Long range behavior of the gerade states near the 2P3/2+ 2P3/2 iodine dissociation limit by laser‐induced‐fluorescence Fourier‐transform spectroscopy

The near infrared LIF–FTS spectra from the I2 B 0u+ state, excited by an argon ion laser and recorded by a high resolution Fourier‐transform spectrometer, contain information about perturbations between the gerade states converging to the I2→2I(2P3/2) dissociation limit. The observed perturbation interactions are sampled at internuclear distances near 5 A and are interpreted in a separated atom (I2=Ia+Ib; ψI2=φaφb; φa=‖ ja=3/2, ma〉) basis set. Near r=5 A the X 0g+ and a′ 0g+ states are found to have predominant ma=−mb=±1/2 and ma=−mb=±3/2 character, respectively, but with slight ‖m‖=1/2∼‖m‖=3/2 mixing. In this pure ‖m‖ basis, S=sa+sb and Jatomic=ja+jb are not well defined, but in the limit of complete ‖m‖=1/2∼‖m‖= 3/2 mixing, S and Jatomic are well defined. The behavior of three gerade states (X 0g+, a′ 0g+, a 1g) at large internuclear distance has been analyzed using the long range theory of LeRoy and Bernstein. The results are in fair agreement with theoretical predictions, and give a direct and precise...