The gas-phase chemiluminescence spectra of chlorine atom recombination reactions in argon with pressures up to 170 bar were recorded by the laser photolysis/chemiluminescence detection scheme. With the spectroscopic data available in the literature and the monochromator functions determined experimentally and by assuming that the pressure line broadenings and frequency shifts follow the conventional Lorentzian form, for the first time the chemiluminescence spectra were quantitatively decomposed into the emissions of the B (3) Pi(0(u)(+)) --> X (1) Sigma(g)(+) and A (3) Pi(1(u)) --> X (1) Sigma(g)(+) transitions. The relative luminescence weights of these two emission electronic states, the vibrational temperatures, the pressure line broadenings, and frequency shifts were obtained. Their implications on the mechanisms of the chlorine atom recombination reactions and the interaction strength between the chlorine molecule and argon atom were discussed.