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Ultrafast carrier dynamics in GeSn thin film based on time-resolved terahertz spectroscopy
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作者 黄盼盼 张有禄 +3 位作者 胡凯 齐静波 张岱南 程亮 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第1期164-169,共6页
We measure the time-resolved terahertz spectroscopy of GeSn thin film and studied the ultrafast dynamics of its photo-generated carriers.The experimental results show that there are photo-generated carriers in GeSn un... We measure the time-resolved terahertz spectroscopy of GeSn thin film and studied the ultrafast dynamics of its photo-generated carriers.The experimental results show that there are photo-generated carriers in GeSn under femtosecond laser excitation at 2500 nm,and its pump-induced photoconductivity can be explained by the Drude–Smith model.The carrier recombination process is mainly dominated by defect-assisted Auger processes and defect capture.The firstand second-order recombination rates are obtained by the rate equation fitting,which are(2.6±1.1)×10^(-2)ps^(-1)and(6.6±1.8)×10^(-19)cm^(3)·ps^(-1),respectively.Meanwhile,we also obtain the diffusion length of photo-generated carriers in GeSn,which is about 0.4μm,and it changes with the pump delay time.These results are important for the GeSn-based infrared optoelectronic devices,and demonstrate that Ge Sn materials can be applied to high-speed optoelectronic detectors and other applications. 展开更多
关键词 GeSn thin film time-resolved THz spectroscopy ultrafast dynamics carrier recombination
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IN-SITU TIME-RESOLVED RAMAN SPECTROSCOPIC STUDIES OF SILVER ELECTRODE IN NaSCN SOLUTION
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作者 Wu Hu LI Zhong Qun TIAN State Key Laboratory for Physical Chemistry of the Solid Surface,Department of Chemistry,Xiamen University,Xiamen 361005Jing Song GAO Qi XUE Department of Chemistry,Nanjing University,Nanjing 210008 《Chinese Chemical Letters》 SCIE CAS CSCD 1993年第9期829-830,共2页
In-situ time-resolved Raman spectroscopy(TRRS)has been applied on studies of electrochemical adsorption of thiocyanate at silver electrode during potential cycles and potential step.It is shown that some dynamic infor... In-situ time-resolved Raman spectroscopy(TRRS)has been applied on studies of electrochemical adsorption of thiocyanate at silver electrode during potential cycles and potential step.It is shown that some dynamic information about the adsorption and desorption processes can be obtained. 展开更多
关键词 SERS IN-SITU time-resolved raman SPECTROSCOPIC STUDIES OF SILVER ELECTRODE IN NaSCN SOLUTION
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Distance-Dependent Long-Range Electron Transfer in Protein:a Case Study of Photosynthetic Bacterial Light-Harvesting Antenna Complex LH2 Assembled on TiO 2 Nanoparticle by Femto-Second Time-Resolved Spectroscopy
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作者 翁羽翔 张蕾 +9 位作者 杨健 全冬晖 汪力 杨国桢 藤井律子 小山泰 张建平 冯娟 余军华 张宝文 《Acta Botanica Sinica》 CSCD 2003年第4期488-493,共6页
The function of protein in long-range biological electron transfer is a question of debate. We report some preliminary results in femtosecond spectroscopic study of photosynthetic bacterial light-harvesting antenna co... The function of protein in long-range biological electron transfer is a question of debate. We report some preliminary results in femtosecond spectroscopic study of photosynthetic bacterial light-harvesting antenna complex assembled onto TiO2 nanoparticle with an average size of 8 nm in diameter. Crystal structure shows that photosynthetic bacterial antenna complex LH2 has a ring-like structure composed by alpha- and beta-apoprotein helices. The alpha- and beta-transmembrance helices construct two concentric cylinders with pigments bacteriochlorophyll a (Bchl a) and carotenoid (Car) buried inside the protein. We attempt to insert TiO2 nanoparticle into the cavity of the inner cylindrical hollow of LH2 to investigate the nature of the electron transfer between the excited-state Bchl a and the TiO2 nanoparticle. A significant decrease in the ground state bleaching recovery time constant for Bchl a at 850 run (B850) in respect to that of the Bchl a in free LH2 has been observed. By using the relation of distance-dependent long-range electron transfer rate in protein, the distance between the donor B850 and the acceptor TiO2 nanoparticle has been estimated, which is about 0.6 nm. The proposed method of assembling proteins onto wide-gap semiconductor nanoparticle can be a promising way to determine the role of the protein playing in biological electron transfer processes. 展开更多
