原位拉曼光谱定量探测深海高温热液喷口流体获新突破

正近日,中国科学院海洋大科学研究中心研究员阎军团队和李超伦团队在深海热液系统原位拉曼光谱定量探测研究中获得进展。基于自主研发的深海原位激光拉曼光谱探测系统(Raman insertion probe-RiP)对冲绳海槽中部热液区的高温热液流体进行了原位拉曼光谱定量探测,在国际上首次获得高温热液流体中溶解二氧化碳及硫酸根离子的原位浓度。相关研究成果以封面论文的形式,发表     

深海潜标系统电池舱的设计与分析

针对深海潜标系统观测仪器,设计了一种径高比满足黄金分割比的电池舱.按照压力容器设计准则,对这一深海潜标系统电池舱进行了选材、强度计算和稳定性校核,应用Workbench有限元软件对电池舱的强度和稳定性进行了模拟分析,确认电池舱满足水下承压20 MPa的要求.应用这一电池舱,可以使深海潜标系统观测仪器具备长时间工作的能力.     

进样泵在海水气体水下气相色谱原位测试系统中应用

海水中的标志性气体是追索海洋物理、化学和生物过程变化的有效示踪剂。水下气相色谱原位气体测试系统有望成为一种有效的深海气体原位检测技术,能在水下对深海中的多种溶解性气体进行准确的原位检测。进样泵是水下气相色谱原位气体测试系统的一个重要部件,阐述了进样泵耐压壳体的计算模型,仿真分析了压力储备对不同布放深度下壁厚的影响。     

深海高压模拟舱的设计

深海高压模拟舱为深海装备检测而研制,最大工作直径1500 mm,可模拟3500 m深海高压环境,检验水下设备在高压下的强度和密封性能,用于质量检验和产品研发。高压模拟舱按照疲劳容器设计,采用"O型圈径向密封+分瓣式卡箍"结构,能够实现快速启闭。试验表明,文中研制的高压模拟舱密封可靠、操作性能良好,可为其它各类高压模拟舱的设计提供一定的设计依据。     

深海原位激光扫描双目立体视觉成像系统

为满足深海物体原位三维测量需要,提出一种激光扫描双目立体视觉成像方法。该方法基于双目立体视觉原理,采用四维光场光线表示法,建立水下双目立体成像系统的测量模型;采用激光线扫描光条作为像素匹配线索,及基于共面约束的像素匹配算法,提高水下左、右两个相机图像像素匹配精度。通过耐高压结构设计、电气和软件设计,建立起相应的工程样机。静水压力试验表明,该工程样机能够适应4 000 m深海静水压力;实验室精度试验,采用标准球棒为测量对象,在距离样机3 m处,多次扫描三维重建后,得到两靶球球心距测量结果的标准差为2.28 mm;南海真实海域实测试验,表明样机具有深海原位三维测量重建功能,且在距离样机2 m处,对标准球棒两球心距测量结果的标准差为2.22 mm。上述研究和试验表明,研制的激光扫描双目立体视觉成像系统,具备深海原位测量功能,具有较高三维测量精度。     

深海耐压舱结构优化选型设计

通过对深海水下无人潜航器的使用环境进行分析,设计了两种不同结构形式的深海耐压舱,建立了耐压舱的有限元模型,并对两种结构形式的耐压舱分别进行了强度和稳定性分析对比,结合耐压舱段质量和浮力的计算,最终选择合适的耐压舱结构,并进行了打压试验验证了设计的可行性。     

用于原位状态下的激光拉曼光谱测试系统的研制

本文介绍了一种适合于表面结构研究的激光拉曼光谱原位测试系统,此系统由二个主要部分组成。其一是旋转光束装置,用于避免和减少激光束对所测样品表面的损伤.其二是原位石英拉曼样品池,它可以与气体处理系统连接,对样品进行原位的氧化,还原,反应及抽空等处理.本系统的突出特点是,在改善拉曼谱信噪比的同时,可进行真实状态下的各种原位激光拉曼光谱研究.     

