A comparative high-resolution study of predissociation linewidths in the Schumann-Runge bands of O2

High-resolution Fourier-transform extreme ultraviolet photoabsorption spectroscopy of 14N15N

The first comprehensive high-resolution photoabsorption spectrum of (14)N(15)N has been recorded using the Fourier-transform spectrometer attached to the Desirs beamline at the Soleil synchrotron. Observations are made in the extreme ultraviolet and span 100 000-109 000 cm(-1) (100-91.7 nm). The observed absorption lines have been assigned to 25 bands and reduced to a set of transition energies, f values, and linewidths. This analysis has verified the predictions of a theoretical model of N(2) that simulates its photoabsorption and photodissociation cross section by solution of an isotopomer independent formulation of the coupled-channel Schrödinger equation. The mass dependence of predissociation linewidths and oscillator strengths is clearly evident and many local perturbations of transition energies, strengths, and widths within individual rotational series have been observed.

The application of a vacuum-ultraviolet Fourier transform spectrometer and synchrotron-radiation source to measurements of bands of NO. VII. The final report

Photoabsorption measurements of NO bands have been made by vacuum-ultraviolet Fourier transform spectrometry with a resolution of 0.12 cm(-1) in the wavelength region of 166.2-196.2 nm. Accurate line positions are obtained for the delta(upsilon,0) bands with upsilon=2, 3, the epsilon(upsilon,0) bands with upsilon=2, 3, and the beta(upsilon,0) bands with upsilon=10,12,14. Absolute term values are found for the corresponding upper levels C(2,3), D(2,3), and B(10,12,14). Accurate rotational line integrated cross sections have also been obtained for the lines in these bands. Integrated cross sections reported in our earlier papers [J. Chem. Phys. 109, 1751 (1998); 112, 2251 (2000); 115, 3719 (2001); 116, 155 (2002); 117, 10621 (2002); 119, 8373 (2003)] have been revised, and the results reported here comprise the delta(upsilon,0) bands with upsilon=0-3, the epsilon(upsilon,0) bands with upsilon=0-3, the beta(upsilon,0) bands with upsilon=6,7,9-12,14, and the gamma(3,0) band. For each band, the band oscillator strength is obtained from the sum of the line strengths of all rotational lines, and these are compared with other published values.

Pressure broadening and fine-structure-dependent predissociation in oxygen BΣu−3, v=0

Both laser-induced fluorescence and cavity ring-down spectral observations were made in the Schumann-Runge band system of oxygen, using a novel-type ultranarrow deep-UV pulsed laser source. From measurements on the very weak (0,0) band pressure broadening, pressure shift, and predissociation line-broadening parameters were determined for the B 3sigma(u)-, v = 0,F(i) fine-structure components for various rotational levels in O2. The information content from these studies was combined with that of entirely independent measurements probing the much stronger (0,10), (0,19), and (0,20) Schumann-Runge bands involving preparation of vibrationally excited O2 molecules via photolysis of ozone. The investigations result in a consistent set of predissociation widths for the B 3sigma(u)-, v = 0 state of oxygen.

Vibrational energy transfer in O2(X 3sigma(g)-, upsilon=2,3) + O2 collisions at 330 K

Vibrational relaxation of O2(X 3sigma(g)-, upsilon=2,3) by O2 molecules is studied via a two-laser approach. Laser radiation at 266 nm photodissociates ozone in a mixture of molecular oxygen and ozone. The photolysis step produces vibrationally excited O2(a 1delta(g)) that is rapidly converted to O2(X 3sigma(g)-, upsilon=2,3) in a near-resonant adiabatic electronic energy-transfer process involving collisions with ground-state O2. The output of a tunable 193-nm ArF laser monitors the temporal evolution of the O2(X 3sigma(g)-, upsilon=2,3) population via laser-induced fluorescence detected near 360 nm. The rate coefficients for the vibrational relaxation of O2(X 3sigma(g)-, upsilon=2,3) in collision with O2 are 2.0(-0.4)(+0.6) x 10(-13) cm3 s(-1) and (2.6+/-0.4) x 10(-13) cm3 s(-1), respectively. These rate coefficients agree well with other experimental work but are significantly larger than those produced by various semiclassical theoretical calculations.