关键词 TiO2 nanoparticle LH2 time-resolved spectroscopy charge transfer energy transfer protein
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Photochemical Reaction of Benzoin Caged Compound: Time-Resolved Fourier Transform Infrared Spectroscopy Study
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作者 代小娟 余友清 +1 位作者 刘坤辉 苏红梅 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2016年第1期91-98,I0002,共9页
The benzoin group caged compound has received strong interests due to its excellent photo- deprotection properties and wide use in chemical and biological studies. We used timeresolved infrared spectroscopy to investi... The benzoin group caged compound has received strong interests due to its excellent photo- deprotection properties and wide use in chemical and biological studies. We used timeresolved infrared spectroscopy to investigate the photochemical reaction of the benzoin caged compound, o-(2-methylbenzoyl)-DL-benzoin under 266 nm laser irradiation. Taking advantage of the specific vibrational marker bands and the IR discerning capability, we have detected and identified the uncaging product 2-methylbenzoic acid, and two intermediate radicals of benzoyl and 2-methylbenzoate benzyl in the transient infrared spectra. Our results provide spectral evidence to support the homolytic cleavage reaction of C-C=O bond in competition with the deprotection reaction. Moreover, the product yields of 2-methylbenzoic acid and benzoyl radical were observed to be affected by solvents and a largely water contalning solvent can be in favor of the deprotection reaction. 展开更多
关键词 BENZOIN Caged compound Photo-deprotection time-resolved infrared spectroscopy
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In situ infrared, Raman and X-ray spectroscopy for the mechanistic understanding of hydrogen evolution reaction
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作者 Andi Haryanto Kyounghoon Jung +1 位作者 Chan Woo Lee Dong-Wan Kim 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第3期632-651,I0014,共21页
Hydrogen production by water reduction reactions has received considerable attention because hydrogen is considered a clean-energy carrier,key for a sustainable energy future.Computational methods have been widely use... Hydrogen production by water reduction reactions has received considerable attention because hydrogen is considered a clean-energy carrier,key for a sustainable energy future.Computational methods have been widely used to study the reaction mechanism of the hydrogen evolution reaction(HER),but the calculation results need to be supported by experimental results and direct evidence to confirm the mechanistic insights.In this review,we discuss the fundamental principles of the in situ spectroscopic strategy and a theoretical model for a mechanistic understanding of the HER.In addition,we investigate recent studies by in situ Fourier transform infrared(FTIR),Raman spectroscopy,and X-ray absorption spectroscopy(XAS) and cover new findings that occur at the catalyst-electrolyte interface during HER.These spectroscopic strategies provide practical ways to elucidate catalyst phase,reaction intermediate,catalyst-electrolyte interface,intermediate binding energy,metal valency state,and coordination environment during HER. 展开更多
关键词 Hydrogen evolution reaction Infrared spectroscopy raman spectroscopy X-ray absorption spectroscopy Reaction mechanism
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Investigation on Exciton Relaxation Kinetics of ZnCulnS/ZnSe/ZnS Quantum Dots by Time-Resolved Spectroscopy Techniques
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作者 李雪璁 隋宁 张宇 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2015年第1期54-58,I0001,共6页
