Improved rovibrational constants and frequency tables for the normal laser bands of 12C16O2

New frequency difference measurements between Doppler-free stabilized laser lines in the 9.4- and 10.4-μm bands of ¹²C¹⁶O₂, including high-J and across-the-band-center measurements, have made significant improvements in the rovibrational constants. The absolute frequencies were referred to the methane stabilized 3.39-μm HeNe laser. Frequency tables generated from these constants have absolute uncertainties of less than two parts in 10¹⁰ and are about a factor of 10 better than older tables. In addition, the laser lines P_I(50) in ¹³C¹⁶O₂ and R_II(26) in ¹³C¹⁸O₂, which were used as reference lines in recent visible laser frequency measurements, were also measured to about the same accuracy.