便携式拉曼光谱仪用于合成大麻素类物质快速定性分析探究

我国于2021年7月将合成大麻素类物质整类列入管制,在一线查缉现场对疑似合成大麻素样品进行快速定性分析是办案民警的迫切需求。研究系统考察了拉曼光谱对合成大麻素的整体区分能力,比较了四款手持式拉曼光谱仪分析实际缴获样品时的结果差异,探讨了制约拉曼光谱在一线查缉现场广泛应用的原因。ProTT-EZRaman-A7便携式拉曼光谱仪的整体性能介于台式拉曼和手持式拉曼之间,选用该仪器采集了90种合成大麻素对照品的拉曼光谱,并利用兼容性强的KnowItAll软件建立了90种合成大麻素通用拉曼光谱库。分析90种合成大麻素的拉曼光谱,结果表明,当不存在荧光干扰时,拉曼光谱可以区分所有合成大麻素物质,但对部分结构相差一个甲基、卤素原子等的结构类似物区分度欠佳。不同款拉曼光谱仪的性能差异大,为考察其原因,本研究选用了四款手持式拉曼光谱仪分别对120份实际缴获合成大麻素样品进行了测定,随后使用KnowItAll软件并选用包含90种合成大麻素的通用拉曼光谱库对每张光谱图进行谱库检索。四款手持式拉曼光谱仪的正确匹配率分别为71.7%, 68.3%, 46.7%和24.2%。抗荧光干扰能力和分辨率的不同是造成不同...     

Open Raman Cell to Avoid Window Damage

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Open Raman Cell to Avoid Window Damage

An open Raman cell was designed to avoid the window damage in high power Raman amplifiers. The conversion efficiency and the beam quality of the Stokes pulse were measured as a function of time when Raman gases flowed out from the Raman cell. The effects of Raman gas density and diameter of Raman cell on the specification were also discussed. The results showed that this open Raman cell was useful for high power Raman system.     

Generation of a sub-20-fs single optical pulse by four-wave Raman mixing using two Raman cells filled with molecular hydrogen

To attempt to expand the spectral domain for pulse shortening, we generated several emission lines by stimulated Raman scattering and subsequent four-wave Raman mixing. The efficiency of generation of the Raman emission was improved by passing the beam through two Raman cells that were connected in series. The group-velocity dispersion induced by a Raman cell window and hydrogen was compensated for by means of a pair of chirped mirrors for pulse compression. By a phase lock of the emission lines in the process of four-wave Raman mixing, the pulse width was reduced from 114 to 17 fs in the second Raman cell.     

Raman spectroscopic analysis of cataract lens: A compendious review

Age-related cataracts is a pressing health issue with the increase in elderly populations. This creates an imminent demand for the development of an early, noninvasive method of cataracts diagnosis. Early detection of cataracts will improve quality of life and may prevent morbidity associated with advanced cataracts and surgery. Raman spectrum of proteins provides characteristic information regarding molecular interactions of peptide residues. Hence Raman spectroscopy is a promising tool for the study of protein-related diseases, such as cataracts. We surveyed the literature to assess the use of Raman technology in the studies of human lens and animal models. These studies included analysis of amino acids (i.e., cysteine, tryptophan, and tyrosine, etc.) and secondary protein structures (i.e., α-helix and β-sheet) in various Raman profiles. Other studies used Raman spectroscopy to analyze and monitor the development of cataracts in lens. Technological advances in the instrumentation of laser Raman spectroscopy, including Fourier transform Raman spectroscopy, Raman microspectroscopy, and confocal Raman microspectroscopy have improved the performance of Raman spectroscopic analysis. How to take advantage of these developments and make it closer to reality using Raman spectroscopic methods to diagnose cataracts in a timely manner is a key challenge for the scientific community of Raman spectroscopy.     

Signal-to-noise ratio of Raman signal measured by multichannel detectors

Raman spectroscopy has been widely used to characterize the physical properties of two-dimensional materials(2 DMs). The signal-to-noise ratio(SNR or S/N ratio) of Raman signal usually serves as an important indicator to evaluate the instrumental performance rather than Raman intensity itself. Multichannel detectors with outstanding sensitivity, rapid acquisition speed and low noise level have been widely equipped in Raman instruments for the measurement of Raman signal. In this mini-review, we first introduce the recent advances of Raman spectroscopy of 2 DMs. Then we take the most commonly used CCD detector and IGA array detector as examples to overview the various noise sources in Raman measurements and analyze their potential influences on SNR of Raman signal in experiments. This overview can contribute to a better understanding on the SNR of Raman signal and the performance of multichannel detector for numerous researchers and instrumental design for industry, as well as offer practical strategies for improving spectral quality in routine measurement.     