The exciton relaxation kinetics of ZnCuInS/ZnSe/ZnS quantum dots (QDs) is investigated by time-resolved spectroscopy techniques in detail. Based on the rate distribution model, the wavelength-dependent emission dyna... The exciton relaxation kinetics of ZnCuInS/ZnSe/ZnS quantum dots (QDs) is investigated by time-resolved spectroscopy techniques in detail. Based on the rate distribution model, the wavelength-dependent emission dynamics shows that the intrinsic exciton, the exciton in the interface defect state and that in donor-acceptor pair state (DAPS) together participate in the photoluminescence process of QDs, and the whole emission process is mainly dependent on the DAPS emission. Transient absorption data show that the intrinsic exciton and the interface defect species maybe together appear after excitation and the intensity-dependent Auger recombination process also exists in QDs at high excitation intensity. 展开更多
关键词 Quantum dots time-resolved spectroscopy Exciton relaxation kinetics
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Investigation on Binding between Cations and Amides using UV Raman Spectroscopy
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作者 Yi-xuan Liu Zhou-bing Wang +3 位作者 Jing-jing Wang Kang-zhen Tian Xin Meng Gui-lin Mao 《Chinese Journal of Chemical Physics》 SCIE EI CAS CSCD 2024年第4期539-544,I0094,共7页
The interaction of proteins with salt ions plays an important role in life activities.We used butyramide as a model molecule to investigate the interaction of protein backbones with cations.The experiment was performe... The interaction of proteins with salt ions plays an important role in life activities.We used butyramide as a model molecule to investigate the interaction of protein backbones with cations.The experiment was performed in an aqueous solution of metal chloride using UV Raman spectroscopy.It was found that well-hydrated metal cations(Ca^(2+),Mg^(2+))tend to bind to C=O in the amide bond,resulting in redistribution of the amide I band peaks.Specifically,the peak intensity ratio of 1655 cm^(-1)to 1610 cm^(-1)increases significantly with increasing concentrations.However,this phenomenon is not obviously observed in NaCl solution.Furthermore,we studied the effect of salt ions on the water structures.The addition of Ca^(2+)and Mg^(2+)is beneficial to the enhancement of the water signal at the 3400 cm^(-1)position,while the Na^(+)at the same concentration is not obvious.The results have shown that the interaction between cations and amides satisfies the following order:Ca^(2+)>Mg^(2+)>Na^(+),which conforms to the Hofmeister series. 展开更多
关键词 UV raman spectroscopy Butyramide Hofmeister
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Rapid and real-time analysis of multi-component dissolved gas in seawater by Raman spectroscopy combined with continuous gas-liquid separator
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作者 Dewang Yang Wenhua Li +5 位作者 Lei Guo Yuhang Ji Yanzhe Gong Junwei Chu Libin Du Yongmei Wang 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2024年第9期146-153,共8页
Rapid and sensitive detection of dissolved gases in seawater is quite essential for the investigation of the global carbon cycle.Large quantities of in situ optical detection techniques showed restricted measurement e... Rapid and sensitive detection of dissolved gases in seawater is quite essential for the investigation of the global carbon cycle.Large quantities of in situ optical detection techniques showed restricted measurement efficiency,owing to the single gas sensor without the identification ability of multiple gases.In this work,a novel gas-liquid Raman detection method of monitoring the multi-component dissolved gases was proposed based on a continuous gas-liquid separator under a large difference of partial pressure.The limit of detection(LOD)of the gas Raman spectrometer could arrive at about 14 μl·L^(-1)for N_(2)gas.Moreover,based on the continuous gas-liquid separation process,the detection time of the dissolved gases could be largely decreased to about 200 s compared with that of the traditional detection method(30 min).Effect of equilibrium time on gas-liquid separation process indicated that the extracted efficiency and decay time of these dissolved gases was CO_(2)>O_(2)>N_(2).In addition,the analysis of the relationship between equilibrium time and flow speed indicated that the decay time decreased with the increase of the flow speed.The validation and application of the developed system presented its great potential for studying the components and spatiotemporal distribution of dissolved gases in seawater. 展开更多
