Monitoring of spectroscopic changes of a single trapped fission yeast cell by using a Raman tweezers set-up

We demonstrate an improvement of the sensitivity of a Raman tweezers set-up, which combines optical tweezers with Raman spectroscopy. The system was tested by taking the Raman spectrum of a 4.6 μm diameter polystyrene sphere trapped in an aqueous solution. The improvement of sensitivity of the set-up was achieved by adjusting the trap depth for maximum signal to noise ratio (SNR). The maximum SNR was obtained by investigating the Raman peak of a trapped polystyrene sphere at 1001 cm⁻¹ according to trap depth. With this system, a single trapped living Schizosaccharomyces Pombe yeast cell was sensitively monitored by taking the kinetic Raman spectra for more than 2 h. The relative intensity decrease in amide I and amide III bands, frequency increase in amide I band together with alterations in tyrosine marker band around 850 cm⁻¹ was observed, which indicates alterations in the hydration state of protein by time progressing.     

Investigation of micropipes in 6H-SiC by Raman scattering

The spectra of 6H-SiC crystals including micropipes have been examined for the Si face using Raman scattering. The first-order Raman features reveal that the intensity of the transverse optical phonon band centered at ∼796 cm⁻¹ is sensitive to the micropipes. And the second-order Raman features of the micropipes in bulk 6H-SiC are well-defined using the selection rules for second-order scattering in wurtzite structure. It is found that there are some second-order peaks missing for the micropipe-including sample, which may be induced by the reduction of the incident laser intensity at around the micropipe, especially the uneven surface in the inner wall of the micropipe. These features might also be employed to characterize other structural defects such as screw-dislocations and threading edge dislocations.     

Efficient vacuum-ultraviolet generation by anti-Stokes Raman scattering using a cryogenic Raman cell

We have investigated the increase of efficiency for high-order anti-Stokes Raman scattering using a cryogenic Raman cell. By cooling the cell to liquid-nitrogen temperature, output energies of the 9th-order anti-Stokes wave at 133 nm in normal hydrogen were enhanced by a factor of 10, and the 11th-order anti-Stokes line at 141 nm in normal deuterium appeared, while no output was observed at room temperature. No output energy enhancement, however, was obtained using cooled para-hydrogen as a result of multiple rotational Raman scattering. For long-term operation, the output window surface of the Raman cell was kept at above 200 K in order to protect it from deposition, the absorption of which is detrimental to VUV transmission.     

单个活态细胞显微激光拉曼散射光谱处理方法研究

单细胞激光共焦拉曼散射光谱由于受扫描条件、样品自身浓度以及样品分子组成等因素的影响,其谱线信噪比较低、荧光背景有时较明显从而导致谱线质量较差.本文主要针对活态单细胞的拉曼光谱进行谱线预处理技术研究用以提高谱线的信噪比、灵敏度及降低荧光背景干扰.首先是宇宙射线的去除,之后进行谱线的归类,这是提高谱线灵敏度的关键步骤;其次...     

玻璃中气泡成分的拉曼光谱分析①

利用拉曼探针分析绿色玻璃中气泡及正常玻璃，并与硫的标准拉曼光谱进行对比，结果表明，玻璃中气泡的主要成分是硫。并研究了产生气泡的原因，为消除气泡、提高玻璃质量、改善玻璃生产工艺提供了科学依据。     

Investigation of the Cr:LiSrAlF6 crystal by high-temperature Raman spectroscopy

In this paper, Cr-doped LiSrAlF₆ crystals are investigated using high-temperature Raman spectroscopy and the single-crystal Raman spectra of Cr:LiSrAlF₆ are analysed by factor group theory and comparison with other fluorides. The results indicate that Cr:LiSrAlF₆ is stable below its melting point; Raman peaks located at 561, 322 and 250 cm^-1 are assigned to the A_1g modes of AlF₆, SrF₆ and LiF₆ octachdra, respectively; with temperature increasing, Raman peaks associated with AlF₆ octahedra shift towards low frequencies, while LiF₆ and SrF₆ octahedra are temperature-insensitive; around the crystal melting point, three new Raman peaks occur, which are associated with the AlF₆ octahedral chain structure. Finally, the microstructural evolution of Cr:LiSrAlF₆ from room temperature to its melting point is discussed based on its Raman spectra.     

