Surface and Bulk Diffusion on Single-Crystal Ice and Acid Hydrate Multilayers

对与大气有关的小分子在冰上和冰中扩散的研究是由分析和表面化学计划以及大气化学计划联合支持的这一研究项目的主题。激光共振解吸法将被用来探测ClONO2、HOCl3、HNO3和HCl在表面以及在超高真空装置上制备的冰和酸水合物多层膜中的扩散。了解扩散过程和扩散速率的知识对于了解极地平流层云的非均相化学很重要，这种云将稳定的含有卤素的储藏分子转化为活性卤素物种，从而催化破坏平流层中的臭氧。这项工作还将提供有关分子固体上和分子内扩散过程的新的基本信息。为了了解氯氟烃推进剂和制冷剂等人造化学品消耗平流层臭氧的详细机制和速度，必须了解这些分子及其分解产物在平流层表面和大部分冰粒中扩散的速度和机制。获得这一认识是本研究项目的目标。使用首席研究人员以前开发的激光解吸方法，将检查这一扩散过程的细节。这些信息将有助于开发大气化学模型，这将有助于科学家为平流层臭氧层耗尽等问题提出解决方案。

The investigation of the diffusion of small, atmospherically relevant molecules on and in ice is the subject of this research project supported jointly by the Analytical and Surface Chemistry Program and the Atmospheric Chemistry Program. Laser resonant desorption methods will be used to probe the diffusion of ClONO2, HOCl, HNO3 and HCl on the surface and in the bulk of ice and acid hydrate multilayers produced and characterized in an ultra high vacuum apparatus. An understanding of the diffusion process and a knowledge of diffusion rates is important to developing an understanding of the heterogeneous chemistry of polar stratospheric clouds that convert stable halogen containing reservoir molecules into active halogen species which destroy ozone catalytically in the stratosphere. This work will also provide new basic information about the diffusion process on and in molecular solids. In order to understand the detailed mechanisms and rates of stratospheric ozone depletion by man made chemicals such as chlorofluorocarbon propellants and refrigerants, it is important to know about the rates and mechanisms of diffusion of these molecules and their decomposition products on the surfaces and in the bulk of the ice particles which exist in the stratosphere. Obtaining this understanding is the goal of this research project. Using laser desorption methods developed previously by the principal investigator, the details of this diffusion process will be examined. This information will help in developing models of the chemistry of the atmosphere which will aid scientists in proposing solutions for problems such as the depletion of the ozone layer in the stratosphere.