拉曼光谱检测生物大分子损伤的研究进展

拉曼光谱是基于拉曼散射效应而发展起来的一种光谱分析技术,体现的是分子的振动或转动信息。由于拉曼光谱技术与常规化学分析技术相比,具有对样品无损、样品制备简单和所需样品量少等特点,广泛用于生物大分子结构变化的研究。拉曼光谱不仅可以用于蛋白质、核酸和脂类等生物大分子损伤的快速检测,而且可以用于癌症的诊断与手术治疗。通过对比正常组织与癌变组织的拉曼光谱,可以找到两种组织特征吸收峰的差异,从而为癌症的最终确诊和确定肿瘤切除范围提供重要信息。文章综述了拉曼光谱检测生物大分子损伤的研究进展,介绍了利用表面增强拉曼光谱、傅里叶变换拉曼光谱和紫外共振拉曼光谱等技术在检测蛋白质二级结构、膜脂及DNA损伤中的应用,并展望了未来拉曼光谱技术的发展前景。     

部分临床药物的拉曼光谱研究

针对目前临床药物拉曼光谱的缺乏和药物检测领域的现状,利用拉曼光谱技术对抗生素、抗组织胺、血凝酶和止吐剂等几类常用临床药物进行了拉曼光谱的测量和研究。通过观测上述具有良好拉曼活性的药物样品拉曼光谱,不仅确定了样品拉曼峰的位移、强度和线宽,还探索了其包络的线形等光谱特性。通过分析和比较拉曼光谱图,找出各药物间的异同; 对于那些由于拉曼活性低或拉曼光谱的复杂样品,虽然暂时无法识别,但也进行了尝试性的测量或提出了测量建议。研究表明: 小分子药物的光谱特征很明显,拉曼峰分布较广, 对其进行光谱识别简单易行; 而大分子都表现出较弱的光谱特征峰, 常常伴随复杂的包络,不仅导致了对其光谱识别的困难, 也很难准确确定特征峰位置。对于不同药物,提出了用拉曼光谱测量和分析其药物成分的可行性,并通过分析其拉曼光谱的特性, 为医学工作者识别和分析药物成分提供了实验证据。不仅为建立药物的拉曼光谱数据库奠定了基础。还使业界看到了快速识别和检测药物的前景,从而促进拉曼光谱技术在药物检测上的运用。     

水下拉曼光谱探测低通滤光片水拉曼信号抑制

拉曼光谱作为研究物质结构的一个强有力工具,被广泛应用于水环境物质的检测,近年在深海原位探测中也得到应用.文章针对水下拉曼光谱探测的需要,设计了用于水的O-H振动拉曼信号抑制的低通滤光片,经过计算,边缘为指数形式的低通滤光片可较好的满足需要,而且通过实际采用的低通滤光片的实验证明,采用低通滤光片后水的O-H振动拉曼信号得...     

多波长消荧光拉曼光谱仪的研制及应用研究

拉曼光谱技术作为探究分子、晶体及其结构特征的有力手段,具有快速、无损、样品用量小、无需前处理且适应性强等优点,已被广泛应用于食品安全、石油化工等领域。但在拉曼光谱应用中,常常受到荧光背景干扰,导致拉曼信号降低,严重的情况下拉曼信号甚至会淹没在荧光背景中。为解决拉曼技术在实际应用中荧光背景干扰的问题,从仪器角度出发,采用二色镜对多波长拉曼光谱进行光路耦合设计,研制了近红外拉曼光谱与移频差分拉曼复合一体的多波长消荧光拉曼光谱检测系统,其中近红外拉曼光谱采用1 064 nm激光光源设计,移频差分拉曼光谱选取784.5和785.5 nm两组激光光源进行时分复用,在移频差分拉曼光谱检测的同时,亦可获得两组单波长拉曼光谱数据。通过对比同步测试和分时逐次测试的强度及峰位稳定性,验证了多波长消荧光拉曼光谱仪的同步测试性能;选取了多种荧光背景强弱不同的样品,进行了单波长拉曼、近红外拉曼及移频差分拉曼光谱的对比分析。针对丙酮、乙腈等荧光背景较弱的样品,可采用单波长拉曼光谱对样品进行定量及定性分析;针对食用油、红色塑胶微粒等荧光背景与拉曼信号强度相当的样品,可采用近红外拉曼光谱对样品进行定量及定性分析;针对红酒、棕色塑胶微粒等荧光背景较强的样品,需结合近红外拉曼光谱和差分拉曼光谱对样品进行定性分析。研究表明：通过多波长消荧光拉曼光谱检测系统的研制,在常规单波长拉曼光谱技术的基础上,将两种抑制荧光干扰技术有机结合,有效扩充了应用领域及样品检测范围。     

