Communication: First observation of ground state I(2P3/2) atoms from the CH3I photodissociation in the B-band

Abstract

The photodissociation of CH3I in the second absorption band (the B-band) has been studied at the wavelength 199.11 nm, coincident with the 31 0 3R1(E) ← X˜ (1A1) CH3I vibronic transition, using a combination of slice imaging and resonance enhanced multiphoton ionization detection of the CH3 fragment. The kinetic energy and angular distributions of the recoiling CH3 fragment confirm a major predissociation dynamics channel as a result of the interaction between the bound 3R1 Rydberg state and the repulsive 3A1(E) state − ascribed to the A-band − yielding CH3 fragments in correlation with spin-orbit excited I*(2P1/2) atoms. In addition, first evidence of a non-negligible population of ground state I(2P3/2) atoms in the CH3 fragment slice images, suggests a secondary predissociation mechanism via interaction between the 3R1 Rydberg state and the repulsive A-band 1Q1 state.