A. Van Lerberghe

Absolute frequency determination of super-narrow CO2 saturation peaks observed in an external absorption cell

Abstract We have succeeded in observing very narrow saturation resonances (hwhm=2.1 kHz) of room temperature CO2 by monitoring directly the absorption of a CO2 laser beam in an external absorption cell. Through successive recordings of the CO2 lines and OsO4 lines of known absolute frequency, we have been able to perform a preliminary determination of the frequencies of three CO2 lines (respectively P(14) and R(10) of the 10.4 μm band) with an accuracy of the order of one kilohertz. A good agreement is found with previous measurements based on the saturated 4.3 μm fluorescence method. The main interest of this new method is to provide values for the frequencies in the free-flight regime.

Self pulsing in a CO2 ring laser with an injected signal

Abstract The dynamic behavior of a cw CO2 ring laser with injected signal is analyzed in a preliminary experiment as a function of detuning and injection amplitude. It is shown that for constant injected intensity, self pulsations occur in the neighbourhood of the locking edge. Two distinct characteristic frequencies, associated with self pulsation and relaxation, govern the complex dynamic evolution of the system as the locking edge detuning is approached.

High Resolution Saturation Spectroscopy with CO2 Lasers. Application to the v3 Bands of SF6 and OsO4

Saturation spectroscopy of vibration-rotation transitions started in 1967 with the first observations of molecular Lamb dips in H2O and CO2 lasers [1, 2]. One year later the inverted Lamb dip technique of LEE and SKOLNICK was beautifully applied to a vibration-rotation line of CH4 by J.L. HALL and R. BARGER [3]. With the large output power available from CO2 lasers it appeared very quickly that the absorbing gas could be removed outside the laser resonator with a much greater flexibility in the experiments. For example it became possible to use the saturation chopper method in which only the signal corresponding to the non-linear resonances was amplified and recorded [4]. Many spectra corresponding to numerous molecules were obtained by this technique but most experiments used SF6 as the absorbing gas.

Internal Dynamics of Simple Molecules Revealed by the Superfine and Hyperfine Structures of Their Infrared Spectra

This paper reports some of the progress achieved with our 10 µm saturation spectrometer since our 1979 FICOLS presentation [1] with a special emphasis on recent results in molecular physics.