ASPECTS OF DIODE LASER SPECTROSCOPY AT 14-15 $\mu$m

Author Institution: Department of Physics, The Ohio State UniversityA tunable diode laser has been used as a source of infrared radiation with a two-meter focal length vacuum infrared spectrometer equipped with a 31 grooves per mm echelle grating. Since this instrument was used previously for recording infrared spectra, it has already been equipped with a precision grating drive; the scanning features of this grating were very useful indeed in tracking the laser modes. Also, the exact location of the spectral region being scanned was easily identified in view of the available information about the grating settings. Use of a Fabry-Perot etalon with an air spacing has facilitated the simultaneous observation of fringes about $0.0165\;cm^{-1}$ apart and therefore accurate determination of spectral positions was possible commensurate with the spectral resolution achieved which was about $0.002\;cm^{-1}$ in the region $14-15\;\mu $m. Spectra of $HCN, CO_{2}, C_{2}H_{2}$ and $O_{3}$ occurring in this region have so far been recorded. Their interpretation and molecular parameters obtained will be the basis of the results to be presented