摘要
Absolute frequencies of 23 transitions ranging from J = 2 to 70 for both the P and R branches of the 12 C 16 O 2 [10 0 1, 02 0 1] II ← 00 0 0 band near 2.7 μm are measured to 17 kHz accuracy with sub-Doppler saturated absorption spectroscopy using a precise single frequency PPLN (periodically poled lithium niobate) OPO (optical parametric oscillator). A refined set of molecular constants are obtained which gives the differences between measured and calculated values of less than 7 kHz.