Two obvious ionization peaks, which were not observed in previous synchrotron radiation photoelectron spectroscopy, have been observed in binding energy spectra of dichlorodifluoromethane in the range from 24 eV to 30 eV using (e, 2e) electron momentum spectroscopy. Ionization potentials of these two transitions are determined and experimental momentum profiles for corresponding orbitals have been obtained. By comparing experimental momentum profiles with the calculated ones, the two peaks are clearly assigned to ionization from 2a(1), and 1b(2), inner valence orbitals. Furthermore, the pole strengths of these transitions are also determined by fitting calculated momentum profiles to measured ones. (c) 2006 Elsevier B.V. All rights reserved.