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61.
62.
I.Y. Knoke P. Berwian E. Meissner J. Friedrich H.P. Strunk G. Müller 《Journal of Crystal Growth》2010,312(20):3040-3045
This work presents an experimental study on the identification and quantification of different types of dislocations in GaN grown by low-pressure solution growth. A reliable defect selective etching procedure in a NaOH-KOH melt is developed and validated using transmission electron microscopy that permits to define groups of etch pits that belong each to dislocations with a specific Burgers vector. This way a comparably fast method is provided for determining the total, the specific dislocation densities and the type of dislocation in a statistically representative way. The results for the solution grown samples are compared to those obtained for MOCVD GaN. 相似文献
63.
W. Beck A.Ya. Karasik J. Arvanitidis D. Ricard 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,10(1):131-140
High-temperature persistent spectral hole-burning (PSHB), up to room temperature, has been observed in a Eu
3+
-doped aluminosilicate glass using a high peak-power nanosecond dye laser. Spontaneous refilling as well as thermal cycling
measurements show that at least two mechanisms, a fast and a slow one, are involved in our sample. We suggest that the fast
or “easy” component may correspond to a non-photochemical local rearrangement of the host or to photoreduction of the Eu
3+
ions and that the second one leading to very stable photoproducts may correspond to transfer of an electron over a sizable
distance through a several-step process. The mechanisms we suggest agree with light-induced hole refilling measurements. Line
broadening mechanisms are discussed and the temperature-dependent part of the homogeneous width and of the spectral shift
is interpreted in terms of a two-phonon (Raman) process involving pseudo-local phonons.
Received 28 July 1999 相似文献
64.
We consider a first order linear partial differential operator of principal type on a closed connected orientable two-dimensional manifold sending sections of one complex line bundle to sections of another. We prove that the assumption of global hypoellipticity of the operator implies a relation between the degrees of the line bundles and the Euler characteristic of the manifold. 相似文献
65.
Arising from the proposed Transmission Line(TL) model for ERR and wire structure, a TL model for a metamaterial absorber is proposed. The S-parameters obtained by this TL model demonstrate the same shapes as the simulation. An investigation of the TL model and average absorption power densities shows that the metamaterial absorber does not simply convert the electromagnetic wave into thermal energy, but concentrate the electromagnetic wave into a small space where it is finally absorbed. This suggests that ... 相似文献
66.
First-order line-mixing coefficients and model relaxation matrix element scaling factors have been obtained for allowed transitions in the ν3 band Q branch of CH4 broadened by H2, He, N2, O2, Ar, and CH4. The broadening, shifting, Dicke-narrowing, and line-mixing parameters are determined by simultaneous least-squares fitting of spectra at pressures from 0.014 to 66.66 kPa recorded with a high-resolution difference-frequency laser. These results confirm, improve, and extend a previous analysis of the lower pressure (?13.3 kPa) data [A.S. Pine, J. Chem. Phys. 97 (1992) 773] which yielded averaged coefficients of individually fit spectra where adjacent broadened lines are still partially resolved. 相似文献
67.
Florian Pfender 《Discrete Mathematics》2009,309(9):2922-2924
We show that line graphs G=L(H) with σ2(G)≥7 contain cycles of all lengths k, 2rad(H)+1≤k≤c(G). This implies that every line graph of such a graph with 2rad(H)≥Δ(H) is subpancyclic, improving a recent result of Xiong and Li. The bound on σ2(G) is best possible. 相似文献
68.
Nitric acid (HNO3) plays an important role in the Earth’s atmosphere as a reservoir molecule of NOx species. It has a strong infrared signature at 11 μm which is one of the most commonly used for the infrared retrieval of this species in the atmosphere since this spectral region coincides with an atmospheric window. It is therefore essential to have high quality spectral parameters in this spectral region. For the H14NO3 (main) isotopic species, the 11 μm bands were already the subject of numerous extensive studies which involve not only the ν5 and 2ν9 cold bands but also the first hot bands. The present work is the first high resolution Fourier transform analysis of the 11 μm bands for H15NO3, which is the second most abundant isotopomer of nitric acid [a ≅ 0.00365(7)]. In this way, the analysis of the ν5 and 2ν9 cold bands centered at 871.0955 and 893.4518 cm−1 was performed, and as for H14NO3, these bands are significantly perturbed since rather strong resonances couple the 51 and 92 rotational levels. The theoretical model that we used to compute the line positions and line intensities is directly issued from the one which we used recently for H14NO3 [A. Perrin, J. Orphal, J.-M. Flaud, S. Klee, G. Mellau, H. Mäder, D. Walbrodt, M. Winnewisser, J. Mol. Spectrosc. 228 (2004) 375-391]. Actually, for the H15NO3 line positions, the Hamiltonian matrix accounts for the rather strong Fermi and the weaker Coriolis interactions linking the 51⇔92 rotational levels. Using this model which accounts correctly for the strong mixing of the 51 and 92 upper state energy levels, the ν5 and 2ν9 line intensities for H15NO3 were satisfactorily computed using the ν5 and 2ν9 transition moment operators achieved previously for the 14N (main) isotopic species. In this way, the transfer of intensities from the ν5 fundamental (and presumably strong) band to the 2ν9 overtone (and presumably weak) band could be explained for H15NO3 as it was done previously for the 14N (main) isotopic species. Finally, the position of the H15NO3ν5 + ν9 − ν9 hot band was identified at 875.245 cm−1. 相似文献
69.
Andrew Janca P.F. Bernath N.F. Zobov S.V. Shirin Oleg L. Polyansky Jonathan Tennyson 《Journal of Molecular Spectroscopy》2003,219(1):132-135
Fourier transform emission spectra were recorded using a mixture of H2O and D2O at a temperature of 1500 °C. The spectra were recorded in three overlapping sections and cover the wavenumber range 1800-3932 cm−1. This spectrum is analyzed together with a previously reported one spanning the 380-2190 cm−1 range [Parekunnel et al., J. Mol. Spectrosc. 2001 (28) 101]. This analysis leads to 4409 newly assigned HDO emission lines. This work particularly extends data on the (200) and (120) states of HDO for which newly determined energy levels are presented. 相似文献
70.
In modern telephone exchanges, subscriber lines are usually connected to the so-called subscriber line modules. These modules serve both incoming and outgoing traffic. An important difference between these two types of calls lies in the fact that in the case of blocking due to all channels busy in the module, outgoing calls can be queued whereas incoming calls get busy signal and must be re-initiated in order to establish the required connection. The corresponding queueing model was discussed recently by Lederman, but only the model with losses has been studied analytically. In the present contribution, we study the model which takes into account subscriber retrials and investigate some of its properties such as existence of stationary regime, derive explicit formulas for the system characteristics, limit theorems for systems under high repetition intensity of blocked calls and limit theorems for systems under heavy traffic. 相似文献