Comment on predissociation of O2 in the B state

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Predissociation of oxygen in the B 3Σ-u state

The predissociation linewidths and level shifts of vibrational levels of three oxygen isotopic molecules 16O 2, 16O 18O, and 18O 2 arising from the interactions of the B 3Σ u -~ state with the four repulsive states 5Π u, 3Σ u +, 3Π u, and 1Π u, have been calculated. A set of parameters characterizing these interactions has been determined. Good agreement between calculated and experimental predissociation widths and shifts has been obtained for all the three isotopic molecules. © 1992 American Institute of Physics.published_or_final_versio

Fourier transform spectroscopy and cross section measurements of the Herzberg III bands of O2 at 295 K

The absorption bands of the Herzberg III of O2 at 295 K were measured using Fourier transform spectrometer. The rotational line positions were determined, as well as the rotational line strengths and the branching ratios. The band oscillator strengths from the sum of the strengths of the individual rotational lines were shown.published_or_final_versio

Isotopic dependence of predissociation linewidths in the Schumann-Runge bands of oxygen

It is demonstrated that, according to semi-classical theory, the isotopic dependence of the predissociation linewidths in the Schumann-Runge bands of oxygen cannot be removed by simple scaling of the reduced mass. This is in contrast to the isotopic dependence of the predissociated vibrational energy levels. ©1995 American Institute of Physics.published_or_final_versio

Rotational dependence of the predissociation linewidths of the Schumann-Runge bands of O2

The predissociation linewidths of vibrational levels v=0-12 for 16O 2, 16O 18O, and 18O 2 molecules in the B 3Σ u - state with rotational quantum numbers N≤20 have been calculated taking into account the spin-orbit interactions of the B 3Σ u - state with the 5Π u, 3Σ u +, 3Π u, and 1Π u states, and the rotational coupling with the 3Π u, state. The predissociation linewidths exhibit systematic variations with rotational quantum number for different vibrational levels. Good agreement between most of the calculated and experimental linewidths has been obtained for all three isotopic molecules, with the exception of the set of linewidths of 16O 2 for v=0 and 2. The agreement can be improved by adjustment of the 1Π u potential and the strength of the spin-orbit interaction between the B 3Σ u - and 1Π u states. © 1993 American Institute of Physics.published_or_final_versio

The application of a VUV Fourier transform spectrometer and synchrotron radiation source to measurements of: II. The δ(1,0) band of NO

Line-by-line photoabsorption cross-sections of the NO δ(1,0) band were measured with the VUV Fourier transform spectrometer from Imperial College, London, using synchrotron radiation at Photon Factory, KEK, Japan, as a continuum light source. The analysis of the NO δ(1,0) band provides accurate rotational line positions and term values as well as the photoabsorption cross-sections. The molecular constants of the C(1)2 II level are found to be T0 = 54 690.155±0.03 cm–1, Bv = 1.944 06±0.000 62 cm–1, Dv = (5.91±0.42)×10–5 cm–1, AD = –0.0187±0.0050 cm–1, p = –0.0189±0.0037 cm–1, and q = –0.015 21±0.000 20 cm–1. The sum of the line strengths for all rotational transitions of the NO δ(1,0) band is determined as 4.80×10–15 cm2 cm–1, corresponding to a band oscillator strength of 0.0054±0.0003.published_or_final_versio

Predissociation linewidths of the (3,0)-(11,0) Schumann-Runge absorption bands of 18O2 and 16O 18O in the wavelength region 180-196 nm

Predissociation linewidths of the (3,0)-(11,0) Scbumman-Runge bands of 18O 2 and 16O 18O in the wavelength region 180-196 nm have been obtained from the published measurements of the absolute absorption cross sections of Yoshino et al. [Planet. Space Sci. 36, 1201 ( 1988); 37, 419 (1989)] and spectroscopic constants of these molecules of Cheung et al. [J. Mol. Spectrosc. 131, 96 ( 1988); 134, 362 (1989)]. The linewidths are determined as parameters in the nonlinear least-squares fitting of calculated to measured cross sections. Predissociation maxima are found at upper vibrational levels with v′ = 4 ,7, and 10 for 18O 2 and for 16O 18O. Our predissociation linewidths are mostly greater than previous experimental values for both isotopic molecules. © 1990 American Institute of Physics.published_or_final_versio

The application of a VUV Fourier transform spectrometer and synchrotron radiation source to measurements of: I. the β(9,0) band of NO

State-of-the-art models of the vacuum ultraviolet (VUV) absorbing properties of the atmosphere call for absorption cross sections with detail on the scale of the Doppler widths. As a consequence, spectroscopic data at resolving powers of the order of 10 6 are needed. To meet these requirements in the vacuum ultraviolet region, we have used the VUV Fourier transform spectrometer from Imperial College, London, at the synchrotron radiation facility at Photon Factory, KEK, Japan, to measure photoabsorption cross sections of NO from 195 to 160 nm, and of O 2 from 185 to 175 nm. The analysis of the β(9,0) band (B 2Π r-X 2Π r) of NO provides accurate rotational line positions and term values. Molecular constants of the B(9) 2Π level are T 0=54205.097±0.012cm -1, A=45.320±0.021cm -1, B υ=1.01672±0.00016cm -1, D υ=(10.61±0.32)×10 -6cm -1, and A D=0.00122±0.00011cm -1. The rotational line strengths and the branching ratios are also presented. The band oscillator strength is obtained as f=2.65×10 -4. © 1998 American Institute of Physics.published_or_final_versio

Predissociation linewidths of the (1,0)-(12,0) Schumann-Runge absorption bands of O2 in the wavelength region 179-202 nm

A nonlinear least-squares method of retrieving predissociation linewidths from the experimental absolute absorption cross sections of Yoshino et al. [Planet. Space Sci. 31, 339 (1983)] has been applied to the (1,0)-(12,0) Schumann-Runge bands of oxygen. Predissociation linewidths deduced for the Schumann-Runge bands are larger than the theoretical predictions of Julienne [J. Mol. Spectrosc. 63, 60 (1976)] and the latest measurements of Lewis et al. [J. Quant. Spectrosc. Radiat Transfer 36, 187 (1986)]. The larger linewidths found will have an impact on calculations of solar flux penetration into the Earth's atmosphere and of the photodissociation rates of trace species in the upper atmosphere. Systematic variation of predissociation linewidths with rotational quantum number is observed in the bands (v′,0) with v′ = 6, 8, 9, 11, and 12. © 1990 American Institute of Physics.published_or_final_versio