Laser-induced phase transitions of carbon

Kudryashov, S. I.; Karabutov, Alexander A.; Kudryashova, M.A.; Beketov, V. I.; Зоров, Н. Б.

doi:10.1070/mc1998v008n01abeh000847

Cited by 2 publications

(2 citation statements)

References 3 publications

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“…Thus, it is considered that the swelled area of the reticulated structure might be graphitized to have carbon nanocrystals. Generally, in research on structural change of carbon thin films by laser, it is necessary to set the single pulse fluence of lasers to approximately 1 J/cm 2 and over, based on the thermal melting process [28,29]. Therefore, this work can be considered as a structural change by a mechanism different from the conventional one.…”

Section: Resultsmentioning

confidence: 99%

F2 Laser-Induced Micro-Reticulated Structural Changes of Amorphous Carbon Thin Films

Okoshi

2023

Micro

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Micro/nanoprocessing of materials using lasers is currently an active research topic. In that research, the choice of the laser to be used is critical, but the F2 laser, which has the shortest wavelength (157 nm) among commercially available lasers, has few research compared to its potential. In this paper, we discovered a new photochemical processing by using an F2 laser to irradiate an amorphous carbon thin film. The short wavelength and high photon energy of the F2 laser can photoexcite the surface of the thin film at high density and generate active oxygen atoms O(1D) by photodecomposition of atmospheric oxygen molecules. As a result, the optical change of the amorphous carbon thin film was induced without thickness reduction, and a micron-sized network-like, reticulated structural change was formed in the thin film surface after one month at the latest. The formed micron-sized reticulated structure was relatively swollen, and a graphitization occurred in the structure, observed by Raman spectroscopy. However, the structure was not observed when the laser irradiated area became smaller. This work has made it possible to form a micron-sized reticulated structure including carbon nanocrystals in an amorphous carbon, which is expected to further expand the applications of carbon materials.

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Section: Resultsmentioning

confidence: 99%

F2 Laser-Induced Micro-Reticulated Structural Changes of Amorphous Carbon Thin Films

Okoshi

2023

Micro

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“…This implies that the internal quasistatic vapour pressure in closed cavities of graphite foil exceeds by 2-3 times the value of the recoil pressure during the nonequilibrium hydrodynamic decomposition of the surface layer of the labile liquid phase in the PCG target and, hence, exceeds by 1-1.5 times the value of the equilibrium pressure of saturated carbon vapour at the same evaporation temperature, and corresponds to the formation of the supercritical state of carbon. Taking into account the calibration of the acoustic detector during laser evaporation of PCG, 6 the maximum pressure in the graphite foil target volume occupied by the substance in the supercritical state is 3400±500 bar at I 0 = = 2.5 GW cm -2 , which considerably exceeds the value of the critical carbon pressure (2210 bar 1 ).…”

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confidence: 99%