Photo-double ionization of deuterium chloride studied by threshold photoelectrons coincidence spectroscopy

Photo-double ionization of DCl has been investigated in the 35.5-38 eV ener gy range using synchrotron radiation on beamline 10.0.1.2 of the Advanced L ight Source by the threshold photoelectrons coincidence (TPEsCO) method. Th e TPEsCO spectrum of DCl, encompassing the formation of the ground (X (3)Si gma(-)) and first-excited (a (1)Delta) states of DCl2+, was recorded at goo d resolution (similar to 13 meV) using a pair of penetrating-field electron spectrometers. Four vibrational bands were identified in both electronic-s tate systems. In addition, the threshold photoelectron (TPE) spectrum of DC l for the formation of singly-charged DCl was recorded simultaneously in th e same energy range. Indirect resonance autoionization of Rydberg ion state s appears to play a substantial role in the formation of the (X (3)Sigma(-) ) State of DCl2+ while the (a (1)Delta) state appears to be formed primaril y by direct photo-double ionization. (C) 1999 Elsevier Science B.V. All rig hts reserved.