The project concerns the development and use of laser diagnostics to study the kinetic of radicals in CH4, SiH4, NH3, H2 glow discharges. First, laser-induced fluorescence will be used to detect SiH and CH radicals in realistic conditions of Si and C film depositions. The results will be normalized with previously obtained mass spectrometry radical measurements. Second, a new laser system based on diode-laser injection-seeded optical parametric oscillator will be developed to detect hydrogen atoms using two-photon absorption laser-induced fluorescence. This diagnostic will be used to determined the H atom concentration profiles in the plasma. The influence of the nature of the substrate on the atom concentration will lead to the determination of surface loss probabilities. These measurements will complement the results previously obtained using other diagnostic techniques like optical emission, masse spectrometry and coherent anti-Stokes Raman scattering. Finally, experimental data will be used to interactively validate numerical models currently developed in the laboratory.