Laser microprobe and resonant laser ablation for depth profile measurements of hydrogen isotope atoms contained in graphite

We measured the depth profile of hydrogen atoms in graphite by laser microp robing combined with resonant laser ablation. Deuterium-implanted graphite was employed for the measurements. The sample was ablated by a tunable lase r with a wavelength corresponding to the resonant wavelength of 1S-2S of de uterium with two-photon excitation. The ablated deuterium was ionized by a 2 + 1 resonant ionization process. The ions were analyzed by a time-of-flig ht mass spectrometer. The deuterium ions were detected clearly with the res onant ablation. The detection limit was estimated to be less than 10(16) at oms/cm(3) in our experiments. We determined the depth profile by considerin g the etching profile and the etching rate. The depth profile agreed well w ith Monte Carlo simulations to within a precision of 23 mum for the center position and 4-mum precision for distributions for three different implanta tion depths. (C) 2001 Optical Society of America.