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 time-resolved photoelectron spectroscopy to both gaseous and liquid cis-stilbene, revealing the coupled electronic and nuclear dynamics that underlie its isomerization. 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 the final products, enabling the characterization of the branching space of the S₁–S₀ conical intersection. We observe a systematic lengthening of the relaxation timescales 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 characterize in detail the influence of the liquid environment on both electronic and structural dynamics during a complete photochemical transformation.

直接对比气相和液相中的超快激发态动力学对于理解复杂环境的影响至关重要。以前的研究通常依赖于不同的光谱观测，这使得直接比较具有挑战性。在这里，我们将极紫外时间分辨光电子能谱应用于气态和液态顺式二苯乙烯，揭示了其异构化背后的耦合电子和核动力学。我们的测量跟踪从激发沿完整反应路径到最终产品的激发态波包。我们观察到持续到最终产物的物质两相中的相干激发态振动动力学，从而能够表征 S ₁ -S _{0的分支空间}锥形交叉口。我们观察到液相中弛豫时间尺度的系统延长和测量的激发态频率的红移，这对于复杂的反应坐标最为明显。这些结果详细描述了液体环境在完整的光化学转化过程中对电子和结构动力学的影响。