Experimental study of the Raman strain rosette based on the carbon nanotube strain sensor

This work presents a new technique named Raman strain rosette for the micro‐strain measurement of both Raman active and Raman inactive materials. The technique is based on the theoretical model of the carbon nanotube (CNT) strain sensor that applies the resonance and polarization Raman properties of CNTs and calculates the synthetic contributions of uniformly dispersed CNTs to the entire Raman spectrum. In our work, the proposed technique is applied in different experiments on the Raman inactive materials, such as step‐by‐step uniaxial tensile and Raman mapping around a circular hole. The experimental results reached by the Raman strain rosette are consistent with the actual values as a whole. This study verifies that the Raman strain rosette is applicable to quantitative measurement of all the in‐plane components of the strain tensor (including both normal and shear strains) by three polarized Raman detections for each sampling spot on a microscale. The technique is further applicable to achieving the strain fields through Raman mapping. Copyright © 2010 John Wiley & Sons, Ltd.     

二元混合溶液闪点行为的激光拉曼光谱研究

本文以乙醇-甲酰胺,乙腈-甲酰胺,乙醇-环己酮,乙腈-环己酮四种混合溶液为研究对象,采用激光拉曼光谱对四种溶液体系的闪点行为进行讨论和研究。通过测定四种溶液体系的拉曼光谱和闪点,结合溶液拉曼光谱的特征峰强度比和拉曼位移的变化,探索四种溶液闪点的变化规律。试验结果表明,随着溶液浓度的增大,溶质的拉曼特征峰强线性增加,混合溶液的闪点降低。采用三次多项式分别对四种溶液体系的闪点与拉曼特征峰、溶液浓度的关系进行拟合,拟合结果良好。混合溶液的闪点随拉曼特征峰强比、溶液浓度的变化趋势相同。该试验方法将有助于从分子结构角度分析混合溶液的闪点变化规律,同时该方法可用于混合溶液闪点的实时在线检测。     

基于最大似然法的共焦拉曼光谱成像方法

随着现代科技对纳米微观区域兴趣的增加,如DNA测序、分子纳米器件微结构检测等,其对拉曼光谱技术的空间分辨力提出了更高的要求,而现有共焦拉曼光谱技术受自身原理限制,空间分辨力已无法满足科学需求。针对这一问题,在现有共焦拉曼光谱技术的基础上,提出一种基于最大似然算法的共焦拉曼光谱成像方法。该方法将超分辨图像复原技术与共焦拉曼光谱技术相结合,利用基于Poisson-Markov约束的最大似然超分辨复原算法对共焦拉曼光谱图像进行超分辨图像复原处理,恢复图像高频成分,进而改善共焦拉曼光谱系统的空间分辨能力,实现超分辨成像。仿真分析和实验结果表明,提出的基于最大似然算法的共焦拉曼光谱成像方法在不改变现有共焦拉曼光谱系统光学结构的前提下,仅对单幅拉曼光谱图像进行超分辨图像复原处理,即可将系统空间分辨力提高到200 nm,实现超分辨成像,同时该方法具有较强的噪声抑制能力。该方法有效地提高了共焦拉曼光谱系统的空间分辨力,为物理化学、材料科学等前沿领域中的高空间分辨微区光谱探测提供了一种新的途径,是一种行之有效的高空间分辨的共焦拉曼光谱成像方法。     

Raman scattering from one-dimensional carbon systems

Although the Raman effect was discovered nearly 80 years ago, it is only recently that the special characteristics of Raman scattering for one-dimensional systems have been seriously considered. This review focuses on the special interest of the Raman effect for one-dimensional systems that is of particular relevance to carbon nanostructures. Two examples of Raman scattering in one-dimensional systems are given. The first illustrates the use of Raman spectroscopy to reveal the remarkable structure and properties of carbon nanotubes arising from their one-dimensionality. Some of the recent advances in using Raman spectroscopy to study doping and intercalation to modify nanotube properties are reviewed, in the context of a one-dimensional system. The second example is the Raman spectra of a linear chain of carbon atoms and the special properties of this interesting system. New approaches toward applying Raman spectroscopy to carbon nanostructures are also emphasized.     

