Optical emission spectroscopy has been employed to study the photolysis and the subsequent reaction processes of the mixture of Si2H6and C2H2irradiated with a 193 nm ArF excimer laser. The emission intensities of SiH*, Si*, and C2*were measured as a function of the laser energy up to 80 mJ (∼0.43 J/cm2). The formation processes of the radicals and atoms were estimated from the dependence of these intensities on the laser energy. The dependence of the SiH* intensity in the low‐energy region up to 10 mJ was quadratic and revealed two‐step processes. The dependence of the intensities of Si* and C2*was the 1.3–1.6 power of the laser energy, which revealed the saturation of the processes. The intensity of C2*increased when Si2H6was added to C2H2. The origin of this increase is the production of the carbon‐based radicals by the collisions of Si* with C2H2and C2H. ©1995 American Institute of Physics.