The laser induced fluorescence spectra of the C–X transitions of HgRg (Rg=Ne, Ar, Kr, and Xe) van der Waals complexes formed in a supersonic jet have been observed in the longer wavelength side of the Hg(1P1−1S0) resonance transition by use of a tunable vacuum ultraviolet laser, which is generated by the two-photon resonant four-wave sum mixing in Sr vapor. On the basis of vibrational quantum numbers assigned to the upper levels of the observed C–X transitions,potential parameters of the C state are determined. The interatomic potentials for the C state are well approximated by a Morse function and the dissociation energies for HgNe, HgAr, HgKr, and HgXe are 89, 486, 1410, and 3463 cm−1 , respectively.