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Kinetics and Thermochemistry Studies of Carboxylic and Other Acids Using Negative Ion Proton Transfer Mass Spectrometry (NI-PTMS)

使用负离子质子转移质谱 (NI-PTMS) 对羧酸和其他酸进行动力学和热化学研究

基本信息

批准号：
0803016
负责人：
Solomon Bililign
金额：
$ 31.34万
依托单位：
North Carolina Agricultural & Technical State University
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2008
资助国家：
美国
起止时间：
2008-05-01 至 2012-04-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=0803016&HistoricalAwards=false
关键词：
Kinetics Thermochemistry Studies Carboxylic Other

项目摘要

This project is centered around 1) the development of Negative Ion Proton Transfer Mass Spectrometry (NI-PTRMS) for the detection of carboxylic acids in the atmosphere and 2) an improved understanding of the gas phase ion chemistry on which the method relies. NI-PTRMS involves selective ionization of acidic species via transfer of a proton to an acetate ion. Since acetic acid is the weakest of the common carboxylic acids, acetate ions will react with all gas-phase carboxylic acids, and with strong inorganic acids as well. Several schemes, such as the high-pressure radioactive ionization of selected starting materials (acetic esters or anhydrides, for example) will be explored and evaluated for their potential to produce an intense, cluster-free source of the desired ion. The relative gas-phase acidities of simple carboxylic acids (propionic, butyric, and others) and some isotopomers of acetate will be measured. Thermochemistry and reaction rates of the first hydrate of acetate ion with carboxylic acids will also be determined.Broader scientific impacts include applications to air quality and climate change because carboxylic acids are key intermediates in the formation of both tropospheric ozone and aerosols. Education plans include participation by both undergraduate and graduate students from communities that are underrepresented in the atmospheric sciences.

该项目的中心是1)负离子质子转移质谱仪(NI-PTRMS)的发展，用于检测大气中的羧酸；2)提高对该方法所依赖的气相离子化学的理解。Ni-PTRMS包括通过将质子转移到乙酸根离子来选择性电离酸性物种。因为醋酸是常见的羧酸中最弱的一种，所以醋酸根离子会与所有的气相羧酸反应，也会与强的无机酸反应。将探索和评估几种方案，例如对选定的起始材料(例如醋酸酯或酸酐)进行高压放射性电离，以期产生所需离子的强而无团簇的源。简单的羧酸(丙酸、丁酸和其他)和一些醋酸酯的同位异构体的相对气相酸度将被测量。还将确定醋酸根离子的第一水合物与羧酸的热化学和反应速率。更广泛的科学影响包括应用于空气质量和气候变化，因为羧酸是形成对流层臭氧和气溶胶的关键中间体。教育计划包括来自大气科学中代表性不足的社区的本科生和研究生的参与。