Selectively exciting desorption Reactions of molecules adsorbed on surfaces can be induced by injecting electrons from the tip of a scanning tunneling microscope. Rusimova et al. show that for the tip-induced desorption of toluene molecules from a silicon surface, two activation channels exist: One is invariant, but the other depends on the height of the tip above the surface. When the tip is very close to the molecule, it can quench the excitation. The decreased lifetime, in turn, decreases the desorption probability. Science, this issue p. 1012 The desorption of toluene from a silicon surface can be regulated by excitation with a scanning tunneling microscope tip. The key to controlling reactions of molecules induced with the current of a scanning tunneling microscope (STM) tip is the ultrashort intermediate excited ionic state. The initial condition of the excited state is set by the energy and position of the injected current; thereafter, its dynamics determines the reaction outcome. We show that a STM can directly and controllably influence the excited-state dynamics. For the STM-induced desorption of toluene molecules from the Si(111)-7x7 surface, as the tip approaches the molecule, the probability of manipulation drops by two orders of magnitude. A two-channel quenching of the excited state is proposed, consisting of an invariant surface channel and a tip height–dependent channel. We conclude that picometer tip proximity regulates the lifetime of the excited state from 10 femtoseconds to less than 0.1 femtoseconds.

中文翻译：

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调节单个分子的飞秒激发态寿命

选择性激发解吸 吸附在表面的分子的反应可以通过从扫描隧道显微镜的尖端注入电子来引起。鲁西莫娃等。表明对于尖端诱导的甲苯分子从硅表面解吸，存在两个激活通道：一个是不变的，但另一个取决于尖端在表面上方的高度。当尖端非常靠近分子时，它可以淬灭激发。降低的寿命反过来又降低了解吸概率。科学，这个问题 p。1012 甲苯从硅表面的解吸可以通过扫描隧道显微镜尖端的激发进行调节。控制由扫描隧道显微镜 (STM) 尖端电流引起的分子反应的关键是超短中间激发离子态。激发态的初始条件由注入电流的能量和位置决定；此后，其动力学决定了反应结果。我们表明 STM 可以直接且可控地影响激发态动力学。对于 STM 诱导的甲苯分子从 Si(111)-7x7 表面解吸，当尖端接近分子时，操纵概率下降了两个数量级。提出了激发态的双通道淬灭，由不变的表面通道和尖端高度相关的通道组成。我们得出结论，皮米尖端接近度将激发态的寿命从 10 飞秒调节到小于 0.1 飞秒。我们表明 STM 可以直接且可控地影响激发态动力学。对于 STM 诱导的甲苯分子从 Si(111)-7x7 表面解吸，当尖端接近分子时，操纵概率下降了两个数量级。提出了激发态的双通道淬灭，由不变的表面通道和尖端高度相关的通道组成。我们得出结论，皮米尖端接近度将激发态的寿命从 10 飞秒调节到小于 0.1 飞秒。我们表明 STM 可以直接且可控地影响激发态动力学。对于 STM 诱导的甲苯分子从 Si(111)-7x7 表面解吸，当尖端接近分子时，操纵概率下降了两个数量级。提出了激发态的双通道淬灭，由不变的表面通道和尖端高度相关的通道组成。我们得出结论，皮米尖端接近度将激发态的寿命从 10 飞秒调节到小于 0.1 飞秒。提出了激发态的双通道淬灭，由不变的表面通道和尖端高度相关的通道组成。我们得出结论，皮米尖端接近度将激发态的寿命从 10 飞秒调节到小于 0.1 飞秒。提出了激发态的双通道淬灭，由不变的表面通道和尖端高度相关的通道组成。我们得出结论，皮米尖端接近度将激发态的寿命从 10 飞秒调节到小于 0.1 飞秒。