PHOTOELECTRON IMAGING SPECTROSCOPY FOR (2-ENHANCED MULTIPHOTON IONIZATION OF ATOMIC IODINE PRODUCED FROM A-BAND PHOTOLYSIS OF CH3I(1) RESONANCE)

Photoelectron imaging spectroscopy has been applied to study on two-ph oton resonant third photon ionization of two states of atomic iodine ( 5p(5 2)P(3/2) and P-2(1/2)) in the wavelength region 277-313 nm. The t echnique has yielded simultaneously both relative branching ratios to the four levels of I+(P-3(2), P-3(0,1), D-1(2) and S-1(0)) with 5p(4) configuration and the angular distributions of outgoing photoelectrons , The product branching ratios reveal a strong propensity to populate particular levels in many cases, Several pathways have been documented for selective formation of I+(P-3(2)), I+ (P-3(0,1)) and I+(D-1(2)) i ons. In general, the final ion level distributions are dominated by th e preservation of the ion core configuration of resonant excited state defined by the J(c)l coupling scheme. Some deviations from this simpl e picture are discussed in terms of the configuration interaction of r esonant states and the autoionization in the continuum, The photoelect ron angular distributions are qualitatively similar, with a positive A (2) anisotropy coefficient of 1.0-2.0 and negligible A(4) in most case s, which suggests that higher-order Legendre terms are suppressed by t he restriction of a maximum orbital angular momentum of ejected electr on, 2. (C) 1997 American Institute of Physics.