脱辅基细胞色素C构象的Raman散射研究

脱辅基细胞色素Ｃ构象的Ｒａｍａｎ散射研究童宇峰郁鉴源左晨周群（清华大学化学系北京１０００８４）ＩｎｖｅｓｔｉｇａｔｉｏｎｏｎｔｈｅＣｏｎｆｏｒｍａｔｉｏｎｏｆＡｐｏｃｙｔｏｃｈｒｏｍｅＣｂｙＲａｍａｎＳｐｅｃｔｒｏｓｃｏｐｙＴｏｎｇＹｕｆｅｎｇ，Ｙｕ...     

Investigation on microstructures of MnSix thin films by Raman spectroscopy

In this paper, Raman spectroscopy is used to study the microstructures of MnSi_x thin films annealed at different temperatures. Two phases of Mn silicides, MnSi_1.73 and MnSi, are identified, and their Raman spectra are reported. Each phase of Mn silicides shows a set of three well‐defined peaks at about 300 cm⁻¹ in the spectrum, which could be used as fingerprints in identifying the formation of the Mn silicides. Compared with conventional X‐ray diffraction method, Raman spectroscopy is found to be more sensitive to investigate the microstructures of Mn silicides, especially at the initial stage of formation of the Mn silicides. Copyright © 2008 John Wiley & Sons, Ltd.     

Investigation of surface passivation process on magnetic nanoparticles by Raman spectroscopy

A detailed study of the surface passivation process in superparamagnetic cobalt ferrite nanoparticles has been carried out using micro Raman spectroscopy. In addition to Raman spectroscopy, X-ray diffraction and atomic absorption spectroscopy were also used to investigate passivated and non-passivated samples. The data were discussed in terms of changes in the structural characteristics of the samples considering the introduction of Fe ions during the passivation. We found an improvement of the nanoparticle crystallinity due to the passivation process.     

Investigation of thermostability and phonon–phonon interactions in Mo6S3I6 nanowires by Raman scattering spectroscopy

Detailed Raman scattering measurements were performed on molybdenum–sulfur–iodine nanowires (Mo₆S₃I₆). At room temperature, 21 well‐resolved Raman modes were experimentally observed for the first time in this new compound. The phase stability and vibrational properties of the nanowires were investigated by different temperature treatments. High‐temperature Raman spectra showed that the phase separation of Mo₆S₃I₆ nanowires took place between 573 and 673 K, followed by appearance of a new mode at 819 cm⁻¹ characteristic of the MoO₃ phase. Low‐temperature Raman scattering spectra showed a significant difference in phonon–phonon interactions between internal and external Raman modes of Mo₆S₃I₆ nanowires. These interesting vibrational properties can give new insights for improved material preparation and achievement of higher conductivity and other functional properties of these otherwise interesting materials. Copyright © 2009 John Wiley & Sons, Ltd.     

