Real-time detection of S(¹D₂) photofragments produced from the ¹B₂(¹Σ_u⁺) state of CS₂ by vacuum ultraviolet photoelectron imaging using 133 nm probe pulses

Ultrafast photodissociation dynamics from the ¹B₂(¹Σ_u⁺) state of CS₂ are studied by time-resolved photoelectron imaging using the fourth (4ω, 198 nm) and sixth (6ω, 133 nm) harmonics of a femtosecond Ti:sapphire laser. The ¹B₂ state of CS₂ was prepared with the 4ω pulses, and subsequent dynamics were probed using the 6ω vacuum ultraviolet (VUV) pulses. The VUV pulses enabled real-time detection of S(¹D₂) photofragments, produced via CS₂*(¹B₂(¹Σ_u⁺)) → CS(X¹Σ⁺) + S(¹D₂). The photoionization signal of dissociating CS₂*(¹B₂(¹Σ_u⁺)) molecules starts to decrease at about 100 fs, while the S(¹D₂) fragments appear with a finite (ca. 400 fs) delay time after the pump pulse. Also discussed is the configuration interaction of the ¹B₂(¹Σ_u⁺) state based on relative photoionization cross-sections to different cationic states.