Investigations into the Laser Ablation Process and the Pursuit of New Chemical Applications

弗吉尼亚大学的W·莱斯特·S·安德鲁斯得到了实验物理化学计划的支持，继续他的基质隔离傅里叶变换红外活性物种的研究。在以前的工作中，激光烧蚀是用来产生热原子的，这些热原子随后在基质上或附近反应形成感兴趣的物种。在这个奖项中，重点是a)了解激光烧蚀过程本身和b)寻求新的化学应用。例如，在前一种情况下，PI将调查激光烧蚀的Fe与O2反应生成OFeO的反应的激活能的来源，这是一种不发生在热上的反应。激活能是由于超额动能、涉及亚稳态的电子激发还是来自激光等离子体的辐射？增加涉及磁场或电场的装置将允许操纵带电物种，这应该会导致对一些潜在机制的理解。将进行激光烧蚀霓虹灯基质中的铍和氧的实验，试图分离出第一种中性霓虹灯化合物NeBeO。最后，我们将尝试分离半导体生长过程中的反应中间产物。鉴于目前脉冲激光烧蚀生长半导体薄膜的兴趣，将重点介绍GaP、GaP和InSb与H_2的反应。密度泛函理论研究将与Bauschlicher合作进行，尽管本提案的重点是实验方面。脉冲激光烧蚀正迅速成为一种非常重要的物理技术，目前应用于等离子体物理、分析化学和超导体生长等多个领域。更好地了解激光消融过程将有助于促进这项技术的进一步应用。

W. Lester S. Andrews of the University of Virginia is supported by the Experimental Physical Chemistry Program to continue his matrix-isolation Fourier Transform Infrared studies of reactive species. In previous work, laser ablation was used to generate hot atoms which subsequently reacted at or near the matrix to form the species of interest. In this award, the emphasis is on a) understanding the laser ablation process itself and b) pursuing new chemical applications. In the former case, e.g., the PI will investigate the source for the activation energy of the reaction in which laser ablated Fe reacts with O2 to form OFeO, a reaction that does not occur thermally. Is the activation energy due to excess kinetic energy, electronic excitation involving metastables or radiation from the laser plasma? Additions to the apparatus involving magnetic or electric fields will allow manipulation of charged species, which should lead to an understanding of some of the underlying mechanisms. Laser ablation experiments with beryllium and oxygen in a neon matrix will be carried out in an attempt to isolate the first neutral neon compound NeBeO. Finally, the isolation of reaction intermediates in semiconductor growth processes will be attempted. Given current interest in pulsed laser ablation to grow semiconductor thin films, reactions of GaAs, GaP and InSb with H2 will be emphasized. Density functional theoretical studies will be done in collaboration with Bauschlicher, although the emphasis in this proposal is on the experimental aspects. Pulsed-laser ablation is rapidly becoming an extremely important physical technique and is currently employed in such diverse areas as plasma physics, analytical chemistry and the growth of superconductors. Better understanding of the laser ablation process would help foster further applications of this technology.