Department of Chemistry, McMaster University, Hamilton, Ontario, Canada L8S 4M1
Abstract:
Two-photon sequential absorption spectroscopy has been used to selectively excite rotational structure in the B---X absorption transition of the 129I2 molecule up to within 2 cm−1 of the dissociation limit. Vibrational and rotational constants have been obtained for the B state levels with υ = 71–79. Le Roy's equations for long-range behaviour are expressed in mass-reduced form, and it is shown that these equations can be successfully used to combine the spectroscopic constants for 127I2 and 129I2 to give improved values of the long range constants for the B state. The improved values are only slightly different from those previously obtained by the same technique for 127I2 alone.