Heterodyne frequency measurements and analysis of CO2 laser hot band transitions

Abstract New frequency measurements of molecular lines in the P branch of the 01 1 1-[11 1 0, 03 1 0] I band of 12 C 16 O 2 , observed in laser emission, and lines in the R branch, observed in absorption with a tunable-diode laser, have been made by heterodyne difference frequency techniques, with stabilized CO 2 lasers generating the reference frequencies. The data obtained, plus additional results of measurements made by two other groups of researchers, were combined in a leastsquares fit to obtain improved rovibrational constants for this band. The new constants predict more reliably the frequencies of both the P - and R -branch transitions. A table of transition frequencies and their estimated uncertainties is given for this band.