Ultraviolet absorption spectrum of cyclic CS2 in solid Ar

Linear CS2 dispersed in solid Ar was irradiated with an excimer laser at 193 nm to form cyc-CS2 of which infrared (IR) identification and theoretical calculations were reported previously. We recorded an ultraviolet (UV) absorption spectrum with two progressions (330–380 nm) that correlate well with variations in intensities of IR absorption of cyc-CS2 upon photolysis of linear CS2 at various stages; hence we assign it to electronic transitions of cyc-CS2. Based on theoretical calculations and vibronic symmetry, we tentatively assign progression A to transition 21B2 ← X1A1 and progression B to 21B1 ← X1A1 of cyc-CS2.