一种模块化水下机器人的设计

介绍了一种模块化设计的水下机器人。按各功能模块将水下机器人分为探测识别舱段、动力推进舱段、控制舱段和艉部去流舱段。并具体对每个舱段的设计作了分析。经试验表明,机器人能较好地完成水下作业任务。     

水下捕捞机器人耐压舱仿生造型设计

为降低捕捞作业的运行成本,对水下捕捞机器人的耐压舱进行仿生减阻设计。以粒突箱鲀为仿生对象,基于灰度转换和边缘检测技术提取其外形特征廓线,以捕捞机器人特征高度为设计变量建立仿生耐压舱三维模型,并将回转体耐压舱模型作为对比对象,通过Fluent软件对两种耐压舱进行流体仿真分析,分别比较其阻力系数、阻力和升力系数。结果表明：与传统回转体耐压舱相比,仿生耐压舱具有更小的阻力系数,可有效减小其在水中行进的阻力;仿生耐压舱的流线型结构有效降低了流场扰动,提高了捕捞机器人在水下运行时的平稳性。研究结果可为水下捕捞机器人耐压舱的造型仿生及减阻设计提供理论依据。     

基于远程拉曼光谱的物质检测研究

设计和建立轻型远程拉曼光谱探测系统,通过时域脉冲的发射源和数字延时电路实现拉曼信号同步采集,同时采用入瞳口径为50mm的伽利略望远光路增强拉曼信号的收集效率,并对易爆物质进行3m距离检测为例进行研究。其结果显示,系统具有非常高的信噪比、高分辨锐利的特征峰和快速检测能力,能应用于危险环境的识别和预警等方面。     

Portable fiber sensors based on surface-enhanced Raman scattering

Two portable molecular sensing systems based on surface-enhanced Raman scattering (SERS) have been experimentally demonstrated using either a tip-coated multimode fiber (TCMMF) or a liquid core photonic crystal fiber (LCPCF) as the SERS probe. With Rhodamine 6G as a test molecule, the TCMMF-portable SERS system achieved 2-3 times better sensitivity than direct sampling (focusing the laser light directly into the sample without the fiber probe), and a highly sensitive LCPCF-portable SERS system reached a sensitivity up to 59 times that of direct sampling, comparable to the sensitivity enhancement achieved using fiber probes in the bulky Renishaw system. These fiber SERS probes integrated with a portable Raman spectrometer provide a promising scheme for a compact and flexible molecular sensing system with high sensitivity and portability.     

过渡金属二硫化物拉曼散射在免疫检测中的应用

为了利用可见光激发下半导体拉曼散射信号实现生物检测,以窄带隙的MoS_2材料构建了拉曼免疫标记探针,用于实现对人IgG分子的高特异性识别。首先,运用液相剥离法分别获得了MoS_2和WS_2微米材料,以加热陈化处理分析了温度对532nm激发下样品拉曼散射信号强度的影响。之后借助3-巯基丙酸修饰向MoS_2材料表面引入羧基,进而获得了可用于免疫检测的拉曼探针。最后,以"抗体-待测物-抗体"的三层结构分析了基于MoS_2拉曼散射的免疫检测性能。实验发现适当温度下加热陈化处理可增强过渡金属二硫化物的拉曼散射强度(70℃下最优)。多组对照实验结果表明,免疫检测生物芯片的拉曼信号强度随人IgG浓度的升高而升高,最终趋于饱和,最低浓度的检测限达到1fM,实现了可见光激发下利用半导体拉曼散射信号对目标分子的高灵敏度、高特异性免疫检测。     

Evaluation of a femtosecond fiber laser for two-photon fluorescence correlation spectroscopy

This work evaluates a femtosecond fiber laser for use in two-photon fluorescence fluctuation spectroscopy. Fiber lasers present an attractive alternative to Ti:Sapphire systems because of their compact size and portability. Autocorrelation of the second harmonic generation signal from the laser demonstrates that its stability is sufficient for two-photon fluorescence correlation spectroscopy. Fluorescence correlation spectroscopy autocorrelation traces were well fit by a Gaussian-Lorentzian squared model with a beam waist near the diffraction limit for the 810 nm wavelength. A photon counting histogram collected with this system also fit nicely to a single-species model, further demonstrating the quality of the focal shape. The authors conclude that the output from the femtosecond fiber laser is sufficiently stable and has a high enough quality beam shape for fluctuation fluorescence methods, and thus represents an effective, compact, readily portable two-photon excitation source.     

