Ultrafast charge, energy and structural dynamics in molecules are driven by the topology of the multidimensional potential energy surfaces that determines the coordinated electronic and nuclear motion. These processes are also strongly influenced by the interaction with the molecular environment, making very challenging a general understanding of these dynamics on a microscopic level. Here we use electrospray and mass spectrometry technologies to produce isolated molecular ions with a controlled micro-environment. We measure ultrafast photo-induced ππ*-πσ* dynamics in tryptophan species in the presence of a single, charged adduct. A striking increase of the timescale by more than one order of magnitude is observed when changing the added adduct atom. A model is proposed to rationalize the results, based on the localized and delocalized effects of the adduct on the electronic structure of the molecule. These results offer perspectives to control ultrafast molecular processes by designing the micro-environment on the Angström length scale.

分子中的超快电荷、能量和结构动力学由决定协调电子和核运动的多维势能面的拓扑结构驱动。这些过程也受到与分子环境相互作用的强烈影响，使得在微观层面上对这些动力学的一般理解非常具有挑战性。在这里，我们使用电喷雾和质谱技术在受控的微环境中产生分离的分子离子。我们在存在单个带电加合物的情况下测量色氨酸物种中的超快光诱导 ππ*-πσ* 动力学。当改变添加的加合物原子时，观察到时间尺度显着增加了一个数量级以上。提出了一个模型来使结果合理化，基于加合物对分子电子结构的局部和离域效应。这些结果为通过在埃长度尺度上设计微环境来控制超快分子过程提供了前景。