Knowledge Bank

One of the most powerful far-infrared lasers found today is the $CH3F$ $laser.1,2$ The operation of this laser is achieved through optical pumping of the transitions of the $\nu 3$ band of $CH3F$ by a $CO2$ laser operating at the 9.55 $\mu$ - P(20) $line.2,3$ The absorption coefficients of these transitions, which determine the optical pumping of the $CH3F$ laser, have not been thoroughly measured and can be calculated from the integrated intensity of the $\nu 3$ band, $Sb$. The value of $Sb$ was obtained from the measured value of $\alpha \nu$, the absorption profile of the transitions in this $\nu 3$ band, by the use of a semi-tunable $CO2$ laser operating at the 9.55 $\mu$ - p(20) line. The spectral shape of $\alpha \nu$ depends on three parameters: the mid-frequencies of these two transitions and $Sb$. Since the measured values of the mid-frequencies of the and transitions matched those found in the $literature,4$ the value of $Sb$ was, thus, accurately measured. The value obtained $Sb=619\pm 28cm-2atm-1$ is somewhat larger than that found in the $literature,5$ $484cm-2atm-1$. This result was confirmed by additional measurement of the average value of the absorption profile.