Knowledge Bank

The difference band $\nu 1-\nu 3$ of $CF3\mathrm{<mrow\; data-mjx-texclass="ORD">35</mrow>}Cl$ located near $631cm-1$ has been investigated few years ago by means of Fourier transform infrared spectroscopy /1/. Because of the limited resolution achieved it has not been possible to resolve the K structure of the P(J) and R(J) multiplets. Subsequently the $\nu 1$ band has been investigated with a diode laser spectrometer, which allowed a precise evaluation of the molecular parameters /2/. As a part of a continuing effort to investigate the molecular structure of the trifluorochloromethane we measured at a diode laser resolution the $\nu 1-\nu 3$ band in the 622 to $641cm-1$ region. The K structure of many P(J) and R(J) manifolds has been resolved and positively identified. The rotational analysis has been extended in the P and R branches up to $J=39$ and 47 respectively and more than 650 lines have been assigned. A least-squares fit of the observed transitions to the energy expression including the quartic centrifugal distortion terms was performed and molecular constants for the $\nu 1-\nu 3$ difference band were determined. From the obtained parameters the vibrational rotational constants of the $\nu 3$ fundamental were derived. Spectra, details of the interpretation and results from the analysis will be presented.