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白藜芦醇负离子与Ag^+化合物的振动光谱研究 预览
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作者 金鹿 杨青青 +2 位作者 代明锁 何源 潘乐 《化学研究与应用》 CAS CSCD 北大核心 2019年第8期1441-1447,共7页
本研究采用密度泛函理论不仅对顺式和反式白藜芦醇的结构、IR和Raman光谱进行了计算模拟和分析指认,而且还考察了其负离子与Ag+结合后的结构和相应的光谱分析。研究结果表明:(1) Ag^+结合在白藜芦醇的单酚羟基位时,会大大提高拉曼活性;... 本研究采用密度泛函理论不仅对顺式和反式白藜芦醇的结构、IR和Raman光谱进行了计算模拟和分析指认,而且还考察了其负离子与Ag+结合后的结构和相应的光谱分析。研究结果表明:(1) Ag^+结合在白藜芦醇的单酚羟基位时,会大大提高拉曼活性;(2)可以通过连接两个酚的C=C的伸缩振动(1650 cm-1)的拉曼活性不同鉴别顺式和反式白藜芦醇的结构。这开启了一个新的观测窗口来探测白藜芦醇的顺反转变过程;(3)Ag^+结合白藜芦醇负离子后,与Ag相连的C-O伸缩振动的拉曼活性加强,从而可以据此来确定白藜芦醇负离子是否与Ag^+相结合;(4)通过谱峰的数目可以区别顺式和反式白藜芦醇负离子与Ag^+结合的结构。本研究结果不仅对采用光谱方法区分结构,而且对理解表面增强拉曼光谱(SERS)具有重要的意义。 展开更多
关键词 白藜芦醇 IR RAMAN 理论模拟 振动分析
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Dual-Wavelength Laser Flash Raman Spectroscopy Method for In-Situ Measurements of the Thermal Diffusivity: Principle and Experimental Verification
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作者 FAN Aoran HU Yudong +2 位作者 MA Weigang WANG Haidong ZHANG Xing 《热科学学报:英文版》 SCIE EI CAS CSCD 2019年第2期159-168,共10页
This paper presents an in-situ, non-contact, non-destructive 'dual-wavelength laser flash Raman spectroscopy method' for measuring the thermal diffusivity. In this method, a heating pulse is used to heat the s... This paper presents an in-situ, non-contact, non-destructive 'dual-wavelength laser flash Raman spectroscopy method' for measuring the thermal diffusivity. In this method, a heating pulse is used to heat the sample and another pulsed laser with a different wavelength and negligible heating effect is used as a probe to measure the sample temperature changes during the heating and cooling periods from the Raman peak shifts. The sample temperature rise and fall curves are measured by changing the delay between the heating pulse and the probing pulse with the thermal diffusivity then characterized by fitting the temperature curves. The time delay between the heating and probing pulses can be precisely controlled with a minimum step of 100 ps. Hence, the temperature variation can be scanned with an ultra-high temporal resolution of up to 100 ps, which significantly improves the measurement accuracy of transient thermal parameters. The measurement accuracy of this method has been verified using a bulk material model and experiments. The measured thermal diffusivity of a silicon sample has been obtained to be 8.8×10-5 m2/s with a 3% difference between the measured value and the average result for bulk silicon in the literature which verifies the reliability and accuracy of this method. 展开更多
关键词 DUAL-WAVELENGTH laser flash RAMAN SPECTROSCOPY METHOD thermal DIFFUSIVITY RAMAN SPECTROSCOPY nanomaterials bulk materials
Flexible and reusable cap-like thin Fe2O3 film for SERS applications
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作者 Jiangtao Xu Xiaoting Li +3 位作者 Yuxiang Wang Ronghui Guo Songmin Shang Shouxiang Jiang 《纳米研究:英文版》 SCIE EI CAS CSCD 2019年第2期381-388,共8页