关键词 Dissolved gas Rapid quantitative analysis Gas-liquid separator Gas-liquid raman spectroscopy
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Simultaneous measurements of global vibrational spectra and dephasing times of molecular vibrational modes by broadband time-resolved coherent anti-Stokes Raman scattering spectrography 被引量:2
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作者 尹君 于凌尧 +3 位作者 刘星 万辉 林子扬 牛憨笨 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第1期385-391,共7页
In broadband coherent anti-Stokes Raman scattering (CARS) spectroscopy with supercontinuum (SC), the simultaneously detectable spectral coverage is limited by the spectral continuity and the simultaneity of variou... In broadband coherent anti-Stokes Raman scattering (CARS) spectroscopy with supercontinuum (SC), the simultaneously detectable spectral coverage is limited by the spectral continuity and the simultaneity of various spectral components of SC in an enough bandwidth. By numerical simulations, the optimal experimental conditions for improving the SC are obtained. The broadband time-resolved CARS spectrography based on the SC with required temporal and spectral distributions is realised. The global molecular vibrational spectrum with well suppressed nonresonant background noise can be obtained in a single measurement. At the same time, the measurements of dephasing times of various molecular vibrational modes can be conveniently achieved from intensities of a sequence of time-resolved CARS signals. It will be more helpful to provide a complete picture of molecular vibrations, and to exhibit a potential to understand not only both the solvent dynamics and the solute-solvent interactions, but also the mechanisms of chemical reactions in the fields of biology, chemistry and material science. 展开更多
关键词 coherent anti-Stokes raman scattering photonic crystal fibre SUPERCONTINUUM molecular vibrational spectrum dephasing time time-resolved measurement
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A Highly Sensitive Femtosecond Time-Resolved Sum Frequency Generation Vibrational Spectroscopy System with Simultaneous Measurement of Multiple Polarization Combinations 被引量:2
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作者 谈军军 罗毅 叶树集 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2017年第6期671-677,I0002,共8页
Characterization of real-time and ultrafast motions of the complex molecules at surface and interface is critical to understand how interracial molecules function. It requires to develop surface-sensitive, fast-identi... Characterization of real-time and ultrafast motions of the complex molecules at surface and interface is critical to understand how interracial molecules function. It requires to develop surface-sensitive, fast-identification, and time-resolved techniques. In this study, we employ several key technical procedures and successfully develop a highly sensitive femtosecond time-resolved sum frequency generation vibrational spectroscopy (SFG-VS) system. This system is able to measure the spectra with two polarization combinations (ssp and ppp, or psp and ssp) simultaneously. It takes less than several seconds to collect one spectrum. To the best of our knowledge, it is the fastest speed of collecting SFG spectra reported by now. Using the time-resolved measurement, ultrafast vibrational dynamics of the N-H mode of α-helical peptide at water interface is determined. It is found that the membrane environment does not affect the N-H vibrational relaxation dynamics. It is expected that the time-resolved SFG system will play a vital role in the deep understanding of the dynamics and interaction of the complex molecules at surface and interface. Our method may also provide an important technical proposal for the people who plan to develop time-resolved SFG systems with simultaneous measurement of multiple polarization combinations. 展开更多
关键词 Femtosecond time-resolved Sum frequency generation vibrational spectroscopy Ultrafast vibrational dynamics Multiple polarization combination measurement CHIRAL
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Polarization Dependent Time-Resolved Infrared Spectroscopy and Its Applications
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作者 张文凯 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2016年第1期1-9,I0001,共10页
