The vacuum-ultraviolet photoinduced dynamics of cyclopropane (C₃H₆) were studied using time-resolved photoelectron spectroscopy (TRPES) in conjunction with ab initio quantum dynamics simulations. Following excitation at 160.8 nm, and subsequent probing via photoionization at 266.45 nm, the initially prepared wave packet is found to exhibit a fast decay (<100 fs) that is attributed to the rapid dissociation of C₃H₆ to ethylene (C₂H₄) and methylene (CH₂). The photodissociation process proceeds via concerted ring opening and C–C bond cleavage in the excited state. Ab initio multiple spawning simulations indicate that ring-opening occurs prior to dissociation. The dynamics simulations were subsequently employed to simulate a TRPES spectrum, which was found to be in excellent agreement with the experimental result. On the basis of this agreement, the fitted time constants of 35 ± 20 and 57 ± 35 fs were assigned to prompt (i) dissociation on the lowest-lying excited state, prepared directly by the pump pulse, and (ii) non-adiabatic relaxation from higher-lying excited states that lead to delayed dissociation, respectively.

中文翻译：

---

最小的环，环丙烷的真空紫外激发态动力学。二。时间分辨光电子能谱和从头算动力学

使用时间分辨光电子能谱（TRPES）结合从头算量子动力学模拟，研究了真空紫外光诱导的环丙烷（C ₃ H ₆）的动力学。在160.8 nm激发后，随后在266.45 nm通过电离探测，发现最初制备的波包表现出快速衰减（<100 fs），这归因于C ₃ H ₆迅速分解为乙烯（C ₂ H ₄）和亚甲基（CH ₂）。光解离过程通过一致的开环和处于激发态的C–C键断裂而进行。从头算多次产卵模拟表明开环发生在解离之前。随后采用动力学模拟来模拟TRPES光谱，发现该光谱与实验结果非常吻合。根据该协议，将拟合的时间常数35±20和57±35 fs分配给提示（i）在最低激发态下的解离，该状态由泵浦脉冲直接准备，并且（ii）非绝热来自较高激发态的弛豫分别导致延迟解离。