Cap-like α-Fe2O3 films are fabricated and deposited onto quartz fabric by using radio frequency magnetron sputtering and annealing.The treated fabric sample in this study shows highly sensitive surface-enhanced Raman... Cap-like α-Fe2O3 films are fabricated and deposited onto quartz fabric by using radio frequency magnetron sputtering and annealing.The treated fabric sample in this study shows highly sensitive surface-enhanced Raman scattering (SERS) and excellent flexibility,reproducibility and stability.In addition,the sample can be recovered after a washing process with an organic solvent and repeatedly used.The sensitive SERS performance is attributed to chemical enhancement through a charge transfer process.Moreover,the SERS performance is also found to be dependent on the light coupling effect.When the light absorbance rate of the α-Fe2O3 films increases at a wavelength near that of laser light,the film shows excellent sensitivity due to light coupling effect. 展开更多
关键词 Α-FE2O3 QUARTZ fabric FLEXIBLE surface-enhanced RAMAN scattering (SERS) RAMAN sensor
SERS-based lateral flow immunoassay of troponin I by using gapenhanced Raman tags
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作者 Boris N. Khlebtsov Daniil N. Bratashov +2 位作者 Nadezhda A. Byzova Boris B. Dzantiev Nikolai G. Khlebtsov 《纳米研究:英文版》 SCIE EI CAS CSCD 2019年第2期413-420,共8页
The lateral flow immuno assay (LFIA) has emerged as a powerful tool for rapid scree ning owing to its simplicity and flexibility for detection of various biomarkers. However, conventional LFIA strips have several disa... The lateral flow immuno assay (LFIA) has emerged as a powerful tool for rapid scree ning owing to its simplicity and flexibility for detection of various biomarkers. However, conventional LFIA strips have several disadvantages, including limits in quantitative analysis and low sensitivity. Here we developed a novel surface-e nhanced Rama n scatteri ng LFIA based on non spherical gap-e nhanced Raman tags (GERTs), with Raman molecules (RMs) embedded in a 1-nm gap between Au nanorod core and Au shell. Such tags have a strong and uniform surface-enhanced Rama n scattering (SERS) resp on se, an order of mag nitude higher than that of other comm on SERS tags such as Au nano rods, nano stars, Au nano shells with surface-adsorbed RMs, or spherical GERTs with embedded RMs. The feasibility of the tags was dem on strated by the semiqua ntitative and sen sitive detecti on of the heart disease biomarker cardiac tropo nin I (cTnI). GERTs were conjugated with mono clonal antibodies and used for LFIA in the same way as ordinary functionalized colloidal gold. The presenee of the target antigen, cTnI, was identified by Raman microscopy mapping of the test zone. With the SERS-based LFIA, the limit of cTnI detection was about 0.1 ng/mL. This value is within the diagnostic range of cTnI in the blood serum of patients with heart infarction and is 30 times lower than that of the colorimetric LFIA test using the same antibodies and either GERTs or colloidal gold as labels. 展开更多
关键词 surface-enhanced RAMAN scattering (SERS) lateral flow IMMUNOASSAY Au core/shell NANORODS gap-enhanced RAMAN tags CARDIAC TROPONIN I
P 2O 5对Na 2O-Al 2O 3-SiO 2系统玻璃结构和分相的影响 预览
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作者 昝昱廷 陆平 牛韵雅 《硅酸盐通报》 CAS 北大核心 2019年第8期2492-2496,2505,共6页
通过制备25Na2O-(25-x)Al2O3-50SiO2-xP2O5(x≤25mol%)系统玻璃,并且采用Raman和SEM,研究了高含量P2O5对Na2O-Al2O3-SiO2系统玻璃结构和分相的影响。结果表明:随着P2O5的不断加入,作为电价平衡体的Na+被逐渐释放,并且充当了网络改变体... 通过制备25Na2O-(25-x)Al2O3-50SiO2-xP2O5(x≤25mol%)系统玻璃,并且采用Raman和SEM,研究了高含量P2O5对Na2O-Al2O3-SiO2系统玻璃结构和分相的影响。结果表明:随着P2O5的不断加入,作为电价平衡体的Na+被逐渐释放,并且充当了网络改变体的角色,造成了硅酸盐网络结构聚合度降低,而磷酸盐网络结构聚合度增大。随着P2O5的不断加入且Al/P<1时,该系统玻璃发生稳定分相,而且分相机理也由成核-生长转变为亚稳分解。 展开更多
关键词 Na2O-Al2O3-SiO2-P2O5系统玻璃 玻璃结构 RAMAN 分相机理
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First-Stokes Wavelengths at 1175.8 and 1177.1nm Generated in a Diode End-Pumped Nd:YVO4/LuVO4 Raman Laser
