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981.
982.
983.
S.-J. An W.I. Park G.-C. Yi S. Cho 《Applied Physics A: Materials Science & Processing》2002,74(4):509-512
High-quality ZnO thin films were grown on single-crystalline Al2O3(0001) and amorphous SiO2/Si(100) substrates at 400–640 °C using laser molecular beam epitaxy. For film growth, the third harmonics of a pulsed Nd:YAG
laser were illuminated on a ZnO target. The ZnO films were epitaxially grown on Al2O3(0001) with the narrow X-ray diffraction full width at half maximum (FWHM) of 0.04° and the films on SiO2/Si(100) exhibited a preferred c-axis orientation. Furthermore, the films exhibited excellent optical properties in photoluminescence
(PL) measurements with very sharp excitonic and weak deep-level emission peaks. At 15 K, PL FWHM values of the films grown
on Al2O3(0001) and SiO2/Si(100) were 3 and 18 meV, respectively.
Received: 8 May 2001 / Accepted: 18 September 2001 / Published online: 20 December 2001 相似文献
984.
985.
在RHF/6-31G、B3LYP/6-31G和MP2/6-31G水平下优化了标题化合物的平均几何构型,用B3LYP/6-31G方法计算了该化合物的红外光谱.并用GIAO分别在B3LYP/6-31G、B3LYP/6-311G和B3LYP/6-311++G水平对该化合物的核磁共振谱进行了研究.计算结果与实验结果吻合很好.同时对在合成过程中发现的两个中间产物进行了理论计算,研究证实了合成标题化合物时中间产物的存在. 相似文献
986.
How fast speakers can change pitch voluntarily is potentially an important articulatory constraint for speech production. Previous attempts at assessing the maximum speed of pitch change have helped improve understanding of certain aspects of pitch production in speech. However, since only "response time"--time needed to complete the middle 75% of a pitch shift--was measured in previous studies, direct comparisons with speech data have been difficult. In the present study, a new experimental paradigm was adopted in which subjects produced rapid successions of pitch shifts by imitating synthesized model pitch undulation patterns. This permitted the measurement of the duration of entire pitch shifts. Native speakers of English and Mandarin participated as subjects. The speed of pitch change was measured both in terms of response time and excursion time-time needed to complete the entire pitch shift. Results show that excursion time is nearly twice as long as response time. This suggests that physiological limitation on the speed of pitch movement is greater than has been recognized. Also, it is found that the maximum speed of pitch change varies quite linearly with excursion size, and that it is different for pitch rises and falls. Comparisons of present data with data on speed of pitch change from studies of real speech found them to be largely comparable. This suggests that the maximum speed of pitch change is often approached in speech, and that the role of physiological constraints in determining the shape and alignment of F0 contours in speech is probably greater than has been appreciated. 相似文献
987.
988.
J. Sha N. L. Wang C. F. Zhu Z. H. He X. H. Chen G. E. Zhou L. Z. Cao Q. R. Zhang H. R. Yi H. C. Li 《Applied Physics A: Materials Science & Processing》1992,54(3):300-302
Nonlinear I–V characteristics of YBa2Cu3O
y
epitaxial film at different temperatures in a magnetic field of up to 5T and angles between the direction of the field and the a–b plane of 0°, 30°, 45°, 60°, and 90° were measured. We find that there are the vortex glass phase and vortex liquid phase in the mixed state. The flux creep exists in the vortex glass phase, and it obviously appears in the area around the boundary between the vortex glass phase and the vortex liquid phase. 相似文献
989.
腔靶转换区辐射温度测量及定标关系 总被引:4,自引:1,他引:4
对近年来的激光腔靶实验的辐射温度作了综合分析和研究。对多种不同类型的柱型腔靶,在波长1.06μm的各种激光条件(不同的能量和脉宽)下,测量了腔靶转换区的辐射温度,并研究了辐射温度作为入腔激光能量、脉宽及腔靶转换区内表面积函数的定标关系。 相似文献
990.
本文报道板条激光器的热稳运行,在150W至10000W的泵浦功率下输出发散角基本保持不变,最大输出功率大于150W;并绘出了腔内插入柱面镜,以压缩输出激光发散角的初步结果. 相似文献