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

研究与大气相关的小分子在冰上和冰中的扩散是本研究项目的主题，该研究项目由分析与表面化学项目和大气化学项目共同支持。本文将采用激光共振解吸法探测在超高真空装置中制备和表征的冰和酸水合物多层材料表面和内部ClONO2、HOCl、HNO3和HCl的扩散。了解扩散过程和扩散速率对于理解极地平流层云的非均质化学非常重要，这些云将含有稳定卤素的储层分子转化为活性卤素，从而催化破坏平流层中的臭氧。这项工作还将为分子固体表面和内部的扩散过程提供新的基础信息。为了了解诸如氯氟烃推进剂和制冷剂等人造化学品使平流层臭氧耗损的详细机制和速率，必须了解这些分子及其分解产物在平流层表面和大部分存在的冰粒中扩散的速率和机制。获得这种理解是本研究项目的目标。使用激光解吸方法开发以前的主要研究者，这一扩散过程的细节将被检查。这些资料将有助于发展大气化学模型，这将有助于科学家提出解决诸如平流层臭氧层损耗等问题的办法。

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.