ZERO KINETIC-ENERGY PHOTOELECTRON-SPECTROSCOPY OF RYDBERG EXCITED MOLECULAR-IODINE

Two color (2+1') zero kinetic energy pulsed field ionization (ZEKE-PFI) spectra of I2 ionized via a number of gerade Rydberg excited states have been recorded for the first time. Ionization into both X 2Π3/2,g and X2Π1/2,g spin-orbit ionic substates was achieved by selective excitation of Rydberg states having the appropriate spin-orbit ionic core. Adiabatic ionization energies have been determined as 75 069±2 cm-1 for the X 2Π 3/2g state and 80 266±2 cm-1 for the X2Π1/2g state with ωe values for the two states determined as 240 ±1 and 229 ±1 cm-1, respectively. The ZEKE-PFI spectra recorded for the lower spin-orbit state exhibit non-Franck-Condon behavior which has been interpreted in terms of an autoionization mechanism. The ZEKE-PFI technique has also been used to probe the extent of Rydberg and ion-pair character in a strongly mixed Rydberg/ ion-pair state. © 1995 American Institute of Physics.