LaseRitz: Far-infrared laser line assignment and prediction by the Ritz combination principle, with application to methanol and hydrazine

A "LaseRitz" program is described for the systematic assignment and predict ion of far-infrared laser (FIRL) transitions for a given molecule, such as methanol or hydrazine, which can be generated by optical pumping with known laser lines. The input data set for the program consists of identified mol ecular energy levels in ground and excited vibrational states, as compiled by our Ritz assignment program from the analysis of infrared (IR) bands and the FIR ground state spectrum. The program scans the data set for appropri ate IR matches with an input list of laser pump lines for CO2, N2O, etc., a nd generates an output table of all possible FIRL,lines consistent with the molecular selection rules and lying within a prescribed wavenumber range. Initial tests on CH3OH have led to three likely new FIRL assignments; for N 2H4, assignments have been found for 14 new FIRL transition systems and ver ified for five others. Lists have been produced (deposited as supplementary data with the JMS archive reached at www.idealibrary.com or available on r equest from the authors) of CH3OH and N2H4 FIRL lines potentially accessibl e by optical pumping with regular, sequence-band, hot-band, and isotopic CO 2 lines, plus N2O lines for N2H4. The systematic approach with the LaseRitz program is more global and rigorous than earlier line-by-line studies, per mitting calculation of all FIRL wavenumbers to spectroscopic accuracy. (C) 2000 Academic Press.