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.