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61.
P.?K.?Ghosh S.?Das K.?K.?ChattopadhyayEmail author 《Journal of nanoparticle research》2005,7(2-3):219-225
Nanocrystallites of cadmium oxide (CdO) thin films were deposited by sol–gel dip coating technique on glass and Si substrates. XRD and TEM diffraction patterns confirmed the nanocrystalline cubic CdO phase formation. TEM micrograph of the film revealed the manifestation of nano CdO phase with average particle size lying in the range 1.6–9.3 nm. UV–Vis spectrophotometric measurement showed high transparency (nearly 75% in the wavelength range 500–800 nm) of the film with a direct allowed bandgap lying in the range 2.86–3.69 eV. Particle size has also been calculated from the shift of bandgap with that of bulk value for the films for which the particles sizes are comparable to Bohr exitonic radius. The particle size increases with the increase in annealing temperature and also the intensity of XRD peaks increases which implies that better crystallinity takes place at higher temperature.This revised version was published online in August 2005 with a corrected issue number. 相似文献
62.
A composition spread metal thin film fabrication technique based on ion beam sputter deposition method was developed. The technique enables us to fabricate any desired part or a complete binary/ternary composition spread metal thin films onto a single substrate by sequentially sputtering different target materials. Composition spread metal thin films can be deposited directly on a dielectric film in patterned electrode shape for C-V and I-V measurements. The system could be especially useful in the search for new multi-component metal gate materials. 相似文献
63.
Unidirectional transmission of light irrespective of its polarization by a two-dimensional annular photonic crystal in the form of a right prism is numerically demonstrated. Band structure of the crystal obtained through the plane-wave expansion method reveals a directional band gap along a principal axis, leading to prohibition of wave transmission in the reverse direction. In the forward direction, however, transmission of waves is facilitated by circumventing the directional band gap due to altered surface orientation. Polarization-independent unidirectional light transmission is demonstrated through finite-difference time-domain simulations. Unidirectional operation is enhanced and the polarization independence is established through the introduction of an anti-reflection coating layer, which increases the forward transmittances for both polarizations up to 0.44, such that a contrast ratio of 0.96 is attained at a free-space wavelength of 1.55 μm. Although polarization independence deteriorates, unidirectionality is preserved between 1.45 μm and 1.60 μm, provided that the angle of incidence remains between ?5° and +5°. Device performance is also influenced by the transverse source size, where leakage in the reverse direction may be suffered if the source width is beyond a critical value. 相似文献
64.
Exposure of powder forms of DL-2-aminoadipic acid and ammonium acetate to gamma radiation results in the formation of free radicals detected by the electron paramagnetic resonance spectroscopy at room temperature. In these compounds, the observed paramagnetic species were attributed to the HOOCCH2CH2CH2CHCOOH and CH2COONH4 radicals, respectively. The g values and the hyperfine coupling constants of the unpaired electron with the environmental protons were determined for these two radicals. In work, the observed paramagnetic species were found to be stable at room temperature for more than two months. Also, these compounds were characterised by FT-IR and UV–VIS. Their thermal stabilities were determined by TGA and DTA measurements. Thermal analyses were shown to be unstable of the HOOCCH2CH2CH2CH(NH2)COOH and CH3COONH4 against thermo-oxidative decomposition. 相似文献
65.
The electron paramagnetic resonance spectra of γ-irradiated powders of α-(methylamino)isobutyric acid – CH3NHC(CH3)2COOH, α -aminoisobutyric acid methyl ester hydrochloride – NH2(CH3)2CCOOCH3 HCl, and diethylmalonic acid – (CH3CH2)2C(COOH)2 have been investigated at room temperature. It has been found that γ -irradiation produces the (CH3)2C˙COOH radical in the first, the (CH3)2C˙COOCH3 radical in the second and the (CH3CH2)2C˙COOH radical in the third compound. The spectra were computer-simulated. The g values and the hyperfine coupling constants of the unpaired electron with the environmental methyl, methylene protons and OH proton were determined. The results were found to be in good agreement with the existing literature data and theoretical predictions. 相似文献
66.
67.
Ecaterina C. Niculescu Cristina Stan Gabriela Tiriba Cristina Truşcǎ 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(5):100
The electronic properties and optical characteristics – absorption coefficient, refractive index and group index – in an impurity doped pseudo-harmonic quantum disc subjected to an applied magnetic field are investigated. Numerical calculations are performed using the exact diagonalization technique and the compact density-matrix formalism. It is found that the chosen structure could be switched between a lambda-type and a ladder-type configuration by a proper tailoring of the magnetic field strength. Furthermore, the absorption profile and the associated slow light frequency range can be controlled not only by varying the control field amplitude and its detuning but also by changing the impurity position and the magnetic field strength. 相似文献
68.
Active-to-absorbing phase transition subjected to the velocity fluctuations in the frozen limit case
N. V. Antonov M. Hnatich A. S. Kapustin T. Lučivjanský L. Mižišin 《Physics of Particles and Nuclei Letters》2017,14(6):944-952
The directed bond percolation process is studied in the presence of compressible velocity fluctuations with long-range correlations. We discuss a construction of a field theoretic action and a way of obtaining its large scale properties using the perturbative renormalization group. The most interesting results for the frozen velocity limit are given. 相似文献
69.
We report the ac conductivity and relaxation behavior analysis for a heterogeneous polymer–clay nanocomposite (PNC) having
composition (polyacrylonitrile)8LiCF3SO3 + x wt.% dodecylamine modified montmorillonite. Charge transport behavior in an ionically conducting PNC has been analyzed systematically
and correlated with the macroscopic parameters like polymer glass transition temperature and available free mobile charge
carriers. Intercalation of cation coordinated polymer into the nanometric clay channels has been confirmed by high-resolution
transmission electron microscopy. The electrical properties of the intercalated PNC films have been studied using complex
impedance/admittance spectroscopy. Excellent correlation of relaxation behavior with polymer glass transition temperature
(T
g) confirmed the objectives of the work. An analysis of dielectric relaxation indicates that PNC films are lossy when compared
with polymer–salt film. This result is a direct outcome of faster ion dynamics leading to strong electrode polarization effect
due to the accumulation of charge carriers at the interface. 相似文献
70.
It has long been known that thiol-terminated molecules self-assemble as commensurate monolayers on Au(111) surfaces. By spreading floating octadecanethiol monolayers on aqueous solutions of chloroauric acid (HAuCl4) and using x rays to reduce the gold ions as well as to probe the structure, we have observed the nucleation of (111)-oriented Au nanoparticles at thiol surfaces. This process may be similar to the formation of biogenic gold by bacteria. The thiol monolayer acts as a "soft template," changing its structure as Au crystals form so that there is a sqrt[3]×sqrt[3] commensurate relationship. 相似文献