High resolution spectroscopy of 13CH 3OH around the 10R(20) CO 2 laser emission: New FIR laser lines, frequency measurements and assignments

Abstract

We investigated the IR absorption spectrum of 13CH 3OH around the frequency of the 10R(20) CO 2 laser line. We found two absorption lines which can be excited by 10R(20) and studied the FIR laser emissions excited by this pump line using a waveguide CO 2 laser of 300 MHz tunability. We report two new FIR laser lines of large offset, not previously observed due to their weakness and closeness to other stronger lines. We measured the frequencies of five FIR laser lines for the first time by an accurate heterodyne technique and present the complete assignments of the IR-FIR laser systems relative to this pump line. Furthermore we present new frequency values for two FIR laser lines whose frequencies had been previously wrongly measured.