete final calculation of line positions and intensities up to J≤65 and Ka≤20 leads to the integrated band intensity Sv (2ν2)=(5.328×10−22 cm−1)/(cm−2 molecule−1) at 296 K, with a cut-off of 2×10−26.

Infrared high-resolution spectra of ozone in the range 5500-: analysis of and bands

The and bands of ozone, which occur in the region, have been observed for the first time using a Fourier transform spectrometer, operating at resolution and with a large pathlength pressure product . The assignment of rotation-vibration transitions has been done for J up to 35 and Ka up to 12, for the band and up to J = 40 and Ka = 2 for the band respectively. The effective Hamiltonian used in calculations accounts for the first-order Coriolis coupling between these two bands. In addition, as the levels corresponding to Ka = 5 are perturbed, it was necessary to account for anharmonic resonance with the (321) state. Also, to correctly reproduce the levels of (015) with Ka = 8,9,10 it has been necessary to include a Coriolis coupling with (080) state in the model. In this way, we have obtained a very satisfactory r.m.s. deviation of , near the experimental accuracy. Rovibrational line intensities of and bands were measured and the value of the principal transition moment constants have been recovered. Finally a complete list of line positions and intensities was calculated leading to the integrated band intensity of /molecule for the band and /molecule for the band at 296 K with a cut-off of .

Update of line parameters of ozone in the 2550-2900 cm-1 region

An update of spectroscopic line parameters for the 3.45-3.92 microm ozone bands is reported. The line list includes the parameters of 15 bands of the main isotopic species and of the v1+v2+v3 band of 16O16O18O and 16O18O16O. The results are based on previous high resolution laboratory studies. Comparisons of experimental spectra with an absorptance simulation of ozone based on the reported line list shows that the latter one is accurate enough for strong, medium, and weak transmittance in the 2550-2900 cm(-1) spectral range. The data are available on the Web in the Spectroscopy and Molecular Properties of Ozone (S&MPO, http://smpo.iao.ru and http://ozone.univ-reims.fr) and HITRAN (http://cfa-www.harvard.edu/hitran/) databanks.

The absorption spectrum of H218O in the range 13400–14460 cm−1

Using a Fourier-transform spectrometer, we have measured the absorption spectrum of H218O vapor in the range 13400–14460 cm−1 at room temperature with a resolution of 0.03 cm−1 and a threshold sensitivity in absorption of 10−6 cm−1. With a multipass cell, the volume of which was 3 L and the base of which was 25 cm, a length of the absorbing layer of 10 m has been achieved. A high signal-to-noise ratio, on the order of 1000, has allowed us to detect about 700 lines of the H218O molecule, the intensities of which were as low as 10−25 cm/molecule, at 296 K. The observed lines have been attributed to eleven vibrational-rotational bands of the molecule.

Broadening and shifting of vibrational-rotational lines corresponding to the highly excited rotational states of the water molecule

Self-pressure-induced, as well as argon- and nitrogen-induced, broadening γ and shifting δ coefficients of vibrational-rotational lines of the water molecule have been calculated. The asymptotic behavior of the coefficients γ and δ at J → 42 and Ka → J has been studied. For the calculation of the parameters γ and δ, we used the wave functions obtained from the analysis of highly excited rotational states of the H2O molecule with the maximal ever observed values of rotational quantum numbers Jmax = 42, Kamax = 32. Rotational states were analyzed in the method of effective Hamiltonians using generating functions for the first eight vibrational states of the molecule.

Isotopically invariant dunham parameters and the potential function of the HCl molecule

The isotopically invariant Dunham parameters Umj, ΔmjH and ΔmjCl were determined by simultaneously fitting the line centers of vibration-rotation transitions of six isotopic HCl forms in the ground electronic state. Fitting included relations between Umj values. The parameters of the isotopically invariant potential of HCl were determined using independent Um0 and Um1 values. The contributions to the vibrational terms of H35Cl caused by violation of the Born-Oppenheimer approximation were calculated.

RKR potentials of isotopologues of the CO molecule

The RKR potentials of nine isotopologues of the carbon monoxide molecule in the ground electronic state are calculated on the basis of new values of the Dunham spectroscopic parameters Ymj up to the v = 41 vibrational level. The potential of the main isotopologue 12C16O determined at separate points is approximated by expansions in variables zD = (r−re)/re and zS = (r − re)/r. The expansion coefficients are presented.

LED-based Fourier transform spectroscopy of H216O in the range 15500–16000 cm−1

The spectrum of H218O in the range 15000–15700 cm−1 has been recorded for the first time on a Fourier-transform spectrometer using a high-brightness light-emitting diode as a radiation source. The measurements have been conducted at room temperature with a resolution of 0.05 cm−1. A threshold sensitivity in absorption of 2 × 10−7 cm−1 has been achieved due to both the use of a light-emitting diode and optimization of the multipass cell with a base length of 60 cm, which ensured a 19.2-m length of the absorbing layer. A high signal-to-noise ratio (S/N = 2000–10000) made it possible to record about 670 water-vapor lines with intensities of 1.0 × 10−26–2.2 × 10–24 cm/mol at 296 K. The energies of 265 vibrational-rotational levels of the H218O molecule are determined and attributed to seven vibrational states, namely, (033), (113), (212), (231), (311), (330), and (410).