Abstract: The photoionization processes of dibromomethane have been investigated in the wavelength range 50～200 nm of synchrotron radiation.Based on the measured appearance potential(P_A) of the parent ion.the adiabatic ionization potential(P₁=10.23±0.01 eV) of the dibromomethane was obtained.Furtheremore,the dissociation energies(E_D),the formation enthalpies(E_F),the bond dissociation energies(E_BD)and the related thermochemical data of the species have been derived from the observed appearance potentials of the ionic fragments,Associating the obtained hats of formation with the previous thermochemical data,the most possible chnnels of dissociative photoionization have been analysed.

Key words: Photoionization, Photodissociation ionization, Appearance potential