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

弗吉尼亚大学的W. Lester S. Andrews得到了实验物理化学项目的支持，继续他对反应物质的矩阵分离傅立叶变换红外研究。在以前的工作中，激光烧蚀被用来产生热原子，这些原子随后在基体上或附近反应，形成感兴趣的物质。在这个奖项中，重点是a)理解激光烧蚀过程本身和b)追求新的化学应用。例如，在前一种情况下，PI将研究激光烧蚀Fe与O2反应形成OFeO反应的活化能来源，这是一种不发生热反应的反应。激活能是由于过量的动能、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设备将允许操纵带电物质，这将导致对一些潜在机制的理解。利用铍和氧在氖基体中进行激光烧蚀实验，试图分离出第一个中性氖化合物NeBeO。最后，将尝试在半导体生长过程中分离反应中间体。鉴于目前对脉冲激光烧蚀生长半导体薄膜的兴趣，GaAs， GaP和InSb与H2的反应将得到强调。密度泛函理论研究将与Bauschlicher合作完成，尽管本提案的重点是在实验方面。脉冲激光烧蚀正迅速成为一项极其重要的物理技术，目前在等离子体物理、分析化学和超导体生长等各个领域都有应用。更好地了解激光烧蚀过程将有助于促进该技术的进一步应用。

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.