Time-and frequency-resolved broadband transient grating(BB-TG) spectroscopy is used to distinguish between ground-and excite-electronic state vibrational coherence at different wavelengths. Qualitative theoretical ana...Time-and frequency-resolved broadband transient grating(BB-TG) spectroscopy is used to distinguish between ground-and excite-electronic state vibrational coherence at different wavelengths. Qualitative theoretical analysis using double-sided Feynman diagrams indicates that a superposition of ground and excited state vibrational coherence are contained in the ground state absorption(GSA) and stimulated emission(SE) overlap band, while only the excited state is contained in the excited state absorption(ESA) band. The TG experiment, in which a white light continuum(WLC) is adopted as a probe, is conducted with rhodamine101(Rh101~+) as the target molecule. Fourier analysis of TG dynamics in a positive delay time range at specific wavelengths enables us to distinguish the low-frequency vibrational modes of Rh101 in ground-and excite-electronic states.展开更多
Conventional and low-frequency Raman spectra of series of anatase TiO2 gels,which were prepared by sol-gel method in diffrent conditions, were measured. Xerogel and aerogel TiO2 were prepared by natural dry and superc...Conventional and low-frequency Raman spectra of series of anatase TiO2 gels,which were prepared by sol-gel method in diffrent conditions, were measured. Xerogel and aerogel TiO2 were prepared by natural dry and supercritical dry respectively.Conventional Raman Spectra show that the width of peaks of TiO2 was almost broaden linearly with its particle size decreased down to several nm and a few new peaks were observed. The phenomena can be explained as the effect of particle size and occurrence of new surface structure. It can be used as a method of determination of small particle size. Low-frequency Raman scattering shows that from the intensity of spectra, the fractal dimension of nanocrystal xerogels and aerogels can be obtained by comparing with the base intensity. Low frequency Raman peaks give the information of particle size, acoustic velocity and polydispersibility about gel samples. More detailed woks were undergoing in our laboratory.展开更多
Orthorhombic copper polysilicate, CuSiO3, is isotypic to the spin-Peierls compound CuGeO3 and represents a further example of a quasi-one-dimensional spin = 1/2 antiferromagnetic Heisenberg chain system. This is a rep...Orthorhombic copper polysilicate, CuSiO3, is isotypic to the spin-Peierls compound CuGeO3 and represents a further example of a quasi-one-dimensional spin = 1/2 antiferromagnetic Heisenberg chain system. This is a representation of the first Raman and IR/FIR spectra for CuSiO3, measured at room temperature on polycrystalline samples. A comparison of the optical phonons, predicted by a factor group analysis, with those observed for the CuGeO3 prototype, is presented. A mode assignment for the silicate is given. Surface effects due to a very small crystallite size may cause additional broad bands observed in the Raman spectrum of CuSiO3. From the analysis of the Davydov doublet an intralayer-to-interlayer bond strength of about 40 is derived for the silicate, which is about 20% lower than for the isotypic germanate, allowing for different magnetic responses at low temperature.展开更多
青藏高原的大气热源及其影响以及环流的低频振荡已有很多探讨,但有关高原大气热源低频振荡及其对环流影响的研究目前尚未充分开展。利用倒算法计算得到的大气热源总量(Q1),诊断和分析1981—2000年夏季青藏高原东部逐日大气热源(Q1ETP,Q1...青藏高原的大气热源及其影响以及环流的低频振荡已有很多探讨,但有关高原大气热源低频振荡及其对环流影响的研究目前尚未充分开展。利用倒算法计算得到的大气热源总量(Q1),诊断和分析1981—2000年夏季青藏高原东部逐日大气热源(Q1ETP,Q1 of the eastern Tibetan Plateau)的主要振荡周期及其对应的传播特征,并取其中1985、1992年进行更详细的分析。结果表明:(1)夏季高原东部大气热源存在两种低频振荡,主要为10～20 d振荡(BWO,Quasi-Biweekly Oscillation),其次为30～60 d振荡(LFO,Low Frequency Oscillation)。(2)在1985、1992年中,高原热源低频振荡与当地降水低频振荡有很好的同位相谱相关,表明热源低频振荡很可能由凝结潜热的振荡激发的,这证明了本文热源数据的可靠性。(3)高原在夏季主要是振荡源地,但也接受外来影响。高原热源BWO生成后主要在原地维持振荡,并受来自孟加拉湾的热源BWO影响,有时部分振荡向外(主要向东)传播;热源LFO情况与BWO类似,以本地振荡为主但也受来自东部大陆LFO的影响,外传时则主要向西。所以研究高原热源低频振荡需要特别注意热源BWO。展开更多
基金Project supported by the Science Challenge Project,China(Grant No.TZ2016001)the National Natural Science Foundation of China(Grant No.21673211)
文摘Time-and frequency-resolved broadband transient grating(BB-TG) spectroscopy is used to distinguish between ground-and excite-electronic state vibrational coherence at different wavelengths. Qualitative theoretical analysis using double-sided Feynman diagrams indicates that a superposition of ground and excited state vibrational coherence are contained in the ground state absorption(GSA) and stimulated emission(SE) overlap band, while only the excited state is contained in the excited state absorption(ESA) band. The TG experiment, in which a white light continuum(WLC) is adopted as a probe, is conducted with rhodamine101(Rh101~+) as the target molecule. Fourier analysis of TG dynamics in a positive delay time range at specific wavelengths enables us to distinguish the low-frequency vibrational modes of Rh101 in ground-and excite-electronic states.