Study of cell killing effect on S180 by ultrasound activating protoporphyrin IX

The present study was initiated to investigate the potential biological mechanism of cell killing effect on isolate sarcoma 180 (S180) cells induced by ultrasound activating protoporphyrin IX (PPIX). S180 cells were exposed to ultrasound for 30 s duration, at a frequency of 2.2 MHz and an acoustic power of 3 W/cm² in the presence of 120 μM PPIX. The viability of cells was evaluated using trypan blue staining. The generation of oxygen free radicals in cell suspensions was detected immediately after treatment using a reactive oxygen detection kit. A copper reagent colorimetry method was used to measure the level of FFAs released into cell suspensions by the process of cell damage induced by ultrasound and PPIX treatment. Oxidative stress was assessed by measuring the activities of key antioxidant enzymes (i.e., SOD, CAT, GSH-PX) in S180 tumor cells. Treatment with ultrasound and PPIX together increased the cell damage rate to 50.91%, while treatment with ultrasound alone gave a cell damage rate to 24.24%, and PPIX alone kept this rate unchanged. Colorimetry and enzymatic chemical methods showed that the level of FFAs in cell suspension increased significantly after the treatment, while the activity of all the above enzymes decreased in tumor cells at different levels, and were associated with the generation of oxygen free radicals in cell suspension after treatment. The results indicate that oxygen free radicals may play an important role in improving the membrane lipid peroxidation, degrading membrane phospholipids to release FFAs, and decreasing the activities of the key antioxidant enzymes in cells. This biological mechanism might be involved in mediating the effects on S180 cells and resulting in the cell damage seen with SDT.     

CVD法SiC纤维表面碳涂层结构的拉曼光谱研究

采用激光拉曼光谱仪和扫描电子显微镜对以C₂H₂+H₂和C₂H₂+C₃H₈+Ar为反应气体,通过直流加热化学气相沉积工艺在SiC纤维表面制备的碳涂层的微观结构及断口形貌进行了研究。结果表明,两种碳涂层的拉曼光谱中1 350,1 400～1 500和1 600 cm-1附近均观察到D,D”和G特征峰的存在。碳涂层具有类似石墨的片层结构,结构中微晶的排列显示出一定的无序性,并含有少量非晶态碳。随着沉积温度的升高,微晶尺寸有所增加,结构中的均匀性和有序度也得到改善。断口观察发现,采用C₂H₂+H₂制备的碳涂层平整、致密;而由C₂H₂+C₃H₈+Ar得到的碳涂层呈曲折的层片状。分析表明,这主要与结构中的有序度和均匀性有关。     

Investigation of the intramembrane distribution of chlorin e6 derivatives by using fluorescence quenching

Belarusian State University, 4, F. Skorina Ave., Minsk, 220050, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 2, pp. 179–187, March–April, 1995     

金刚石压腔结合拉曼光谱技术进行氢同位素分馏的实验研究

应用水热金刚石压腔结合拉曼光谱技术来进行石膏和重水间稳定同位素分馏的实验研究.氢同位素 D 与 H 的质量差百分比是所有稳定同位素里最大的,由质量引起的分馏更容易发生,更容易在实验中观测;石膏是浅部地壳重要的含水矿物,它与重水之间的同位素分馏效应对矿物-水体系的同位素平衡分馏研究具有重要意义.常用分馏系数是指两矿物或两...     

Dielectrophoretic behavior of a single cell when manipulated by optoelectronic tweezers: A study based on COMSOL ALE simulations

Optoelectronic tweezers uses optically induced dielectrophoretic (DEP) force for manipulating cells in aqueous solution, which has shown potential applications in biology and tissue engineering among other possibilities. To effectively design the optoelectronic tweezers (OETs) chip, detailed knowledge about the behavior of cells in response to DEP force in an aqueous layer is needed. In this paper, the trajectories of an SMMC-77721 cell, simulated as a rigid dielectric sphere, in the induced electric field of optical trapping are studied using both an Arbitrary Lagrangian-Eulerian (ALE) method and a particle-tracing method (PTM) available within the COMSOL multiphysics software platform. Because the ALE method involves solving the distorted electric field around the cell and taking a full account of the Maxwell stress tensor (MST), it is expected to provide more accurate predictions about the spherical cell velocity than PTM that involves dipole moment approximation. Our ALE results show noticeably greater cell velocity than that predicted by the classical DEP expression based on dipole moment approximation. The ALE model can help gain new insights for analyzing cell motions in aqueous solution under sophisticated optical spot patterns.     

