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1.
Carbon coatings were deposited by atmospheric plasma jet. Influence of the distance between the exit of the plasma gun and a substrate (consequently temperature of the substrate) on properties of the coatings was investigated. The coatings deposited near to the exit of the plasma gun are porous with columnar structure, moderate hardness (∼10 GPa), and the lowest hydrogen (∼7 at.%) concentration. The coatings deposited at the larger standoff distance (>5 mm) have higher hydrogen (≤25 at.%) content and graphite-like structure. Most of the hydrogen in all coatings is bonded to the sp3 carbon (70-60 at.%) and predominantly forms methylene compounds. Decrease of standoff distance yields lower concentration of sp3 CH3 compounds and relative increase of amount of hydrogenated sp2 rings. 相似文献
2.
Electrical conduction in the temperature range of 120–370 K has been studied in sandwiched structures of Al/Ta2O5/Si. The tantalum oxide films were prepared by evaporation of tantalum on a p-Si crystal substrate, followed by oxidation
at a temperature of 600°C. The temperature-dependent current-voltage (I–V) characteristics are explained on the basis of a phonon-assisted tunnelling model. The same explanation is given for I–V data measured on Ta2O5 films by other investigators. From the comparison of experimental data with theory the density of states in the interface
layer is derived and the electron-phonon interaction constant is assessed.
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3.
Alfonsas Juška 《国际化学动力学杂志》2008,40(5):253-258
A nonhyperbolic model of Rabin (Biochem J 1967, 102, 22C–23C) in which four conformational states are considered has been simplified to the three‐state one. Only multistate models (if the concentration of enzyme or receptor is assumed to be low) can yield nonhyperbolic kinetics. The simplified model has been shown to retain all the essential properties of the original four‐state model. The model yields a diversity of nonhyperbolic dose–response curves both with higher and lower steepness than that of Henri‐type ones. The three‐state model can be further reduced to the hyperbolic one by making identical the different (unliganded) states. The bistate model in which protein concentration is assumed to be high yields nonhyperbolic kinetics as well; the model is reduced to the hyperbolic one if the protein concentration is assumed to be low. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 253–258, 2008 相似文献
4.
Zenonas Navickas Minvydas Ragulskis Alfonsas Vainoras Rasa Smidtaite 《Communications in Nonlinear Science & Numerical Simulation》2012,17(11):4430-4438
The effect of explosive divergence in generalized iterative maps of matrices is defined and described using formal algebraic techniques. It is shown that the effect of explosive divergence can be observed in an iterative map of square matrices of order 2 if and only if the matrix of initial conditions is a nilpotent matrix and the Lyapunov exponent of the corresponding scalar iterative map is greater than zero. Computational experiments with the logistic map and the circle map are used to illustrate the effect of explosive divergence occurring in iterative maps of matrices. 相似文献
5.
The amorphous hydrogenated carbon films (a-C:H) were obtained on Si (1 1 1) wafers by plasma jet chemical vapor deposition (PJCVD). a-C:H coatings have been prepared at 1000 Pa in argon/acetylene mixture. The Ar/C2H2 gas volume ratio varied from 1:1 to 8:1. It was demonstrated that by varying the Ar/C2H2 ratio the composition, growth rate of the coatings, and consequently the structure of the film, can be controlled. The growth rate and surface porosity of coatings deposited at Ar/C2H2 = 8:1 ratio decrease slightly with an increase in the distance between the plasma torch nozzle and substrate from 0.04 to 0.095 m. The transmittance of the coatings in the IR region of 2.5–25 μm slightly increases, while the absorption peaks at 2850–2960 cm?1 related with sp3 CH2–3 modes remain unchanged with an increase in the distance. The Raman spectroscopy indicated that the a-C:H coating formed at the Ar/C2H2 = 8:1 and 0.06 m has the highest sp3 C–C fraction. The proposed PJCVD technique allows to achieve the growth rates up to 300 nm/s. 相似文献
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7.
V. Nagirnyi G. Geoffroy R. Grigonis S. Guizard M. Kirm A. Kotlov L.L. Nagornaya M. Nikl V. Sirutkaitis S. Vielhauer 《Radiation measurements》2010,45(3-6):262-264
The relaxation of electronic excitations in CdWO4 and CaWO4 crystals was studied using the method of time-resolved interferometry with 100-fs temporal resolution at temperatures 15–295 K. The electronic system was excited in the one-photon and two-photon regime within the excitonic band in CaWO4 and in the electron-hole continuum in CdWO4. Immediate trapping of charge carriers was detected under pumping in the excitonic band of CaWO4. This result is in agreement with decay kinetics measurements with nanosecond time resolution under direct creation of excitons by 100-fs laser pulses. Fast relaxation of charge carriers followed by formation of excitons was observed in CdWO4. The comparison with previous work allows suggesting the formation of bulk excitons and surface-perturbed excitons in the multi-photon and one-photon regime. The corresponding models of self-trapped exciton creation in tungstate crystals are discussed. 相似文献
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9.
Sergey Markov Vitali Nagirnyi Andrey Vasil’ev Vladimir Makhov Raul Laasner Sebastian Vielhauer Marco Kirm Rimantas Grigonis Valdas Sirutkaitis 《Central European Journal of Physics》2012,10(4):1002-1008
The analytical expressions for the three-dimensional spatial distribution of excitons and luminescence decay kinetics of wide band-gap crystals were derived taking into account the saturation effect for absorption near the centre of the incident laser beam with Gaussian transversal profile. The model is verified for the excitonic emission of CdWO4 crystals under excitation by ultra-short laser pulses in the region of weak excitonic absorption. 相似文献
10.
Alfonsas Grigonis Liutauras Marcinauskas Vinga Vinciunaite Gediminas Raciukaitis 《Central European Journal of Physics》2011,9(5):1344-1350
The effect of a nanosecond laser irradiation of thin (60 and 145 nm) amorphous, diamond-like carbon films deposited on Si
substrate by an ion beam deposition (IBD) from pure acetylene and acetylene/hydrogen (1:2) gas mixture was analyzed in this
work. The films were irradiated with the infrared (IR) and ultraviolet (UV) radiation of the nanosecond Nd:YAG lasers working
at the first (1.16 eV) and the third (3.48 eV) harmonics, using a multi-shot regime. The IR laser irradiation stimulated a
minor increase in the fraction of sp2 bonds, causing a slight decrease in the hardness of the films and initiated SiC formation. Irradiation with the UV laser
caused the formation of carbides and increased hydrogenization of the Si substrate and the fraction of sp2 sites. Spalliation and ablation were observed at a higher energy density and with a large number of laser pulses per spot. 相似文献