Beyvers Stephanie, Ohtsuki Yukiyoshi, Saalfrank Peter
Institut für Chemie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, D-14476 Potsdam-Golm, Germany.
J Chem Phys. 2006 Jun 21;124(23):234706. doi: 10.1063/1.2206593.
The question as to whether state-selective population of molecular vibrational levels by shaped infrared laser pulses is possible in a condensed phase environment is of central importance for such diverse fields as time-resolved spectroscopy, quantum computing, or "vibrationally mediated chemistry." This question is addressed here for a model system, representing carbon monoxide adsorbed on a Cu(100) surface. Three of the six vibrational modes are considered explicitly, namely, the CO stretch vibration, the CO-surface vibration, and a frustrated translation. Optimized infrared pulses for state-selective excitation of "bright" and "dark" vibrational levels are designed by optimal control theory in the framework of a Markovian open-system density matrix approach, with energy flow to substrate electrons and phonons, phase relaxation, and finite temperature accounted for. The pulses are analyzed by their Husimi "quasiprobability" distribution in time-energy space.
在凝聚相环境中，通过整形红外激光脉冲对分子振动能级进行态选择性布居是否可行，这一问题对于诸如时间分辨光谱学、量子计算或“振动介导化学”等众多不同领域至关重要。本文针对一个模型系统探讨了这个问题，该模型系统代表吸附在Cu(100)表面的一氧化碳。明确考虑了六个振动模式中的三个，即CO伸缩振动、CO - 表面振动和受阻平移。在马尔可夫开放系统密度矩阵方法的框架内，通过最优控制理论设计了用于“亮”和“暗”振动能级态选择性激发的优化红外脉冲，同时考虑了能量流向衬底电子和声子、相位弛豫以及有限温度。通过脉冲在时间 - 能量空间中的胡西米“准概率”分布对其进行分析。
