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Sublimation (phase transition)

About: Sublimation (phase transition) is a research topic. Over the lifetime, 8201 publications have been published within this topic receiving 126273 citations.


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Journal ArticleDOI
TL;DR: In this paper, the authors showed that the SiC(0001¯) (C-terminated) surface of a semiconductor can have structural domain sizes more than three times larger than those on the Si face while reducing substrate disorder from sublimation by an order of magnitude.
Abstract: With expanding interest in graphene-based electronics, it is crucial that high quality graphene films be grown. Sublimation of Si from the 4H-SiC(0001) (Si-terminated) surface in ultrahigh vacuum is a demonstrated method to produce epitaxial graphene sheets on a semiconductor. In this letter the authors show that graphene grown from the SiC(0001¯) (C-terminated) surface are of higher quality than those previously grown on SiC(0001). Graphene grown on the C face can have structural domain sizes more than three times larger than those grown on the Si face while at the same time reducing SiC substrate disorder from sublimation by an order of magnitude.

335 citations

Journal ArticleDOI
TL;DR: In this paper, the authors show that carbon nanostructures such as singlewalled and multi-walled nanotubes (SWNTs and MWNTs) or graphitic polyhedral nanoparticles can be produced using various methods, such as electric arc discharge process, the laser ablation method, or the solar tech- nique.
Abstract: Carbon nanostructures such as single-walled and multi-walled nanotubes (SWNTs and MWNTs) or graphitic polyhedral nanoparticles can be produced using various methods. Most of them are based on the sublimation of carbon under an inert atmosphere, such as the electric arc discharge process, the laser ablation method, or the solar tech- nique. But chemical methods can also be used to synthesize these kinds of carbon materials: the catalytic decomposi- tion of hydrocarbons, the production by electrolysis, the heat treatment of a polymer, the low temperature solid pyrolysis, or the in situ catalysis.

323 citations

Journal ArticleDOI
TL;DR: In this paper, a set of energy functions of internal coordinates and interatomic distances is used for calculating simultaneously and consistently many properties of alkanes, including unitcell parameters; heat of sublimation; molecular and lattice vibrations; thermal expansion of the unit cell.
Abstract: A set of energy functions of internal coordinates and interatomic distances is used for calculating simultaneously and consistently many properties of alkanes. Comparison between calculated and experimental data is used as a means for systematically selecting energy functions and determining their parameters. Properties calculated are: unit‐cell parameters; heat of sublimation; molecular and lattice vibrations; thermal expansion of the unit cell—all these for n‐hexane and n‐octane crystals. Enthalpy differences—for gauche–trans butane and for axial–equatorial methyl‐cyclohexane. Excess enthalpies for the series cyclopentane through cyclodedcane and molecular conformations and vibrations for a selected number of cyclo‐ and n‐alkanes molecules. Some of the results and conclusions from these calculations are: molecular vibrations in the crystal are in part higher than in the gas, and the corresponding enthalpy difference contributes to the heat of sublimation equally as much as the lattice vibrations. Anharmonicity of lattice and molecular vibrations contributes significantly to the calculated unit‐cell parameters of crystals of n‐hexane and n‐octane at 0°K; thermal expansion is largest in the a1 direction. The Lennard‐Jones and Coulomb (12–6–1) potential is inadequate to account simultaneously for intra‐ and intermolecular interactions; the 9–6–1 potential and the exp‐6–1 potential are equally preferable. The intermolecular interactions exihibit an anisotropy not fully represented by functions of interatomic distances; anisotropy is the source of systematic discrepancies between the calculated and measured unit‐cell dimensions.

321 citations

Journal ArticleDOI
TL;DR: New experimental results concerning molecular interactions between the nitrogen bases of nucleic acids in the crystalline phase and in vacuo are reported and the energy gain in the formation of trimers of identical molecules was shown to be larger than that for dimers.
Abstract: New experimental results concerning molecular interactions between the nitrogen bases of nucleic acids in the crystalline phase and in vacuo are reported. The temperature dependence of the evaporation rate is measured for solid species. The sensitivity of conventional methods of sublimation heat measurements was improved essentially using a quartz resonator serving as a precise sensor of evaporation rate. Sublimation heats were found for both canonical bases and a number of their derivatives. The in vacuo formation of base associates interacting through hydrogen bonds was observed with a field mass spectrometer. The dimer formation enthalpies, which are indicative of a stronger attraction in complementary pairs compared with noncomplementary ones, were derived from the temperature dependence of ionic currents. Hydrogen-bound complexes of more intricate associates (base trimers and aqueous molecules associates) were studied. The energy gain in the formation of trimers of identical molecules was shown to be larger (per base molecule) than that for dimers.

319 citations

Journal ArticleDOI
TL;DR: In this article, a technique to produce samples consisting primarily of C60 and C70 by fractional sublimation of carbon soot was found and used to produce solid films of these molecules.

314 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20227
2021193
2020235
2019221
2018240
2017265