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Effects of crystal structure on the electrochemistry of boron-doped high temperature-high pressure (HTHP) diamond single crystals grown from a Ni-Fe-C melt are studied. On the {111}, {100}, and {311} faces, the linear and nonlinear electrochemical impedance measurements were performed and the rate of electron transfer for normalFefalse(CN)63­/4­ was evaluated. Like polycrystalline chemical vapor deposited films, the HTHP electrodes’ equivalent circuit includes a constant phase element. The uncompensated acceptor concentration in the semiconductor diamond was determined from Mott-Schottky plots and amplitude-demodulation measurements and was found to vary in the range of 1018 to 1021 cm−3. The difference in the electrochemical behavior of individual crystal faces is primarily attributed to different boron concentrations in the growth sectors associated with the faces. © 2002 The Electrochemical Society. All rights reserved.

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With a view toward laser isotope separation of Si, we have studied infrared multiphoton dissociation (IRMPD) of room temperature trichlorosilane, SiHCl 3 . Over the wavelength range investigated, multiphoton dissociation of the room temperature species exhibits a maximum efficiency at 12.6 µm and a threshold fluence of only ∼1 J/cm 2 . Vibrational overtone preexcitation of SiHCl 3 to the first SiH-stretch overtone (2ν 1 ) prior to IRMPD results in a 10-fold increase of the dissociation yield compared to molecules with only thermal excitation. In an effort to collect the nascent SiCl 2 dissociation fragments, we have tested a number of different molecules that could serve as a scavenger to convert them into a stable gaseous compound. Several of these molecules react directly with trichlorosilane after being decomposed by collisional energy transfer from vibrationally excited SiHCl 3 and therefore are not suitable for a laser isotope separation process. Of the compounds tested, we find that only BCl 3 scavenges SiCl 2 without significant reaction with the starting material.

Selective area electroless nickel and copper deposition onto the surface of diamond single crystals and polycrystalline diamond films has been realized. Three methods of laser-assisted activation of diamond surface were applied: (i) prenucleation of diamond surface with a thin layer of palladium catalyst via laser-induced decomposition of a palladium acetyl-acetonate [Pd(acac)2] solid film; (ii) deposition of palladium by means of the decomposition of Pd(acac)2 dissolved in dimethylformamide; (iii) laser-induced damage of diamond surface.