Polarization dependent time-resolved infrared (TRIR) spectroscopy has proven to be a useful technique to study the structural dynamics in a photochemical process. The angular information of transient species is obta... Polarization dependent time-resolved infrared (TRIR) spectroscopy has proven to be a useful technique to study the structural dynamics in a photochemical process. The angular information of transient species is obtainable in this measurement, which makes it a valuable technique for the investigation of electron distribution, molecular structure, and conformational dynamics. In this review, we briefly introduce the principles and applications of polarization dependent TRIR spectroscopy. We mainly focused on the following topics: (i) an overview of TRIR spectroscopy, (ii) principles of TRIR spectroscopy and its advantages compared to the other ultrafast techniques, (iii) examples that use polarization dependent TRIR spectroscopy to probe a variety of cheinical and dynamical phenomena including protein conformational dynamics, excited state electron localization, and photoisomerization, (iv) the limitations and prospects of TRIR spectroscopy. 展开更多
关键词 Ultrafast spectroscopy Infrared spectroscopy POLARIZATION time-resolved infrared spectroscopy
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Time-resolved infrared spectroscopic investigation of Ga_(2)O_(3) photocatalysts loaded with Cr_(2)O_(3)-Rh cocatalysts for photocatalytic water splitting 被引量:1
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作者 Qian Ding Tao Chen +2 位作者 Zheng Li Zhaochi Feng Xiuli Wang 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 2021年第5期808-816,共9页
Investigation of the charge dynamics and roles of cocatalysts is crucial for understanding the reaction of photocatalytic water splitting on semiconductor photocatalysts.In this work,the dynamics of photogenerated ele... Investigation of the charge dynamics and roles of cocatalysts is crucial for understanding the reaction of photocatalytic water splitting on semiconductor photocatalysts.In this work,the dynamics of photogenerated electrons in Ga_(2)O_(3) loaded with Cr_(2)O_(3)-Rh cocatalysts was studied using time-resolved mid-infrared spectroscopy.The structure of these Cr_(2)O_(3)-Rh cocatalysts was identified with high-resolution transmission electron microscopy and CO adsorption Fourier-transform infrared spectroscopy,as Rh particles partly covered with Cr_(2)O_(3).The decay dynamics of photogenerated electrons reveals that only the electrons trapped by the Rh particles efficiently participate in the H2 evolution reaction.The loaded Cr_(2)O_(3) promotes electron transfer from Ga_(2)O_(3) to Rh,which accelerates the electron-consuming reaction for H2 evolution.Based on these observations,a photocatalytic water-splitting mechanism for Cr_(2)O_(3)-Rh/Ga_(2)O_(3) photocatalysts has been proposed.The elucidation of the roles of the Cr_(2)O_(3)-Rh cocatalysts aids in further understanding the reaction mechanisms of photocatalytic water splitting and guiding the development of improved photocatalysts. 展开更多
关键词 Photocatalysis time-resolved mid-infrared spectroscopy Carrier dynamics Overall water splitting COCATALYST Gallium oxide
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Time-resolved spectroscopy of collinear femtosecond and nanosecond dual-pulse laser-induced Cu plasmas 被引量:1
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作者 Qiuyun WANG Hongxia QI +3 位作者 Xiangyu ZENG Anmin CHEN Xun GAO Mingxing JIN 《Plasma Science and Technology》 SCIE EI CAS CSCD 2021年第11期121-127,共7页
In this paper,we investigate the time-resolved spectroscopy of collinear femtosecond(fs)and nanosecond(ns)dual-pulse(DP)laser-induced plasmas.A copper target was used as an experimental sample,and the fs laser was con... In this paper,we investigate the time-resolved spectroscopy of collinear femtosecond(fs)and nanosecond(ns)dual-pulse(DP)laser-induced plasmas.A copper target was used as an experimental sample,and the fs laser was considered as the time zero reference point.The interpulse delay between fs and ns laser beams was 3μs.First,we compared the time-resolved peak intensities of Cu(I)lines from Cu plasmas induced by fs+ns and ns+fs DP lasers with collinear configuration.The results showed that compared with the ns+fs DP,the fs+ns DP laser-induced Cu plasmas had stronger peak intensities and longer lifetimes.Second,we calculated time-resolved plasma temperatures using the Boltzmann plot with three spectral lines at Cu(I)510.55,515.32 and 521.82 nm.In addition,time-resolved electron densities were calculated based on Stark broadening with Cu(I)line at 521.82 nm.It was found that compared with ns+fs DP,the plasma temperatures and electron densities of the Cu plasmas induced by fs+ns DP laser were higher.Finally,we observed images of ablation craters under the two experimental conditions and found that the fs+ns DP laser-produced stronger ablation,which corresponded to stronger plasma emission. 展开更多
