Time-Resolved EUV-Probed Surface Chemistry

科罗拉多大学的Margaret Murnane教授由分析和表面化学项目资助，利用极紫外（EUV）和x射线辐射研究表征良好的吸附物/表面系统的飞秒动力学。通过高谐波产生的新的短波长的光将被用来访问吸附质的核心水平。特别是，当单晶铂（111）上的氧受到长度为5飞秒的激光脉冲时，电荷转移动力学将被研究。同样，在同一晶面上一氧化碳的氧化也要进行检查。由于具有足够通量和短脉冲持续时间的超快x射线源直到最近才可用，因此通过光电发射测量表面反应物在不同平衡态之间演变的动力学的能力非常有限。飞秒和皮秒时间尺度适合于表面反应下的基本原子运动。这项工作将增加我们对表面电荷转移过程的理解。电荷转移是一种化学现象，存在于电化学和生物化学等多种过程中。飞化学领域最近被1999年诺贝尔化学奖认定为前沿领域。

Professor Margaret Murnane of the University of Colorado is funded by the Analytical and Surface Chemistry Program to study femtosecond dynamics of well-characterized adsorbate/surface systems using extreme ultraviolet (EUV) and x-ray radiation. New shorter wavelengths of light produced through high harmonic generation will be utilized to access adsorbate core levels. In particular, charge transfer dynamics will be studied when oxygen on single crystal platinum (111) is subjected to laser pulses five femtoseconds in length. Also, the oxidation of CO on this same crystal face is to be examined. The ability to measure dynamics of a surface reactant as it evolves between different equilibrium states by photoemission has been very restricted, because ultrafast x-ray sources with sufficient flux and short pulse duration have not been available until very recently. The femtosecond and picosecond timescales are appropriate to the basic atomic motions underlying surface reactions.The work will increase our understanding of charge transfer processes on surfaces. Charge transfer is a chemical phenomenon underlying diverse processes such as electrochemistry and biochemistry. The area of femtochemistry was recently recognized as a frontier by the Nobel Prize in Chemistry in 1999.