The high resolution absorption spectrum of jet-cooled CS2 between 50500 and 65500 cm(-1)

The absorption spectrum of jet-cooled CS2 has been photographed between 50 500 and 65 500 cm(-1) at a resolution limit of 0.008 Angstrom. Ab initio calculations are carried out to estimate the energy of the lower Rydberg states of ionic cores ... 2 pi(g)(3), ... 2 pi(u)(3), and ... 5 sigma(u), as well as those belonging to the doubly excited configuration ... 2 pi(g)(2)3 pi(u)(2). Assigned electronic states include the ... 2 pi(g)(3)4s (1) Pi(g) , (with vibronic bands 2(1)(0) and 2(0)(n), n = 1,3,5,7, observed thanks to a concurrent of Herzberg-Teller intensity borrowing and Renner-Teller intensity redistribution) and ... 2 pi(g)(3)4p (1,3)Pi(u), and (3) Sigma(u)(-) (observed bands being the electronic origin, 1(0)(1) and 2(0)(2) bands). Model calculations of Reener-Teller in the (1) Pi states are performed leading to epsilon and omega(2) parameter values. In the case of the 4p (1) Pi(u) state, Fermi resonance between the upsilon'(1) = 1 level and the upsilon'(2) = 2 RT-split levels of Pi(u) vibronic symmetry, is also taken into account, The rotational band contours of the origin bands of the whole set of the ... 2 pi(g)(3)4p Rydberg transitions excited by one or three photons are calculated using a model based on Hund's case (e) representation. The calculated band contours, wave numbers, and relative intensities are in excellent agreement with the observations of the present vuv absorption spectrum, and the multiphoton(3+1) ionization spectrum of Baker et al. [J. Chern. Phys. 103, 2436 (1995)] provided that in the latter, the (1) Sigma(u)(+) state is reassigned as (3) Sigma(u)(-). Fitted values of the 4p quantum defects and of the 4p pi((1) Sigma(u)(+))/4p sigma((1) Pi(u)) transition moment ratio are found to be perfectly consistent with the ab initio calculation results. Possible assignments of 3d transitions in the present and previous vuv absorption spectra as well as in recent multiphoton (1+1')+1) ionization spectra of CS2 below 65 500 cm(-1) are also discussed in the light of the present calculation results. (C) 1996 American Institute of Physics.