关键词 laser-induced breakdown spectroscopy fs+ns and ns+fs dual-pulse time-resolved spectroscopy plasma temperature electron density
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Coherent coupling between vibrational modes of C-H bonds at different positions studied by femtosecond time-resolved coherent anti-Stokes Raman scattering 被引量:1
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作者 杜鑫 何兴 +2 位作者 刘玉强 王英惠 杨延强 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第3期248-251,共4页
We performed femtosecond time-resolved coherent anti-Stokes Raman scattering (fs-CARS) measurements on liquid toluene and PVK film. For both samples, we selectively excited the CH stretching vibrational modes and ob... We performed femtosecond time-resolved coherent anti-Stokes Raman scattering (fs-CARS) measurements on liquid toluene and PVK film. For both samples, we selectively excited the CH stretching vibrational modes and observed the expected quantum beat signals. The frequency of the well-defined beats is in good agreement with the energy difference between the two simultaneously excited modes, which demonstrates that a coherent coupling between the vibrational modes of the C H chemical bonds exists at the different positions of the molecules. The dephasing times of the excited modes are obtained simultaneously. 展开更多
关键词 femtosecond time-resolved coherent anti-Stokes raman scattering coherent coupling quantum beat
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Detection of K in soil using time-resolved laser-induced breakdown spectroscopy based on convolutional neural networks 被引量:1
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作者 Chengxu LU Bo WANG +3 位作者 Xunpeng JIANG Junning ZHANG Kang NIU Yanwei YUAN 《Plasma Science and Technology》 SCIE EI CAS CSCD 2019年第3期108-113,共6页
One of the technical bottlenecks of traditional laser-induced breakdown spectroscopy(LIBS) is the difficulty in quantitative detection caused by the matrix effect. To troubleshoot this problem,this paper investigated ... One of the technical bottlenecks of traditional laser-induced breakdown spectroscopy(LIBS) is the difficulty in quantitative detection caused by the matrix effect. To troubleshoot this problem,this paper investigated a combination of time-resolved LIBS and convolutional neural networks(CNNs) to improve K determination in soil. The time-resolved LIBS contained the information of both wavelength and time dimension. The spectra of wavelength dimension showed the characteristic emission lines of elements, and those of time dimension presented the plasma decay trend. The one-dimensional data of LIBS intensity from the emission line at 766.49 nm were extracted and correlated with the K concentration, showing a poor correlation of R_c^2?=?0.0967, which is caused by the matrix effect of heterogeneous soil. For the wavelength dimension, the two-dimensional data of traditional integrated LIBS were extracted and analyzed by an artificial neural network(ANN), showing R_v^2?=?0.6318 and the root mean square error of validation(RMSEV)?=?0.6234. For the time dimension, the two-dimensional data of time-decay LIBS were extracted and analyzed by ANN, showing R_v^2?=?0.7366 and RMSEV?=?0.7855.These higher determination coefficients reveal that both the non-K emission lines of wavelength dimension and the spectral decay of time dimension could assist in quantitative detection of K.However, due to limited calibration samples, the two-dimensional models presented over-fitting.The three-dimensional data of time-resolved LIBS were analyzed by CNNs, which extracted and integrated the information of both the wavelength and time dimension, showing the R_v^2?=?0.9968 and RMSEV?=?0.0785. CNN analysis of time-resolved LIBS is capable of improving the determination of K in soil. 展开更多