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作者 周青青 施沈城 +5 位作者 陈思梦 段延敏 张喜梅 郭锦 赵斌 朱海永 《中国物理快报:英文版》 SCIE CAS CSCD 2019年第1期32-35,共4页
A diode end-pumped acousto-optic Q-switched Nd:YVO4/LuVO4 Raman laser is demonstrated.Both YV04 and LuVO4 can work as Raman gain,and slightly different active vibration modes of both crystals can result in different f... A diode end-pumped acousto-optic Q-switched Nd:YVO4/LuVO4 Raman laser is demonstrated.Both YV04 and LuVO4 can work as Raman gain,and slightly different active vibration modes of both crystals can result in different flrst-Stokes wavelengths.The output characteristic as the Raman competition between YVO4 and LuVO4 crystals dor the laser systems with both shared cavity and coupled cavity is experimentally investigated. For the shared cavity,simultaneous Raman conversion in both YVO4 and LuVO4 crystals is achieved with dualwavelength emission at 1175.8 and 1177.1 nm.The maximum output power of 1.03 Wand the conversion efficiency of 10.3% are obtained.The 0.84 W single first Stokes wavelength at 1177.1 nm with LuV04 Raman conversion is achieved with the coupled cavity.The results show that the coupled cavity with short Raman cavity can obtain a narrow pulse width.The separated laser crystal and Raman gain media with different vanadates in shared cavity have advantages in achieving dual-wavelength lasers with small frequency intervals. 展开更多
关键词 Tox WAVELENGTH DIODE side PUMP Raman laser
One step synthesis of high efficiency nickel/mesoporous TiO2 hybrid catalyst for hydrogen evolution reaction 预览
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作者 Esteban A.Franceschini Melisa J.Gomez Gabriela I.Lacconi 《能源化学:英文版》 SCIE EI CAS CSCD 2019年第2期79-87,共9页
Nickel-Ti O2 hybrid catalysts are synthesized by electrodeposition and their catalytic activity with respect to the hydrogen evolution reaction is analyzed.Two types of titanium oxide particles,which are commercial pa... Nickel-Ti O2 hybrid catalysts are synthesized by electrodeposition and their catalytic activity with respect to the hydrogen evolution reaction is analyzed.Two types of titanium oxide particles,which are commercial particles of dense Ti O2 and mesoporous TiO2 particles synthesized by an aerosol method,are incorporated into the matrix of the nickel catalyst.Both nickel catalysts containing Ti O2 particles presented higher catalytic activity than the conventional nickel Watts catalyst.Mesoporous TiO2-modified nickel catalyst showed the highest catalytic activity towards HER in alkaline medium.In addition,this type of nickel catalyst increases its catalytic activity after ageing treatment,which is an indication of an increase in the electro-active area of the electrode. 展开更多
关键词 CO-DEPOSITION IMPEDANCE SPECTROSCOPY TITANIUM OXIDE Ageing process RAMAN SPECTROSCOPY
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Mass-production of flexible and transparent Te-Au nylon SERS substrate with excellent mechanical stability
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作者 Wei-Ran Huang Cheng-Xin Yu +4 位作者 Yi-Ruo Lu Hassan Muhammad Jin-Long Wang Jian-Wei Liu Shu-Hong Yu 《纳米研究:英文版》 SCIE EI CAS CSCD 2019年第6期1483-1488,共6页
