Diamond-like bonds in amorphous hydrogenated carbon films induced by x-ray irradiation

Sato, Fumio; Saito, Nobuo; Hirano, Yoshiyuki; Jayatissa, Ahalapitiya H.; Takizawa, Kenji; Kawado, Seiji; Kato, Takanori; Sugiyama, Hiroshi; Kagoshima, Yasushi; Ando, Masami

doi:10.1116/1.581380

Cited by 11 publications

(10 citation statements)

References 17 publications

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“…Another intriguing feature of carbon materials is that, due to the high flexibility of the carbon bonding, the connectivity of carbon atoms is quite changeable by exotic means. Particularly, signatures for the presence of electronic excitation 0039 effects have been accumulated in recent years [1][2][3][4][5][6][7][8][9][10][11][12]. Experimentally, Ma et al [1] conducted X-ray absorption and emission experiments on diamond crystals with results suggesting that the excitation of 1s core electrons induces a short-lived displacement of carbon atoms from the lattice sites.…”

Section: Introductionmentioning

confidence: 97%

Evolution kinetics of sp2 ordering in tetrahedral amorphous carbon films induced by electron irradiation

et al. 2005

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Section: Introductionmentioning

confidence: 97%

Evolution kinetics of sp2 ordering in tetrahedral amorphous carbon films induced by electron irradiation

et al. 2005

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“…The origin of the atomic motion is suggested to be an effect of surface diffusion, which is different from desorption caused by core-excitation. 2 This is because the number of atoms does not change (i.e., does not decrease) after X-ray irradiation, as interpreted by comparison between Figures 1(c and f).…”

Section: Resultsmentioning

confidence: 94%

“…Although the atomic motion can not be attributed to atomic desorption but to diffusion because of the stable number of the surface atoms, atomic diffusion can be produced either by a thermal effect or by the core-excitation effect followed by the cascade Auger relaxation processes. 2 Thus, the track images for X-ray irradiation of the energies across the Ge K-absorption edge (11.103 KeV) were compared. Figure 4 shows the track images on a common Ge(111) surface taken for the different incident photon energies ((a) 11.089 KeV, (b) 11.119 KeV, photon density = 2 4 × 10 15 photons/s/mm 2 , irradiation time = 5 min for both).…”

Section: Dependence On the Incident Photon Energymentioning

confidence: 99%

“…most outstandingly different from conventional photoinduced processes by visible laser, is that photons can excite specific inner-shell electrons of atoms. 2 Thus, elementselective treatment is possible using the energy of X-rays tunable to an absorption coefficient dependent on the material. On the other hand, a negative example is the damage on a sample that limits the resolution of structural studies.…”

Section: Introductionmentioning

confidence: 99%

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Direct Observation of X-ray Induced Atomic Motion Using Scanning Tunneling Microscope Combined with Synchrotron Radiation

Saitô¹,

Tanaka²,

Takagi³

et al. 2011

J. Nanosci. Nanotech.

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X-ray induced atomic motion on a Ge(111)-c(2 x 8) clean surface at room temperature was directly observed with atomic resolution using a synchrotron radiation (SR)-based scanning tunneling microscope (STM) system under ultra high vacuum condition. The atomic motion was visualized as a tracking image by developing a method to merge the STM images before and after X-ray irradiation. Using the tracking image, the atomic mobility was found to be strongly affected by defects on the surface, but was not dependent on the incident X-ray energy, although it was clearly dependent on the photon density. The atomic motion can be attributed to surface diffusion, which might not be due to core-excitation accompanied with electronic transition, but a thermal effect by X-ray irradiation. The crystal surface structure was possible to break even at a lower photon density than the conventionally known barrier. These results can alert X-ray studies in the near future about sample damage during measurements, while suggesting the possibility of new applications. Also the obtained results show a new availability of the in-situ SR-STM system.

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“…The lack of an observed change in the sp 3 /sp 2 ratio is in contrast with the results of irradiating such materials with certain X-rays. 25,26 Irradiation of hydrogenated a-C by ~10 keV synchrotron radiation 25 results in an increase in the sp 3 fraction. Contrary to that, sp 3 -to-sp 2 conversion occurs in tetrahedral a-C (ta-C) irradiated at the carbon K-edge (the 1s threshold at 280-300 eV).…”

Section: Resultsmentioning

confidence: 99%

Radiation damage to amorphous carbon thin films irradiated by multiple 46.9 nm laser shots below the single-shot damage threshold

Juha

Hájková

Chalupský

et al. 2009

Journal of Applied Physics

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High-surface-quality amorphous carbon (a-C) optical coatings with a thickness of 45 nm, deposited by magnetron sputtering on a silicon substrate, were irradiated by the focused beam of capillary-discharge Ne-like Ar XUV laser (CDL = capillary-discharge laser; XUV = extreme ultraviolet, i.e., wavelengths below 100 nm). The laser wavelength and pulse duration were 46.9 nm and 1.7 ns, respectively. The laser beam was focused onto the sample surface by a spherical Sc/Si multilayer mirror with a total reflectivity of about 30%. The laser pulse energy was varied from 0.4 µJ to 40 µJ on the sample surface. The irradiation was carried out at five fluence levels between 0.1 J/cm 2 and 10 J/cm 2 , accumulating five different series of shots, i.e., 1, 5, 10, 20 and 40. The damage to the a-C thin layer was investigated by atomic force microscopy (AFM) and Nomarski differential interference contrast (DIC) optical microscopy. The dependence of the single-shot-damaged area on pulse energy makes it possible to determine a beam spot diameter in the focus. Its value was found to be equal to (23.3±3.0) µm using AFM data, assuming the beam to have a Gaussian profile. Such a plot can also be used for a determination of single-shot damage threshold in a-C. A single-shot threshold value of 1.1 J/cm 2 was found. Investigating the consequences of the multiple-shot exposure, it has been found that an accumulation of 10, 20 and 40 shots at a fluence of 0.5 J/cm 2 , i.e., below the single-shot damage threshold, causes irreversible changes of thin a-C layers which can be registered by both the AFM and the DIC microscopy. In the center of the damaged area, AFM shows a-C removal to a maximum depth of 0.3, 1.2 and 1.5 nm for 10-, 20-and 40-shot exposure, respectively. A Raman micro-probe does not indicate any change in the structure of the remaining a-C material. The erosive behavior reported here contrasts with the material expansion observed earlier [L. Juha et al., Proc. SPIE 5917, 91 (2005)] on an a-C sample irradiated by a large number of femtosecond pulses of XUV high-order harmonics (HHs).

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Diamond-like bonds in amorphous hydrogenated carbon films induced by x-ray irradiation

Abstract: Articles you may be interested inOn the induced microstructure changes of the amorphous carbon nitride films during annealingThe effect of nitrogen incorporation on the bonding structure of hydrogenated carbon nitride films

Cited by 11 publications

References 17 publications

Evolution kinetics of sp2 ordering in tetrahedral amorphous carbon films induced by electron irradiation

Evolution kinetics of sp2 ordering in tetrahedral amorphous carbon films induced by electron irradiation

Direct Observation of X-ray Induced Atomic Motion Using Scanning Tunneling Microscope Combined with Synchrotron Radiation

Radiation damage to amorphous carbon thin films irradiated by multiple 46.9 nm laser shots below the single-shot damage threshold

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