Relaxation of the nd → (n + 1)p Resonances in Atomic Bromine and lodine

Abstract

Iodine and bromine atoms, respectively produced by laser-induced photo-dissociation of I2 and Br2, have been photoexcited in the region of the 4d (I) and 3d (Br) shell excitation. Strong resonances are observed in the absorption spectrum and are assigned to nd → (n+1)p(2D5/2) transitions. Photoelectra spectra reveal that the main decay of such excited states is autoionization into outer-shells, especially into the singlet states. A modified Fano theory for partial cross sections has been applied to the special case of nearly Lorentzian photoemission profiles in atomic iodine. The decay into the 5p-1 and 5s-1 channels amounts to about 65% of the total decay rate. Moreover, by photoin spectroscopy, we have measured the I2+/I+ ratio on the resonance, very close to the one measured off the resonance. These results are very different from those obtained in the study of the decay of core-to-Rydberg nd9n'p resonances in rare gases. On the other hand, strong (n + 1)s-1 satellites have been observed. It appears, that most of these satellites are due to a strong interaction in the final state between the parent (n + 1)s(n + 1)p5(1P) configuration and (n + 1)s2(n + 1)p3(n + 1)d(1P) satellites configurations.