The shortest wavelength far-infrared laser line from CW CO2 laser pumped CH3OH and M-independent Stark splitting of laser lines

Methyl alcohol (CH3OH) molecules pumped with the 9R(16) CW CO2 laser line generate two new far-infrared laser lines at wavelengths of 33.4 and 36.4 mu m. The 33.4 mu m line has the shortest wavelength among the sub-mm lines reported so far from CH3OH and its isotopic species pumped with CW CO2 laser lines. Stark splitting is observed on the 36.4 mu m line as well as on the 39.9 and 77.4 mu m lines pumped with the 9P(34) and 9R(8) CO2 lines, respectively. It is pointed out on the 39.9 and 77.4 mu m lines that the Stark components in each of the Delta M=+or-1 sequences of the far-infrared transition are accidentally degenerate to give a frequency shift independent of the magnetic quantum number M.