In this RUI project in the Experimental Physical Chemistry Program of the Chemistry Division, Judge will study the gas phase absorption spectra of small polyatomics, such as selenoformaldehyde (CH2Se) and thioformyl fluoride (HFCS), by a combination of classical and modern techniques. The theory of a rotational Hamiltonian suited to the specific type of angular momenta experienced by these molecules will be developed. In particular, a computer program for band-contour analysis using this Hamiltonian will be augmented for use on a microcomputer. Such a program will be of use to other spectroscopists in the field. Judge and his students will do research at their own institution during the academic year and will continue to work in the summers in the labs of Clouthier (University of Kentucky) and Moule (Brock University, Ontario). %%% In this research project Prof. Judge will use a mixture of conventional spectroscopy and laser methods to derive data about small molecules which are representative of chemically important groups related to formaldehyde. These two complementary methods yield well-determined spectroscopic constants for these molecules. The results of these spectroscopic analyses will be of interest to both experimental and theoretical chemists as well as to astrophysicists.