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91.
T.-W. Pi L.-C. TienJ.-F. Wen C.-P. OuyangC.-P. Cheng J. Hwang 《Solid State Communications》2003,125(9):459-462
We have employed synchrotron radiation photoemission to investigate calcium fluoride deposited on Si(001)-2×1 annealed at 700 °C. The valence band spectra reveal that the initial molecules are dissociated to single Ca atoms resting on the surface. Si 2p core-level spectra manifest a negatively shifted Ca-induced line at 0.35 eV. The dissociated Ca atoms occupy only half of the surface, on top of which the CaF2 molecules commence growth. This is in contrast to the Si(111)-7×7 counterpart, which exhibits a CaF layer in the interface. Strong elastic scattering due to the absorbed Ca atoms is evident in the photoemission spectra, thus averaging out the angle-dependent features. 相似文献
92.
Nicolás de la Rosa-Fox Manuel Piñero Rocío Litrán Luis Esquivias 《Journal of Sol-Gel Science and Technology》2003,26(1-3):947-951
CdS semiconductor nanocrystals were grown as quantum dots (QDs) inside a silica matrix obtained by the sol-gelmethod and assisted in the mother liquid by high powerultrasounds. Small-angle neutron scattering (SANS) accountsfor a 3.6 nm crystal size homogeneously distributed. Optical excitation from the third harmonic of a Nd:YAG ns laser wasfocused on the sample to study the photoluminescence (PL) atroom temperature. The PL spectrum shows radiative processfrom intrinsic transitions and a broad band corresponding tothe traps. Variable stripe length (VSL) method was used to measure the optical gain spectra by the growth of theamplified luminescence. A broad optical gain spectrumproduced by the biexciton-exciton transitions revealing thestimulated emission from the CdS QDs. It is also observed ared-shift of the PL emission crystal size-dependent. 相似文献
93.
Calcium tin silicate, CaSnSiO5, called Malayaite is synthesized with equimolecular quantities of calcium oxide, silica and stannic oxide followed by a thermic
process. In this work, the synthesis of Malayaite and the structure of a Malayaite-based pigment, Sn/Co pink, is investigated
by X-ray diffraction and Mossbauer spectroscopy. The results indicate Malayaite and Cassiterite formation, but the ion cobalt
incorporated in the Malayaite structure, diminishes the Cassiterite proportion and causes larger asymmetry in the environment
of the tin atom. 相似文献
94.
NONLINEAROSCILIATIONANALYSISBYANORTHOGONALFUNCTIONMETHODSunPi,hong(孙丕忠)TangPiangang(唐乾刚)SunShixian(孙世贤)(NationUniversityofDef... 相似文献
95.
96.
珠光体材料由许多随机取向的珠光体团组成,每一珠光体团又由铁素体片和渗碳体片交替
叠合而成. 实验表明具有较小片层间距的珠光体材料具有较高的强度和寿命. 通过分析构成
珠光体团的各相及界面的损伤特征,利用损伤耗散功的概念,得到了铁素体、渗碳体与界面
损伤的具有统一形式的演化规律,将其嵌入基于细片层微结构和非经典塑性理论的珠光体团
的弹塑性本构方程,利用Hill自洽方法,得到了珠光体材料的损伤本构描述. 所得到的损
伤本构描述显含表征微结构特征的片层间距,容易证明具有较小片层间距的珠光体材料具有
较好的综合力学性能. 对珠光体材料的拉伸和循环拉压特性进行了分析,得到了与实验一
致的结果. 相似文献
97.
Rhodium(III)‐Catalyzed [3+2]/[5+2] Annulation of 4‐Aryl 1,2,3‐Triazoles with Internal Alkynes through Dual C(sp2)H Functionalization 下载免费PDF全文
Yuan Yang Ming‐Bo Zhou Xuan‐Hui Ouyang Rui Pi Dr. Ren‐Jie Song Prof. Dr. Jin‐Heng Li 《Angewandte Chemie (International ed. in English)》2015,54(22):6595-6599
A rhodium(III)‐catalyzed [3+2]/[5+2] annulation of 4‐aryl 1‐tosyl‐1,2,3‐triazoles with internal alkynes is presented. This transformation provides straightforward access to indeno[1,7‐cd]azepine architectures through a sequence involving the formation of a rhodium(III) azavinyl carbene, dual C(sp2)? H functionalization, and [3+2]/[5+2] annulation. 相似文献
98.
Phytochemical study of green walnut husks of Juglans mandshurica Maxim. led to the isolation of a new naphthalenone, (4R)-3,4-dihydro-4-butoxy-5-hydroxy-naphthalen-1(2H)-one (1), together with 16 known compounds. Compounds 4–6, 13, 14 and 17 were isolated from the genus Juglans for the first time, and their chemotaxonomic significance was also evaluated. 相似文献
99.
Dale McMorrow Michon Irons Wyche Pi Tai Chou Michael Kasha 《Photochemistry and photobiology》2015,91(3):576-585
Trace quantities of hydrogen‐bonding impurities in otherwise highly purified and dried glassy hydrocarbon matrices at 77 K can modify the relative triplet state energy levels, and hence the photophysical properties of two aromatic ketones, xanthone and chromone, to the extent that the intrinsic spectroscopic properties are obscured. The intrinsic spectroscopic properties of each are revealed in multicrystalline n‐alkane Shpol'skii matrices, and also can be observed in rigorously purified and dried hydrocarbon glasses at 77 K. The extreme sensitivity to stoichiometric, and even substoichiometric quantities of hydrogen‐bonding impurities arises from the near‐degeneracy of the two lowest‐lying triplet states, and the sensitive nature of the n→π* blueshift phenomena to specific hydrogen‐bonding interactions. 相似文献
100.
Yuan Yang Ming‐Bo Zhou Xuan‐Hui Ouyang Rui Pi Ren‐Jie Song Jin‐Heng Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(22):6695-6699
A rhodium(III)‐catalyzed [3+2]/[5+2] annulation of 4‐aryl 1‐tosyl‐1,2,3‐triazoles with internal alkynes is presented. This transformation provides straightforward access to indeno[1,7‐cd]azepine architectures through a sequence involving the formation of a rhodium(III) azavinyl carbene, dual C(sp2) H functionalization, and [3+2]/[5+2] annulation. 相似文献