A Cavity Search Spectrometer for Free Radical Microwave Rotational Absorption Studies

Abstract

A Zeeman modulated microwave spectrometer, specifically designed for K band rotational studies of gaseous free radicals and transient molecular species and using a Fabry‐Perot type resonator as the absorption cell, is described. The theoretical sensitivity of the system is shown to be comparable to that of the most sensitive waveguide cell spectrometers. The previously assigned spectra of OH and NO₂ radicals have been successfully located with the system. The utility of the system as a search spectrometer for free radicals has been substantiated by locating previously unreported spectra for the NO₂ molecule and NF₂ (difluoroamino) free radical.