排序方式: 共有24条查询结果,搜索用时 15 毫秒
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K. I. Rusakov A. A. Gladyshchuk Yu. P. Rakovich J. F. Donegan S. A. Filonovich M. J. M. Gomes D. V. Talapin A. L. Rogach A. Eychmüller 《Optics and Spectroscopy》2003,94(6):859-863
Efficient photoluminescence (PL) up-conversion in CdSe/ZnS quantum dots prepared by an organometallic approach is reported. It is demonstrated that the efficiency of photon energy up-conversion and the magnitude of the spectral shift can be controlled by (i) the thickness of the ZnS layers, (ii) the temperature dependence of the excited-state absorption coefficient, and (iii) the dependence on the excitation intensity. From the analysis of the experimental data, it is proposed that intrinsic gap states are involved as intermediate states in the PL up-conversion, rather than nonlinear two-photon absorption or Auger processes. 相似文献
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Sergey A. Filonovich Yurii P. Rakovich Mikhail I. Vasilevskiy Mikhail V. Artemyev Dmitrii V. Talapin Andrey L. Rogach Anabela G. Rolo Maria J. M. Gomes 《Monatshefte für Chemie / Chemical Monthly》2002,38(1):909-918
We present the results of a comparative analysis of the absorption and photoluminescence excitation (PLE) spectra vs. integrated photoluminescence (IPL) measured as a function of the excitation wavelength for a number of samples containing II–VI semiconductor nanocrystals (NCs) produced by different techniques. The structure of the absorption and PL spectra due to excitons confined in NCs and difficulties with the correct interpretation of the transmittance and PLE results are discussed. It is shown that, compared to the conventional PLE, the IPL intensity plotted against the excitation wavelength (IPLE spectra) reproduce better the structure of the absorption spectra. Therefore, IPLE spectroscopy can be successfully used for probing the quantized electron-hole (e-h) transitions in semiconductor nanocrystals. 相似文献
23.
Using a particular way of normalizing the orthogonal polynomials, which is most commonly encountered in the synthesis of filtering networks in communication and electronic engineering, two theorems concerning the extremal properties of orthogonal polynomials are first proved. The results are then applied to find the minimum value and the minimizing function for various definite integrals involving weight functions of classical orthogonal polynomials. 相似文献
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