拉曼光谱方法研究疏水作用对四甲基脲氢键形成的影响

测得了四甲基脲(TMU)与水,甲醇和乙醇及N,N-二甲基甲酰胺(DMF)与水二元体系的拉曼光谱,分析二元溶液混合体系中羰基伸缩振动的频移随体积比变化的规律,从光谱的变化中可以得出羰基频移经历两个阶段： 首先,羰基伸缩振动随体系中氢键受体体积比的增加向低波数方向移动;其次,当二元混合体系中体积比超过一个临界值后,羰基伸缩振动振动频率不变,变化的仅仅是相对强度。通过分析临界体积比可以得出TMU与水相互作用中水是以较大缔合分子形式存在;而TMU与甲醇、乙醇,DMF与水相互作用中是以单分子或小的缔合分子形式存在的。     

Investigation of weak damage in Al0.25Ga0.75As/GaAs by using RBS/C and Raman spectroscopy

The weak damage induced by 0.8 MeV Si ion implantation in the Al_0.25Ga_0.75As films epitaxially grown on GaAs substrates was studied by using Rutherford backscattering spectrometry/channeling (RBS/C) and Raman spectroscopy. RBS/C spectra measured from the implanted samples showed rather low damage level induced by the ion implantation with ion dose from 1×10¹⁴ to 5×10¹⁵ cm⁻². The Raman spectra were measured on these samples. Two kinds of phonon modes, GaAs-like and AlAs-like, are observed, which indicate the existence of multiple phonon vibrational modes in the epitaxial Al_0.25Ga_0.75As films on the GaAs substrate. Compared with the unimplanted sample, the Raman photon peaks for the implanted sample shift gradually to lower energy with the increase of the implantation dose. The strains induced in the implanted layer were also evaluated from the Raman spectra. The result from high resolution double crystal X-ray diffractometry (HRXRD) also verified the evolution of the strains in the implanted layers.     

1 342 nm激光泵浦光子晶体光纤受激喇曼散射的实验研究

利用调Q Nd∶GdVO4 激光器为泵浦源,对100 m非线性光子晶体光纤中受激拉曼散射谱的形成过程进行了实验研究.随着泵浦功率的增加,在中心~1 575 nm处得到一个宽带光谱,并观察到光谱内部出现能量红移现象,使得光谱能量从1 546 nm处转移到1 615 nm.     

固体催化剂表面酸类型的激光喇曼光谱特性研究

本文对离子型固体如多相催化载体的表面酸类型进行了吸附态的激光喇曼光谱特性的研究。并对不同类型的固体样品进行了考查,对表面脱附净化方法作了改进。实现了原位(In-Situ)测定并和真空法作了比较,实验结果证明喇曼光谱是研究多相催化剂表面酸性能的一种较好的方法,它不但能严格的区分开吡啶的物理吸附和化学吸附,而且能区别开是吸附在Bronsted酸位上还是Lewis酸位上。对不同类型的载体,催化剂和分子筛进行了测定,所得结果和其催化性能很好的关联。     

Effect of 6H-SiC （1120） substrate on epitaxial graphene revealed by Raman scattering

A nonpolar SiC(1120) substrate has been used to fabricate epitaxial graphene (EG). Two EGs with layer numbers of 8-10 (referred to as MLG) and 2-3 (referred to as FLG) were used as representative to study the substrate effect on EG through temperature dependent Raman scattering. It is found that Raman lineshifts of G and 2D peaks of the MLG with temperature are consistent with that of a free graphene predicted by theory calculation, indicating that the substrate influence on the MLG is undetectable. While Raman G peak lineshifts of the FLG to that of the free graphene are obvious, however, its lineshift rate (-0.016 cm^-1/K) is almost one third of that (-0.043 cm^-1/K) of a EG on 6H-SiC (0001) in the temperature range from 300 K to 400 K, indicating a weak substrate effect from SiC (1120) on the FLG. This renders the FLG a high mobility around 1812 cm²- ·V^-1-·s^-1 at room temperature even with a very high carrier concentration about 2.95× 10¹³ cm^-2 (p-type). These suggest SiC (1120) is more suitable for fabricating EG with high performance.