Photo Double-Ionization of Deuterium Chloride Studied by Threshold Photo- electrons Coincidence Spectroscopy G.C. King(1), A.J. Yencha(2), M.C.A. Lopes(1,3), J.D. Bozek(4), N. Berrah(5) (1) Manchester University (2) University at Albany (3) Univeridade Federal de Juiz de Fora (4) Lawrence Berkeley National Laboratory (5) Western Michigan University Photo double-ionization (PDI) of DCl has been investigated in the 35-38 eV energy range using synchrotron radiation on beamline 10.0.1.2 of the Advanced Light Source (ALS) by the threshold photoelectrons coincidence (TPEsCO) method. The TPEsCO spectrum of DCl, encompassing the formation of the ground (X 3sigma-) and first-excited (a 1delta) states of DCl++, was recorded at good resolution (about 13 meV) using a pair of penetrating-field electron spectrometers. Resonance autoionization of satellite-ion Rydberg states appear to play a major role in the formation of these doubly-charged electronic ion states.