Hydrogenated Nanoporous Diamond Films

Abstract

Nanoporous diamond films up to 20 µ m thick with a pore size of 1-1.5 nm and porosities from 0.4 to 0.6 are produced by selective etching in air. The effect of hydrogen plasma processing on the IR absorption and electron paramagnetic resonance spectra of the films is investigated. The results indicate that the concentration of bonded hydrogen in the hydrogenated nanoporous diamond films attains 20 at %. The kinetics of hydrogen desorption are studied as a function of temperature.

Infrared absorption spectra of coals with different degrees of coalification

“…2a) due to stretching vibrations (symmetric and antisymmetric) of aliphatic CH 2 groups. The spectral position and half-width of the absorption bands for the stretching vibrations of unassociated CH groups in the coals are similar on the whole to those appearing in the IR spectra of solids such as nanoporous diamond samples [17]. The intensity is low for the bands with maximum near 2940 and 2880 cm -1 (aliphatic CH 3 groups) and in the shorter wavelength region (2970-3080 cm -1 : hydrogen associated with aromatic carbon [18]) in the spectra of the studied carbons.…”

Optical spectroscopy of the surface of nanoporous diamond films

“…As in [26], in making nanoporous diamond film, the UNC diamond film thickness decreased during annealing by no more than 0.05 μm (<6%). Some time after etching in H 2 SO 4 + K 2 Cr 2 O 7 solution and/or annealing in air at T ≥ 450 o C, the band for the stretching vibrations of the CH x groups in the IR spectra of oxidized UNC diamond films was appreciably higher in intensity than in the spectra of the original samples (as in nanoporous diamond films [26]). This in particular also stimulated investigation of the behavior of different functional groups in nanoporous UNC diamond films.…”

“…Such a structural transition was accompanied by changes in the IR spectra [19,24]. IR spectroscopy is an effective method for studying the microstructure of surface functional groups, especially for nanosized and nanoporous materials [25,26] having high surface area to volume ratio. The characteristic features of the state of the surface for diamond materials and its functionalization to date have been studied mainly using nanodiamond powders obtained by detonation synthesis.…”

“…The band for the stretching vibrations of the CH x groups consists of five individual lines with half-widths in the range 15-30 cm are typical of nanoporous diamond films [26] and nanosized diamond particles [30]. According to [31], CH 2 and CH 3 groups are characteristic respectively for the (100) and (111) faces of diamond.…”

“…According to [31], CH 2 and CH 3 groups are characteristic respectively for the (100) and (111) faces of diamond. Furthermore, the presence in the IR spectra of intense bands corresponding to vibrations of sp 3 bonds of CH 3 groups suggests that on the surface of porous UNC diamond (as in nanoporous undoped diamond films [26]), there are many steps and solitary atoms of carbon. Absorption bands in the 3000-3100 cm -1 region, characteristic for vibrations of sp 2 bonds of CH x groups, were missing in the UNC diamond spectra, since the major fraction of sp 2 carbon was removed by oxidation from the surface of the studied films.…”