Line profile of coherent radiation in separated fields due to the $F^{(2)}_2$ transition in methane

The theory of coherent radiation in separated fields (CRSF) is generalized to allow for the magnetic hyperfine line structure. An investigation is made of the frequency dependence of the CRSF intensity due to the $F^{(2)}_2$ transition in methane. The field shift of the central CRSF maximum is determined and the pressure dependence of the amplitude and half-width of the central CRSF maximum is obtained.