Applications of Raman Spectroscopy in Agricultural Products and Food Analysis: A Review

Abstract

Raman spectroscopy has been gaining popularity as an analytical tool due to advances in development of Raman spectrometry and the power of personal computers. Due to to its narrow and highly resolved bands, Raman spectroscopy allows for nondestructive extraction of chemical and physical information about samples and aids in rapid on-line analysis without any special sample preparation. In this review, Raman spectroscopic techniques such as dispersive Raman spectroscopy, Fourier transform Raman spectroscopy, surface-enhanced Raman spectroscopy, and spatially offset Raman spectroscopy are briefly introduced. In addition, applications of Raman spectroscopy are explored, within various fields of agricultural products and food, including fruits and vegetables, crops, meat and dairy products, oil, as well as beverages. In addition, some discussion on the importance of Raman spectroscopy as fundamental and applied research of agricultural products and food is provided.     

活体植物中β-胡萝卜素分子的二级拉曼散射谱

利用显微拉曼光谱技术对从法国梧桐树新鲜采集得到的树叶做了测试分析，在可见光514.5nm激发下，不对样品做任何提纯，直接得到了树叶中β－胡萝卜素分子的一级和二级拉曼光谱。根据对β－胡萝卜素分子拉曼散射位于2000－3100cm^-1之间和2000cm^-1以下谱线的仔细分析对比，得到了二级拉曼谱和一级谱的倍频、和频关系。实验研究表明，控制样品表面的激光强度和信号积分时间，不破坏活体树叶中的分子结构和构象，这为研究植物在不同的环境生长状况提供一种实时实地测量技术。此外讨论了用共焦显微拉曼研究活体植物的优点及限制。     

单层纳米碳管振动模的拉曼光谱研究

测量了单层纳米碳管的一级、二级拉曼光谱.在40—3300cm^-1范围内观测到18条一级拉曼谱线和7条二级拉曼谱线,理论所预言的谱线几乎全被观测到,谱峰位置和理论值符合得很好.通过和理论值的对照,对这些谱线作了初步标定.所观测到的单层纳米碳管的拉曼激活振动模数目及二级拉曼谱线条数都是迄今最多的. 关键词：     

Raman spectroscopy based on a single-crystal sapphire fiber

We demonstrate the advantages of using a single-crystal sapphire fiber to perform Raman spectroscopy over using a standard glass fiber. The narrow Raman peaks and the low background signal of a single-crystal sapphire fiber allow for the detection of weaker Raman signals or Raman signals much closer to the incident laser wavelength than with a standard glass fiber, which has a strong broadband Raman spectrum of its own. The Raman spectra of calcite, single-walled carbon nanotubes, and aqueous sodium carbonate solution were collected using a 50 cm long, 200 μm diameter sapphire fiber, and then they were compared with the results using a 50 cm long, 100 μm diameter glass fiber. The Raman spectrum of each tested material becomes indistinguishable due to the background Raman signal of the glass fiber but can easily be seen using the sapphire fiber, which has only a few narrow Raman peaks of its own.     

基于自适应免疫算法重叠拉曼谱峰的解析

拉曼光谱测量速度快,可以实现原位实时测量,现已成为过程控制中物料检测的一种重要手段。但由于环境的复杂性以及拉曼光谱信号特点,目前在线检测时难免会出现一些重叠谱峰。基于免疫算法特点,将该方法用于芳烃重叠拉曼谱峰信号的解析中,提取混合物质中单个组分拉曼谱峰信息进行分析,结果表明该方法解析快速、定量准确,相对误差低于1%,是解析重叠拉曼光谱信号的有效方法。针对现场样品检测中出现的重叠谱峰伴随荧光背景信号,提出了结合独立成分分析的自适应免疫算法,有效地解析出荧光背景信号,为复杂样品的拉曼光谱检测分析提供了新的手段。     

用激光拉曼光谱区分胃癌变细胞与正常细胞

利用激光拉曼光谱对胃癌细胞及正常胃细胞进行了对比检测,对胃癌细胞特征拉曼峰作了初步探讨,发现胃癌患者标本的特征拉曼峰与非胃癌患者标本的光谱有明显的不同。实验发现,浓度为每mL 1.25×105个胃癌细胞的样品在经过若干天培养后均能够被检测出胃癌细胞的特征拉曼峰,分别位于特定波长583,633,656 nm处。这是几个很少见诸报道的新拉曼光谱峰。不论是特征拉 曼峰,还是在胃癌细胞及正常胃细胞的几个共有的拉曼峰674, 707, 773, 799 nm处,拉曼光谱强度都是随血清中癌细胞浓度的增加而增加。激光拉曼光谱分析有可能发展成为一种快速有效的癌细胞检测方 法。