Measurement of stable isotopes of atmospheric H2 and its application to atmospheric photochemistry

Abstract

We developed a method to analyze stable isotope ratio of atmospheric H2.The method requires only ~300 ml of air, is operated in an on-line system, and yields values within 2 per mil of precision, which is better than that obtained by conventional off-line method with ~ 4000 l of air. However, because of different peak shapes of reference and sample air, it needs to calibrate the analytical system in a regular manner. We used the system to determine kinetic isotope effects occurring during the photolysis of formaldehyde in the atmosphere. In the presentation we will discuss in detail determination of kinetic isotope effects under the ambient conditions for the photolysis of formaldehyde.