Different timescales during ultrafast stilbene isomerization in the gas and liquid phases revealed using time-resolved photoelectron spectroscopy

Abstract

Directly contrasting ultrafast excited-state dynamics in the gas and liquid phases is crucial to understanding the influence of complex environments. Previous studies have often relied on different spectroscopic observables, rendering direct comparisons challenging. Here, we apply extreme-ultraviolet (XUV) time-resolved photoelectron spectroscopy (TRPES) to both gaseous and liquid cis-stilbene, revealing the coupled electronic and nuclear dynamics that underlie its isomerisation. Our measurements track the excited-state wave packets from excitation along the complete reaction path to the final products. We observe coherent excited-state vibrational dynamics in both phases of matter that persist to final products, enabling the characterisation of the branching space of the S 1 -S 0 conical intersection. We observe a systematic lengthening of the relaxation time scales in the liquid phase and a red shift of the measured excited-state frequencies that is most pronounced for the complex reaction coordinate. These results characterise in detail the influence of the liquid environment on both electronic and structural dynamics during a complete photochemical transformation.

Nonadiabatic excited-state dynamics of ReCl(CO)3(bpy) in two different solvents

“…73 Recently, it has been shown that these large amplitude motions are observable in the liquid phase. 74…”

Conical Intersections in Solution with Polarizable Embedding: Integral-Exact Direct Reaction Field

“…Therefore, electronic states are not orthogonal, and transition properties are ill-defined. This, combined with root-flipping issues, renders it impossible to optimize conical intersections in solution with SS-Pol, although the solvatochromic shifts of those photochemical funnels are of great interest when analyzing ultrafast pump–probe experiments in liquid microjets. , Deriving the polarization from a state average (with fixed or dynamic weights) of the fields from multiple excited states , ameliorates some of the problems of SS-Pol, at the cost of losing the ability to fully describe a different environment polarization for each electronic state.…”

The ultrafast vibronic dynamics of ammonia's D̃ state

“…These sources have proven to be indispensible tools for studies of electronic dynamics, allowing access to high-lying electronic states as a pump, or light-induced dynamics leading to photoproducts in the electronic ground state as a probe. [30][31][32][33][34][35][36][37][38] Presented here, the high-lying Rydberg states of ammonia are revisited from previous work. 39 Making use of improved energy resolution, greater detail can be extracted, providing a far more complete description of the light-induced dynamics in these states of ammonia.…”

“…These sources have proven to be indispensible tools for studies of electronic dynamics, allowing access to high-lying electronic states as a pump, or light-induced dynamics leading to photoproducts in the electronic ground state as a probe. 30–38…”