Structural properties of amorphous hydrogenated carbon. I. A high-resolution neutron-diffraction study

Abstract

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Atomistic modeling of hydrocarbon systems using analytic bond-order potentials

“…Other smaller peaks between 1.7 and 2.2 Å belong to correlations in the second coordination shell associated with H-C-H and C-C-H bonds. These small features are in a good agreement with experimental observations [54]. Fig.…”

Structure of a-C:N:H prepared from ammonia

“…For both samples, the combined CC and CN first neighbor peak is at 1.43 Å, which is shorter than that obtained for CC nearest neighbors in a-C:H samples. 31,33 This is due to the presence of CN and NN bonds, which are shorter than the expected C-C and C‫ס‬C bonds, and therefore the average network neighbor bond distance observed for these a-C:N:H samples, where the correlation peaks overlap, appears shorter. The CH and NH correlations are observed as a dip in the data at ∼1 Å.…”

“…Building on our work on a-C:H 31,32 and earlier studies on a-C:N:H, 33,34 we present complementary neutron diffraction, inelastic neutron scattering and infrared spectroscopy data for a-C:N:H samples, with compositions of 3 and 7 at.% nitrogen, which will be used to provide additional insight into the carbon, nitrogen, and hydrogen bonding environments present. In particular, we examine the effects of nitrogen incorporation on the atomic-scale structure of the material with reference to the use of ammonia, NH 3 , as the source of nitrogen, and a supplementary source of hydrogen, in the precursor gas.…”

“…31, 37, and 38) and in particular the pulsed neutron source ISIS at the Rutherford Appleton Laboratory (Didcot, UK) allows one to obtain high-resolution real-space data, to the extent that it is possible to distinguish sp 1 , sp 2 , and sp 3 carbon-bonding environments directly. 31 Furthermore, because the neutron, unlike x-rays or electrons, scatters from the nucleus, there is no atomic-number-dependent form factor, and the correlations involving hydrogen are also accessible.…”

Computational materials synthesis. III. Synthesis of hydrogenated amorphous carbon from molecular precursors

“…From electronic structure calculations it has been suggested that the structure of a-C:H is composed of graphitic clusters of fused rings in an sp 3 matrix 5,6 and some experimental observations have tended to support this idea. [7][8][9][10][11][12][13][14] However this view has been challenged in a recent series of papers, [15][16][17][18] whose authors interpret their results to mean that the sp 2 bonds are olefinic ͓olefinic, hydrocarbon containing a carbon-carbon double bond, the bond is localized; aromatic (benzoic), hydrocarbon containing a phenyl ring, the bonds are delocalized around the ring; graphitic, graphitelike structure, the bonds are delocalized over an area͔ and not graphitic or benzoic. An earlier work also found localization of electrons.…”