In the past two decades,the field of surface-enhanced Raman scattering (SERS) has flourished and many rational strategies have been reported for the successful construction of SERS substrates.However,it still lacks th... In the past two decades,the field of surface-enhanced Raman scattering (SERS) has flourished and many rational strategies have been reported for the successful construction of SERS substrates.However,it still lacks the mass-production and programmability for practical applications with arbitrary configurations,and it is highly desirable to develop SERS substrates with strong signal enhancement,large-scale surface area,easy fabrication and low cost.Herein,we demonstrate a large-area fabrication (1.5 m × 5 m) of low-cost (18.8 dollars per square meter),highly sensitive,flexible and transparent SERS substrate by a simple solution process.The high sensitivity of SERS substrate using 3,3'-diethylthiatricarbocyanine iodide (DTTCI) as probe molecules is strongly dependent on the density and diameter of gold nanoparticles (NPs) on the surface of nylon mesh with the best enhancement factor (EF) of 9.17 × 10^10 and the SERS detection limit of DTTCI molecules is as low as 10-14 M which shows no obvious degradation even after 10,000 cycles of fatigue test,high temperature (above than 160 ℃) and acid-alkali treatment,indicating their excellent stability for the performance in all climates. 展开更多
关键词 MASS-PRODUCTION FLEXIBLE TRANSPARENT surface-enhanced Raman scattering gold nanoparticles
Plasma-enabled healing of graphene nano-platelets layer
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作者 Xiuqi Fang Carles Corbella +1 位作者 Denis B.Zolotukhin Michael Keidar 《化学科学与工程前沿:英文版》 EI CAS CSCD 2019年第2期350-359,共10页
Graphene platelet networks (GPNs) were deposited onto silicon substrates by means of anodic arc discharge ignited between two graphite electrodes.Substrate temperature and pressure of helium atmosphere were optimized ... Graphene platelet networks (GPNs) were deposited onto silicon substrates by means of anodic arc discharge ignited between two graphite electrodes.Substrate temperature and pressure of helium atmosphere were optimized for the production of the carbon nanomaterials.The samples were modified or destroyed with different methods to mimic typical environments responsible of severe surface degradation.The emulated conditions were performed by four surface treatments,namely thermal oxidation,substrate overheating,exposition to glow discharge,and metal coating due to arc plasma.In the next step,the samples were regenerated on the same substrates with identical deposition technique.Damaging and re-growth of GPN samples were systematically characterized by scanning electron microscopy and Raman spectroscopy.The full regeneration of the structural and morphological properties of the samples has proven that this healing method by arc plasma is adequate for restoring the functionality of2D nanostructures exposed to harsh environments. 展开更多
关键词 GRAPHENE PLATELET networks anodic arc discharge PLASMA HEALING scanning electron MICROSCOPY Raman spectroscopy
不同干燥方式下沙丁鱼干燥特性的比较 预览
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作者 蔡路昀 台瑞瑞 +5 位作者 周小敏 曹爱玲 关荣发 王彦波 赵元晖 励建荣 《食品工业科技》 CAS 北大核心 2019年第6期19-25,共7页
为了研究不同干燥方式对沙丁鱼干燥特性的影响,采取冷风、热风、微波真空、冷风-微波真空和热风-微波真空5种干燥方式对沙丁鱼进行处理,研究不同干燥方式对沙丁鱼色泽、质构、水分变化、微观结构和干燥后对蛋白质二级结构的影响。结果表... 为了研究不同干燥方式对沙丁鱼干燥特性的影响,采取冷风、热风、微波真空、冷风-微波真空和热风-微波真空5种干燥方式对沙丁鱼进行处理,研究不同干燥方式对沙丁鱼色泽、质构、水分变化、微观结构和干燥后对蛋白质二级结构的影响。结果表明,不同干燥方式对干制鱼肉色泽影响差异显著(p <0.05),微波真空干燥有助于提高鱼肉的亮度,并与鲜肉最为接近,冷风-微波真空在色度方面表现良好;不同干燥方式对质构影响显著(p <0.05),干燥方式中,微波真空干燥方式有降低硬度、咀嚼度;微观结构中热风和冷风处理后的肌肉纤维紧密,冷风-微波真空处理后的肌肉呈现疏松且密集的网状;干燥使得不易流动水大量流失,水分发生迁移,微波真空与热风-微波真空、冷风-微波真空干燥使肌肉纤维疏松;同时,干燥破坏了蛋白质二级结构,使得α-螺旋向β-折叠、无规则卷曲转化,冷风干燥对其二级结构的影响程度最小,结果为沙丁鱼的生产加工提供理论依据。 展开更多