关键词 quantitative DETECTION potassium(K) SOIL time-resolved LASER-INDUCED breakdown spectroscopy(LIBS) convolutional neural networks(CNNs)
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Rapid analysis of Chinese steamed bread staling using Raman Spectroscopy
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作者 Tong Sang Yong-Hui Yu Xiao-Dan Liu 《Food and Health》 2024年第3期42-47,共6页
Staling is an important issue that Chinese steamed bread(CSB)may encounter during storage,which significantly affects their taste,flavor,and nutritional value.The monitoring technology for rapid aging is particularly ... Staling is an important issue that Chinese steamed bread(CSB)may encounter during storage,which significantly affects their taste,flavor,and nutritional value.The monitoring technology for rapid aging is particularly important to effectively control the aging process of CSB,reduce quality deterioration,and promote the industrial production of CSB.Raman spectroscopy has been widely used in the study of food structure and properties due to its non-destructive and high-sensitivity characteristics,particularly demonstrating unique advantages in the analysis of starch structure.This study explored the possibility of analyzing the staling of CSB using Raman spectroscopy based on hardness and moisture content.Analysis of the correlation between the hardness of CSB and the full width at half maximum(FWHM)at 480 cm^(−1)during storage was conducted,and a significant positive correlation between them was found,with R^(2)above 0.8.Besides,nine characteristic peaks of CSB samples related to starch were selected for analysis.As the moisture content of CSB decreased,the peak intensities and areas of showed an upward trend during storage,with the best correlation coefficient above 0.8 revealed by linear regression analysis.Therefore,Raman spectra could be used as a potential method for the fast prediction of CSB staling. 展开更多
关键词 Chinese steamed bread STALING HARDNESS moisture content raman spectroscopy
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Time-resolved spectroscopy for 5s^('4)D_(7/2) state transitions undergoing electron–ion recombination in femtosecond laser-produced copper plasma
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作者 宋海英 李辉 +5 位作者 张艳杰 谷鹏 刘海云 李维 刘勋 刘世炳 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第12期290-294,共5页
In the femtosecond laser-produced Cu-plasma, the transient transition dynamics that the excited state 5s4D7/2 via electron-ion recombination transfers to 4p4F9/20 (465.11 nm, Λ1 line) and 4p4D7/20 (529.25 nm, Λ2 ... In the femtosecond laser-produced Cu-plasma, the transient transition dynamics that the excited state 5s4D7/2 via electron-ion recombination transfers to 4p4F9/20 (465.11 nm, Λ1 line) and 4p4D7/20 (529.25 nm, Λ2 line) states are investigated by using the time-resolved spectroscopy. The occupation number and relevant lifetime of the excited state 5s4D7/2, the temporal evolutions of spectral intensities for Λ1 line and Λ2 line emissions are demonstrated to be in direct proportion to the employed laser intensity, which reveals the transient features of transition dynamics clearly differing from that resulted in the traditional collision excitation. Furthermore, some unique characteristics for Λ1 and Λ2 transitions stemming from electron-ion recombination are examined in detail. 展开更多
关键词 time-resolved spectroscopy recombination transition laser-produced plasma
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Theoretical and experimental investigations of coherent phonon dynamics in sapphire crystal using femto-second time-resolved coherent anti-Stokes Raman scattering
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作者 杜鑫 张明福 +4 位作者 何兴 孟庆琨 宋云飞 杨延强 韩杰才 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第12期315-321,共7页
