Optical spectrometric analysis of stable isotopes and the application of this method of analysis

Describes the use of non-radioactive isotopes of H, C, N, O, S as indicators or tracers in chemical and biological processes. The isotopes are measured by way of an optical spectrometric method, involving the observation of electromagnetic radiation absorbed or emitted during changes in energy states. The usual procedure for 15N is emission spectroscopy of gas samples. The theory is explained in some detail. A method is described which enables 13C and 14C to be measured. Microwaves are applied to the gas sample (CO2) at suitable conditions. The isotope atom percentage is found by measuring the spectrum peaks. (J.S.)