关键词 干燥方式 沙丁鱼 微观结构 拉曼
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荧光褪色效应与拉曼光谱基线干扰消除 预览
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作者 姚志湘 粟晖 +3 位作者 韩莹 徐记各 黄晓程 忻欣 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 2019年第7期2034-2039,共6页
荧光是直接测定的拉曼光谱中背景的最主要来源,需要采用真实、准确的方法消除,以得到纯净的拉曼响应。基线拟合消除和查找荧光贡献扣除是解决背景问题的两条思路,目前多采用基线拟合方法,其优点是满足用户“视觉”要求,无需额外硬件,但... 荧光是直接测定的拉曼光谱中背景的最主要来源,需要采用真实、准确的方法消除,以得到纯净的拉曼响应。基线拟合消除和查找荧光贡献扣除是解决背景问题的两条思路,目前多采用基线拟合方法,其优点是满足用户“视觉”要求,无需额外硬件,但并非机理或实质上的解释,因而难以保证数据的真实性与合理性;查找荧光的方法,更为真实,但是目前提出的方法,需要增加光源等额外设计和成本。另外,在实验方法上,也有采用消荧光剂和长时间照射漂白的,存在操作繁琐、效率低等不足。利用稳定体系中拉曼和荧光的时间差异解决体系中荧光问题。在微小的时间段内,例如几个毫秒,激发光不会导致体系性质发生显著变化,荧光具有寿命周期,会随激发时间延长强度下降的“褪色”,“褪色”的强度差异可以被认为是整体荧光的一个微元;与此同时,由于体系组成未发生显著变化,拉曼光对于短时间照射可以保持稳定。利用此差异可以区分出混合信号中的荧光和拉曼光。根据该原理,提出了荧光褪色差分法(FBDA),实现拉曼光谱的背景校正。方法的主要步骤:测量微小时刻内的多张直接拉曼光谱,求取系列光谱的差分,对差分值作高频滤波降噪,可获得荧光强度微元;然后,多个荧光微元平均归一化后,得到荧光强度单元。以拉曼光谱2000~2500cm^-1的静默区,即通常不会出现拉曼信号的频段为基准,对荧光单元作逆差分,逆差分累计值与原始光谱在此频段一致时,得到整体荧光响应;最终,从原始光谱中扣除荧光成分,完成背景扣除和基线校正。以盐酸二甲双胍片的拉曼测量为例,说明和讲解了所提出的原理和方法,验证方法的有效性。与目前效果较好的基线校正方法(不对称最小二乘和自适应迭代再加权惩罚偏最小二乘)进行了对比,表明FBDA方法更为客观真实,FBDA的另一个优势是不� 展开更多
关键词 拉曼 荧光 光褪色 差分 降噪
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High Power Linearly Polarized Raman Fiber Laser With Stable Temporal Output
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作者 Jiaxin SONG Hanshuo WU +3 位作者 Jun YE Jiangming XU Hanwei ZHANG Pu ZHOU 《光子传感器:英文版》 EI CAS CSCD 2019年第1期43-48,共6页
We demonstrate a high power linearly polarized Raman fiber laser(RFL)pumped by an amplified spontaneous emission(ASE)source.Temporal-stable operation of RFL could be ensured owing to the employment of ASE,which mitiga... We demonstrate a high power linearly polarized Raman fiber laser(RFL)pumped by an amplified spontaneous emission(ASE)source.Temporal-stable operation of RFL could be ensured owing to the employment of ASE,which mitigates the inherent intensity noise compared with the classic scheme adopting laser oscillator as pump source.In this experiment,the RFL has up to 119.5W output power,with central wavelength of 1129.2nm,and full width at half maximum(FWHM)linewidth of about 4.18nm.The polarization extinction ratio(PER)of the Raman laser is about 23dB.Moreover,this laser has excellent long-term and short-term stabilities in terms of the output power and time domain. 展开更多
关键词 RAMAN fiber laser amplified SPONTANEOUS emission LINEARLY polarized
High-brightness all-fiber Raman lasers directly pumped by multimode laser diodes
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作者 S.A.Babin 《高功率激光科学与工程:英文版》 CAS CSCD 2019年第1期107-113,共7页
High-brightness fiber laser sources usually utilize active rare-earth-doped fibers cladding-pumped by multimode laser diodes(LDs),but they operate in limited wavelength ranges.Singlemode-passive-fiber based Raman lase... High-brightness fiber laser sources usually utilize active rare-earth-doped fibers cladding-pumped by multimode laser diodes(LDs),but they operate in limited wavelength ranges.Singlemode-passive-fiber based Raman lasers are able to operate at almost any wavelength being pumped by high-power fiber lasers.One of the interesting possibilities is to directly pump graded-index(GRIN)multimode passive fibers by available