We report on the theoretical and the experimental investigations of the coherent phonon dynamics in sapphire crystal using the femtosecond time-resolved coherent anti-Stokes Raman scattering (fs-CARS) technique. The... We report on the theoretical and the experimental investigations of the coherent phonon dynamics in sapphire crystal using the femtosecond time-resolved coherent anti-Stokes Raman scattering (fs-CARS) technique. The temporal chirped white-light continuum (WLC) is used for the Stokes pulse, therefore we can perform the selective excitation of the phonon modes without using a complicated laser system. The expected quantum beat phenomenon is clearly observed. The theoretical formulas consist very well with the experimental results. The dephasing times of the excited phonon modes, the wavenumber difference, and the phase shift between the simultaneously excited modes are obtained and discussed. This work opens up a way to study directly high-frequency coherent phonon dynamics in bulk crystals on a femtosecond time scale and is especially helpful for understanding the nature of coherent phonons. 展开更多
关键词 coherent phonon femtosecond time-resolved coherent anti-Stokes raman scattering DEPHASING quantum beat
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Evaluation on residual stresses of silicon-doped CVD diamond films using X-ray diffraction and Raman spectroscopy 被引量:11
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作者 陈苏琳 沈彬 +2 位作者 张建国 王亮 孙方宏 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2012年第12期3021-3026,共6页
The effect of silicon doping on the residual stress of CVD diamond films is examined using both X-ray diffraction (XRD) analysis and Raman spectroscopy measurements. The examined Si-doped diamond films are deposited o... The effect of silicon doping on the residual stress of CVD diamond films is examined using both X-ray diffraction (XRD) analysis and Raman spectroscopy measurements. The examined Si-doped diamond films are deposited on WC-Co substrates in a home-made bias-enhanced HFCVD apparatus. Ethyl silicate (Si(OC2H5)4) is dissolved in acetone to obtain various Si/C mole ratio ranging from 0.1% to 1.4% in the reaction gas. Characterizations with SEM and XRD indicate increasing silicon concentration may result in grain size decreasing and diamond [110] texture becoming dominant. The residual stress values of as-deposited Si-doped diamond films are evaluated by both sin2ψ method, which measures the (220) diamond Bragg diffraction peaks using XRD, with ψ-values ranging from 0° to 45°, and Raman spectroscopy, which detects the diamond Raman peak shift from the natural diamond line at 1332 cm-1. The residual stress evolution on the silicon doping level estimated from the above two methods presents rather good agreements, exhibiting that all deposited Si-doped diamond films present compressive stress and the sample with Si/C mole ratio of 0.1% possesses the largest residual stress of ~1.75 GPa (Raman) or ~2.3 GPa (XRD). As the silicon doping level is up further, the residual stress reduces to a relative stable value around 1.3 GPa. 展开更多
关键词 silicon-doped diamond films silicon doping residual stress X-ray diffraction raman spectroscopy
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Raman spectroscopy and ionic structure of Na_3AlF_(6-)Al_2O_3 melts 被引量:6
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作者 胡宪伟 曲俊月 +3 位作者 高炳亮 石忠宁 刘风国 王兆文 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第2期402-406,共5页
Raman spectrum of molten cryolite was recorded. Based on the new understanding of the scattering coefficients, contents of various structural entities in acidic NaF-AlF3 melts at 942-1 024 ℃ in previous research were... Raman spectrum of molten cryolite was recorded. Based on the new understanding of the scattering coefficients, contents of various structural entities in acidic NaF-AlF3 melts at 942-1 024 ℃ in previous research were reanalyzed. The new quantitative analysis results show that when cryolite ratio(CR) is less than 2, AlF4- is the dominant anion in the melts, and its mole fraction is about 0.70 for melts with CR=1.5 and 0.50 for melts with CR=2. When CR is more than 2.5, the mole fraction of AlF6^3- is relatively large, which is around 0.45 for melts with CR=2.5. Ionic structure of Na3AlF6-Al2O3 melts was investigated by UV-Raman spectroscopy. Octahedral AlF6^3- and tetrahedral AlF4- are proved to exist with possible partial replacement of F- by O^2-. Al2O2F4^2- with a large scattering coefficient also exists in the melts in which alumina concentration is more than 4% (mass fraction). The increase of temperature causes blue-shift of the bands in the Raman spectra. 展开更多
关键词 raman spectroscopy Na3AlF6-Al2O3 melts scattering coefficient complex ion aluminum electrolysis sealed cell
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