Absolute H atom density measurement in pure methane pulsed discharge

Absolute atomic hydrogen and methyl radical production resulting from direct electron impact dissociative excitation of CH4 has been measured in pulsed discharge by two-photon allowed laser induced fluorescence. For 20 Torr pure methane discharge with 480 ns pulse duration, 4-6 kV voltage applied, and 6-11.5 mJ input electrical energy yield of 10-22x10(15) cm(-3) hydrogen atoms, i.e., up to 4.5% dissociation of CH4 is achieved by direct electron impact with 50% energy conversion efficiency. (C) 2004 American Institute of Physics.