Diamond films were successfully synthesized in both parallel-plate radio frequency (rf: 13.56 MHz)CH4andCH3OHplasmas with injection of H and OH radicals generated in the remote microwave (2.45 GHz)H2/H2Oplasma. Effects of H, OH, andCH3radicals on the diamond film formation in the rf plasma reactor were investigated by the formation of diamond films employing radical injection technique and the measurement of density in the plasma. Under the condition of diamond film formation,CH3density was measured by infrared diode laser absorption spectroscopy (IRLAS). The kinetics ofCH3in rfCH4andCH3OHplasmas with injection of H and OH radicals were evaluated from the results of optical emission spectroscopy and lifetime ofCH3radicals estimated by IRLAS. ©1997 American Institute of Physics.