文摘Conventional and low-frequency Raman spectra of series of anatase TiO2 gels,which were prepared by sol-gel method in diffrent conditions, were measured. Xerogel and aerogel TiO2 were prepared by natural dry and supercritical dry respectively.Conventional Raman Spectra show that the width of peaks of TiO2 was almost broaden linearly with its particle size decreased down to several nm and a few new peaks were observed. The phenomena can be explained as the effect of particle size and occurrence of new surface structure. It can be used as a method of determination of small particle size. Low-frequency Raman scattering shows that from the intensity of spectra, the fractal dimension of nanocrystal xerogels and aerogels can be obtained by comparing with the base intensity. Low frequency Raman peaks give the information of particle size, acoustic velocity and polydispersibility about gel samples. More detailed woks were undergoing in our laboratory.
文摘Orthorhombic copper polysilicate, CuSiO3, is isotypic to the spin-Peierls compound CuGeO3 and represents a further example of a quasi-one-dimensional spin = 1/2 antiferromagnetic Heisenberg chain system. This is a representation of the first Raman and IR/FIR spectra for CuSiO3, measured at room temperature on polycrystalline samples. A comparison of the optical phonons, predicted by a factor group analysis, with those observed for the CuGeO3 prototype, is presented. A mode assignment for the silicate is given. Surface effects due to a very small crystallite size may cause additional broad bands observed in the Raman spectrum of CuSiO3. From the analysis of the Davydov doublet an intralayer-to-interlayer bond strength of about 40 is derived for the silicate, which is about 20% lower than for the isotypic germanate, allowing for different magnetic responses at low temperature.
文摘青藏高原的大气热源及其影响以及环流的低频振荡已有很多探讨,但有关高原大气热源低频振荡及其对环流影响的研究目前尚未充分开展。利用倒算法计算得到的大气热源总量(Q1),诊断和分析1981—2000年夏季青藏高原东部逐日大气热源(Q1ETP,Q1 of the eastern Tibetan Plateau)的主要振荡周期及其对应的传播特征,并取其中1985、1992年进行更详细的分析。结果表明:(1)夏季高原东部大气热源存在两种低频振荡,主要为10～20 d振荡(BWO,Quasi-Biweekly Oscillation),其次为30～60 d振荡(LFO,Low Frequency Oscillation)。(2)在1985、1992年中,高原热源低频振荡与当地降水低频振荡有很好的同位相谱相关,表明热源低频振荡很可能由凝结潜热的振荡激发的,这证明了本文热源数据的可靠性。(3)高原在夏季主要是振荡源地,但也接受外来影响。高原热源BWO生成后主要在原地维持振荡,并受来自孟加拉湾的热源BWO影响,有时部分振荡向外(主要向东)传播;热源LFO情况与BWO类似,以本地振荡为主但也受来自东部大陆LFO的影响,外传时则主要向西。所以研究高原热源低频振荡需要特别注意热源BWO。
基金“One Belt and One Road” Resource Environment Satellite Remote Sensing Interpretation and Application(DD20160117)Deep exploration technology and experimental research(SinoProbe-09-06)Comprehensive remote sensing information product development and application demonstration(201511078-04)