high-power multimode LDs at 915-940 nm,thus achieving high-power Raman lasing in the wavelength range of 950-1000 nm,which is problematic for rare-earthdoped fiber lasers.Here we review the latest results on the development of all-fiber high-brightness LD-pumped sources based on GRIN fiber with in-fiber Bragg gratings(FBGs).The mode-selection properties of FBGs inscribed by fs pulses supported by the Raman clean-up effect result in efficient conversion of multimode pump into a high-quality output beam at 9xx nm.GRIN fibers with core diameters 62.5,85 and 100μm are compared.Further scaling capabilities and potential applications of such sources are discussed. 展开更多
关键词 beam cleaning fiber LASER high BRIGHTNESS LASER diode pumping Raman LASER
菜籽油经煎炸处理结构变化分析及机理探究 预览
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作者 赵云龙 周中凯 《粮食与油脂》 北大核心 2019年第8期43-45,共3页
以原始样品(0d样品)与煎炸处理5d菜籽油样品(5d样品)为原料,通过傅里叶变换中红外(FT-MIR)、傅里叶变换近红外(FT-NIR)和拉曼(Raman)仪检测,探究煎炸处理对菜籽油结构变化的影响。主要探究2个菜籽油样品官能团极性和非极性化学键的变化... 以原始样品(0d样品)与煎炸处理5d菜籽油样品(5d样品)为原料,通过傅里叶变换中红外(FT-MIR)、傅里叶变换近红外(FT-NIR)和拉曼(Raman)仪检测,探究煎炸处理对菜籽油结构变化的影响。主要探究2个菜籽油样品官能团极性和非极性化学键的变化情况,以期从本质上揭示煎炸处理对菜籽油结构变化的影响,并为油脂产品热稳态研究及储存期保藏提供一定的科学依据。 展开更多
关键词 煎炸处理 红外 拉曼 结构变化 热稳态
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Applications of magnetic nanoparticles in surface-enhanced Raman scattering(SERS)detection of environmental pollutants
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作者 Dan Song Rong Yang +1 位作者 Feng Long Anna Zhu 《环境科学学报:英文版》 SCIE EI CAS CSCD 2019年第6期14-34,共21页
Environmental pollution, a major problem worldwide, poses considerable threat to human health and ecological environment. Efficient and reliable detection technologies, which focus on the appearance of emerging enviro... Environmental pollution, a major problem worldwide, poses considerable threat to human health and ecological environment. Efficient and reliable detection technologies, which focus on the appearance of emerging environmental and trace pollutants, are urgently needed. Surface-enhanced Raman scattering(SERS) has become an attractive analytical tool for sensing trace targets in environmental field because of its inherent molecular fingerprint specificity and high sensitivity. In this review, we focused on the recent developments in the integration of magnetic nanoparticles(MNPs) with SERS for facilitating sensitive detection of environmental pollutants. An overview and classification of different types of MNPs for SERS detection were initially provided, enabling us to categorize the huge amount of literature that was available in the interdisciplinary research field of MNPs based SERS technology. Then, the basic working principles and applications of MNPs in SERS detection were presented. Subsequently, the detection technologies integrating MNPs with SERS that eventually were used for the detection of various environmental pollutions were reviewed. Finally, the advantages of MNP-basedSERS detection technology for environmental pollutants were concluded, and the current challenges and future outlook of this technology in practical applications were highlighted. The application of the MNPsbasedSERS techniques for environmental analysis will be significantly advanced with the great progresses of the nanotechnologies, optics, and materials. 展开更多
关键词 Magnetic nanoparticles Surface-enhanced RAMAN SCATTERING SERS SUBSTRATES Environmental POLLUTANT DETECTION
