Carbon nitride thin films prepared by radio frequency reactive sputtering of graphite in pure nitrogen plasma have been characterized by x-ray photoelectron spectroscopy (XPS) for probing the chemical bonding in the films. The multiple binding energy values obtained for the C 1s and N 1s photoelectrons in the film suggest that both the C and N atoms exhibit at least three types of chemical states, manifestative of different types of the C-N bonding present in the material. The presence of theoretically predicted beta-C3N4 phase in our C-N films has been suggested on the basis of XPS and optical data.