ACCURATE ROTATIONAL CONSTANTS OF C12O216 FROM MEASUREMENT OF CW BEATS IN BULK GAAS BETWEEN CO2 VIBRATIONAL-ROTATIONAL LASER LINES

A room-temperature bulk GaAs mixer is used to mix frequencies of pairs of cw vibrational-rotational CO2 laser lines, each stabilized to line center. The beat frequencies, in the millimeter-wave region of 50-80 GHz, are measured for 37 pairs of transitions to better than 1 MHz. The deduced rotational constants for the relevant vibrational levels (00°1, 10°0, 02°0) are 25 to 200 times more accurate than the best previous results (from conventional spectroscopy). © 1969 The American Physical Society.