Analysis of a ¹Δ_u–¹Σ_g⁺ Transition of CS₂ in the Near Ultraviolet

Abstract

The strongest features of the gas-phase absorption spectrum of CS2 in the region 2900–3300 Å (Kleman's V system) are shown to belong to a 1B2–1Σg+ transition, where the 1B2 state correlates with the upper Renner–Teller component of the π → π* 1Δu state of the linear molecule. The barrier to linearity is about 1300 cm−1, and the structure of the molecule in the zero-point level is r(C–S) = 1.544 ± 0.006 Å, [Formula: see text]. Transitions to the lower Renner–Teller component, 1A2(1Δu), have been identified in the region 3340–3500 Å: these consist of a progression of vibronic Δ–Δ bands and a weaker progression of Π–Π bands. This is a new type of electronic transition, which does not appear in cold absorption, but whose 'hot' bands derive an amount of intensity proportional to K2 through Renner–Teller mixing (in this case from the V system). The bands of both systems are very severely perturbed: possible causes of the perturbations are discussed.

Using the Ultraviolet and Visible spectrum of Comet 122P/de Vico to Identify the Parent Molecule CS 2

“…This R p l/Dl p 60,000 is much greater than the resolution of the CS 2 laboratory emis- The vacuum wavenumbers are from Kasahara et al (1984), except for those labeled with an asterisk, which are from Bernath et al (1981). c The assignments of the excited bands from which the emission lines have been observed are those reported by Ochi et al (1987), Jungen et al (1973), andKleman (1963).…”

“…There are many polyatomic molecules with strong bonding that undergo similar shifts, although they have not been as extensively studied in supersonic molecular beams as CS 2 . The near-ultraviolet spectroscopy (3800-2900 ; Kleman 1963;Jungen et al 1973;Ochi et A al. 1987) and the laser-excited fluorescence emission spectra of this molecule (Kasahara et al 1984;Bernath et al 1981;Silver & McKeever 1976;Dueñas Fañ anás & Cabello 1983;Lambert & Kimbel 1973;Matsuzaki et al 1982;Liou et al 1992;Vasudev 1982) have been investigated by many authors over the past 60 years.…”

“…The lines and their assignments are shown in Table 1 along with the name of the vibrational bands as given by Jungen et al (1973) and Kleman (1963) in their classic studies on CS 2 . Most of the observed emission lines arise from the strong features in the absorption spectrum obtained in a supersonic molecular beam, i.e., the 10V and 15V bands (Kasahara et al 1984).…”

“…This is what was expected since the upper levels from these absorptions should be the most populated. Emissions from triplet states, such as transitions within the electronic band system designated as R (Jungen et al 1973;Ochi et al 1987), are also expected to occur in a collision-free environment of the coma of a comet because intersystem crossing from the singlet to triplet state should be rapid. The CS 2 comet features near 25,310 cm may be blended with two C 3 emission Ϫ1 lines (Balfour et al 1994).…”

Two-Photon Dissociation Study of CS2 Using Ion Imaging

“…29,30 Baker et al 31 and Morgan et al 32 have studied the structure of CS 2 near 69 399 cm -1 Via two-photon and three-photon excitations. Specifically Morgan et al 32 have assigned a broad transition at 69414 cm -1 to linear 3 Π g Rydberg state, while higher resolution measurements of Baker et al 31 have observed transitions at energies of 69 330 cm -1 (peak E) assigned to the 3 Σ g -Rydberg state, 69 369 cm -1 (peak F, unassigned), 69 446 cm -1 (peak G) assigned to 1 Π g / 1 ∆ g Rydberg states, and the origin band (0 0 0 ) for a transition to a 1 Σ g + Rydberg state has been reported at 69 861 cm -1 .…”