1.56μm and 2.86μm Raman lasers based on gas-filled anti-resonance hollow-core fiber
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作者 黄威 崔宇龙 +2 位作者 李智贤 周智越 王泽锋 《中国光学快报:英文版》 SCIE EI CAS CSCD 2019年第7期66-70,共5页
We report here a single-pass 1.56 μm fiber gas Raman laser in a deuterium-filled hollow-core fiber and a 2.86 μm cascade fiber gas Raman laser with methane in the second stage.The maximum output powers at 1.56 and 2... We report here a single-pass 1.56 μm fiber gas Raman laser in a deuterium-filled hollow-core fiber and a 2.86 μm cascade fiber gas Raman laser with methane in the second stage.The maximum output powers at 1.56 and 2.86 μm are 27 and 8.5 m W with Raman conversion efficiency of 30% and 42%, respectively.The results offer a new method to produce a 1.5 μm fiber source and prove the potential of the cascade fiber gas Raman laser in extending the available wavelength. 展开更多
关键词 RAMAN CASCADE GAS
拉曼光谱对电极材料和电解液的表征 预览
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作者 罗瑞 张峥 《电源技术》 CAS 北大核心 2019年第2期223-226,共4页
锂离子电池由于具有高的输出电压和高的比能量而在商品化电池中脱颖而出,所以研究锂离子电池电极材料的组成与分子结构,研究电池充放电过程中它的组成、分子结构的变化,对进一步优化正负极材料的性能有着重要的指导意义。而拉曼光谱对... 锂离子电池由于具有高的输出电压和高的比能量而在商品化电池中脱颖而出,所以研究锂离子电池电极材料的组成与分子结构,研究电池充放电过程中它的组成、分子结构的变化,对进一步优化正负极材料的性能有着重要的指导意义。而拉曼光谱对锂离子电池正负极材料及电解质都可进行识别及表征,成为分析电极材料最有力的工具。 展开更多
关键词 锂离子电池 正极材料 拉曼光谱 负极材料
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Probing interlayer interactions in WSe2-graphene heterostructures by ultralow-frequency Raman spectroscopy
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作者 刘月 周煜 +7 位作者 张昊 冉飞荣 赵炜昊 王琳 裴成杰 张锦东 黄晓 李海 《物理学前沿:英文版》 SCIE CSCD 2019年第1期59-66,共8页
Interlayer interactions at the heterointerfaces of van der Waals heterostructures (vdWHs), which consist of vertically stacked two-dimensional materials, play important roles in determining their properties. The inter... Interlayer interactions at the heterointerfaces of van der Waals heterostructures (vdWHs), which consist of vertically stacked two-dimensional materials, play important roles in determining their properties. The interlayer interactions are tunable from noncoupling to strong coupling by controlling the twist angle between adjacent layers. However, the influence of stacking sequence and individual component thickness on the properties of vdWHs has rarely been explored. In this work, the influence of the stacking sequence of WSe2 and graphene in vdWHs of graphene-on-WSe2 (graphene/WSe2) or WSe2-on-graphene (WSe2/graphene), as well as their thickness, on their interlayer interaction was systematically investigated by ultralow-frequency (ULF) Raman spectroscopy. A series of ULF breathing modes of WSe2 nanosheets in these vdWHs were observed with frequencies highly dependent on graphene thickness. Interestingly, the ULF breathing modes of WSe2 red-shifted in graphene/WSe2 and WSe2/graphene configurations, and the amount of shift in the former was much larger than that in the latter. In contrast, no obvious ULF shift was observed by varying the twist angle between WSe2 and graphene. This indicates that the interlayer interaction is more sensitive to the stacking sequence compared with the twist angle. The results provide alternative approaches to modulate the interlayer interaction of vdWHs and, thus, tune their optical and optoelectronic properties. 展开更多
关键词 INTERLAYER interaction van der WAALS HETEROSTRUCTURES two-dimensional materials stacking sequence ultralow-frequency Raman breathing mode
