学术活动

LAPC学术报告

报告题目:Measuring the Drivers of Global Climate Change: Using Quantum Cascade Lasers to Quantify Atmospheric Greenhouse Gases

报告人:David Nelson

单位:Aerodyne Research, Inc. 45 Manning Rd. Billerica, MA, USA

报告时间:2012年7月18日上午9:30

地点:铁塔分部LAPC多功能会议室

报告内容:The availability of room temperature (RT), continuous wave (CW), quantum cascade (QC) lasers has enabled the development of extremely sensitive and precise laser based trace gas monitors based on the principle of infrared (IR) absorption spectroscopy.  Our measurement method is rapid sweep, direct absorption spectroscopy using long path, astigmatic Herriot cells.  Typically our measurements are performed at low pressure, with flowing samples and high time resolution (t = 0.1 seconds).  This high time resolution enables eddy covariance flux studies.  A wide variety of atmospheric molecules can be precisely and accurately monitored with this approach including some that are present in the atmosphere only at very low concentration like carbonyl sulfide ([COS] ~ 0.5 ppbv).  In this presentation I will focus on our studies of trace atmospheric species that are related to global climate change. These studies include measurements of the isotopic composition of carbon dioxide (13CO2, CO18O) at a forest site, the isotopic composition of methane (13CH4 and CH3D) at a fen, the isotopic composition of nitrous oxide (N15NO, 15NNO and NN18O) after cryogenic pre-concentration and the measurement of carbonyl sulfide at a forest site.  I will also briefly mention the many other atmospheric species that can be quantified with these techniques including:  NH3, HNO3, HONO, NO, NO2, CO, HCHO, HCOOH, CH3CH3, CH2CH2 and many others.

报告人简介:David D. Nelson Jr.

Ph.D., Chemical Physics, Harvard University

Dr. Nelson is an expert in molecular spectroscopy, chemical kinetics and the detection of gas phase molecules. He is a co-developer of Aerodyne's quantum cascade laser trace gas monitors and author of the TDLWintel data acquisition and analysis software. His research interests include chemistry related to ozone depletion and global climate change, the study of regional air pollution, the use of isotopes as environmental tracers and the development of increasingly sensitive trace gas monitors. Dr. Nelson is a Fellow of the Optical Society of America.

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