Stacking transition in rhombohedral graphite
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作者 Tataiana Latychevskaia Seok-Kyun Son +8 位作者 Yaping Yang Dale Chancellor Michael Brown Servet Ozdemir Ivan Madan Gabriele Berruto Fabrizio Carbone Artem Mishchenko Kostya S. Novoselov 《物理学前沿:英文版》 SCIE CSCD 2019年第1期67-73,共7页
Few-layer graphene (FLG) has recently been intensively investigated for its variable electronic properties, which are defined by a local atomic arrangement. While the most natural arrangement of layers in FLG is ABA (... Few-layer graphene (FLG) has recently been intensively investigated for its variable electronic properties, which are defined by a local atomic arrangement. While the most natural arrangement of layers in FLG is ABA (Bernal) stacking, a metastable ABC (rhombohedral) stacking, characterized by a relatively high-energy barrier, can also occur. When both types of stacking occur in one FLG device, the arrangement results in an in-plane heterostructure with a domain wall (DW). In this paper, we present two approaches to demonstrate that the ABC stacking in FLG can be controllably and locally turned into the ABA stacking. In the first approach, we introduced Joule heating, and the transition was characterized by 2D peak Raman spectra at a submicron spatial resolution. The transition was initiated in a small region, and then the DW was controllably shifted until the entire device became ABA stacked. In the second approach, the transition was achieved by illuminating the ABC region with a train of 790-nm-wavelength laser pulses, and the transition was visualized by transmission electron microscopy in both diffraction and dark-field imaging modes. Further, using this approach, the DW was visualized at a nanoscale spatial resolution in the dark-field imaging mode. 展开更多
关键词 graphene GRAPHITE van der WAALS HETEROSTRUCTURES domain wall Raman spectroscopy transmission ELECTRON microscopy ELECTRON diffraction structural TRANSITION
Spectroscopic study of conformation changes of bovine serum albumin in aqueous environment
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作者 Chune Guo Xiaomi Guo +2 位作者 Wubo Chu Nan Jiang He Li 《中国化学快报:英文版》 SCIE CAS CSCD 2019年第6期1302-1306,共5页
The secondary structural changes of bovine serum albumin (BSA) aqueous solutions with and without calcium cations were investigated by attenuated total reflection-Fourier transform infrared (ATR-FTIR) technology. The ... The secondary structural changes of bovine serum albumin (BSA) aqueous solutions with and without calcium cations were investigated by attenuated total reflection-Fourier transform infrared (ATR-FTIR) technology. The spectra of BSA solution and BSA dry powder were mainly reflected the formation of hydrogen bonds between water and BSA. Further investigation indicated that the concentrations of calcium cations in BSA aqueous solution also affected the secondary structural change of the protein. Amide I band was red shifted and amide II band was blue shifted in aqueous environment compared with the dry BSA powder, and the addition of calcium cations further changed the amide bands position, which led to the change of the secondary structure. The result was coinciding with the Raman spectroscopy. 展开更多
关键词 BSA Secondary structure change Calcium CATION ATR-FTIR RAMAN
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