Micro-Raman analysis of stress in machined silicon and germanium

Residual strain in single point diamond machined crystalline silicon and germanium has been measured with high spatial resolution (≈ 2 μm) using Raman microprobe spectroscopy. Raman spectroscopy is a direct, non-destructive technique which provides a spatial resolution down to the excitation wavelength and which may be applied to a wide range of non-conducting materials. Raman scattering was used to measure local strain at various points across single point plunge and feed cuts in crystalline silicon and germanium. Spectra were obtained using various excitation wavelengths (514.5 and 488.0 nm), which, due to their differing penetration lengths in the various materials, can provide depth profiles of the residual stress down to approximately 1 μm. In single point plunge cuts little evidence of surface damage was seen and the residual stresses are compressive. Using a 514.5 nm excitation wavelength, we measure a compressive stress of 250 MPa (2.5 kbar) near the outer edge of a single point plunge cut in silicon. At this wavelength, the penetration depth of the laser is 1.0 × 10⁻⁴ cm. This compressive stress was observed to increase to 600 MPa (6.0 kbar) at a depth of 0.6 × 10⁻⁴ cm which was measured using a 488.0 nm excitation wavelength. In single point feed cuts, regions of heavy fracturing were observed as well as regions of little visible damage. In damaged areas tensile stresses of 200–300 MPa (2.0–3.0 kbar) were measured in silicon while in germanium the tensile stress in such regions is 50–100 MPa (0.5–1.0 kbar). In undamaged areas the stresses are compressive with measured values of 50 and 30 MPa (0.5 and 0.3 kbar) for silicon and germanium respectively.     

注入锁定腔增强拉曼光谱微量气体检测技术

为了提高微量气体的拉曼散射强度,本文设计并搭建了注入锁定腔增强拉曼光谱微量气体检测平台。半导体激光器(波长为638nm,功率为15mW)输出到由三块高反镜组成的V型增强腔中,结合注入锁定技术,腔内激光强度达到7.5 W,实现了500倍的增强效果。利用该实验平台对微量单一气体及其混合气体进行了拉曼检测,并根据拉曼特征谱峰选取原则及信噪比大于3的原则,确定了H2、CO、CO2、CH4、C2H6、C2H4、C2H2的特征拉曼谱峰分别为4 156,2 143,1 388,2 918,2 955,1 344,1 975cm-1,最小检测极限分别为10.2,21.7,9.4,2.1,8.9,4.9,3.3Pa。腔增强拉曼光谱法可以实现微量同核双原子气体检测及利用单一波长激光的混合气体同时检测,具有替代气体检测传统光谱方法的潜力。     

Femtosecond broadband stimulated Raman spectroscopy: Apparatus and methods

The laser, detection system, and methods that enable femtosecond broadband stimulated Raman spectroscopy (FSRS) are presented in detail. FSRS is a unique tool for obtaining high time resolution (<100 fs) vibrational spectra with an instrument response limited frequency resolution of <10 cm(-1). A titanium:Sapphire-based laser system produces the three different pulses needed for FSRS: (1) A femtosecond visible actinic pump that initiates the photochemistry, (2) a narrow bandwidth picosecond Raman pump that provides the energy reservoir for amplification of the probe, and (3) a femtosecond continuum probe that is amplified at Raman resonances shifted from the Raman pump. The dependence of the stimulated Raman signal on experimental parameters is explored, demonstrating the expected exponential increase in Raman intensity with concentration, pathlength, and Raman pump power. Raman spectra collected under different electronic resonance conditions using highly fluorescent samples highlight the fluorescence rejection capabilities of FSRS. Data are also presented illustrating our ability: (i) To obtain spectra when there is a large transient absorption change by using a shifted excitation difference technique and (ii) to obtain high time resolution vibrational spectra of transient electronic states.     

Development of high-repetition-rate laser pump/x-ray probe methodologies for synchrotron facilities

We describe our implementation of a high repetition rate (54 kHz-6.5 MHz), high power (>10 W), laser system at the 7ID beamline at the Advanced Photon Source for laser pump/x-ray probe studies of optically driven molecular processes. Laser pulses at 1.06 μm wavelength and variable duration (10 or 130 ps) are synchronized to the storage ring rf signal to a precision of ~250 fs rms. Frequency doubling and tripling of the laser radiation using nonlinear optical techniques have been applied to generate 532 and 355 nm light. We demonstrate that by combining a microfocused x-ray probe with focused optical laser radiation the requisite fluence (with <10 μJ/pulse) for efficient optical excitation can be readily achieved with a compact and commercial laser system at megahertz repetition rates. We present results showing the time-evolution of near-edge x-ray spectra of a well-studied, laser-excited metalloporphyrin, Ni(II)-tetramesitylporphyrin. The use of high repetition rate, short pulse lasers as pump sources will dramatically enhance the duty cycle and efficiency in data acquisition and hence capabilities for laser-pump/x-ray probe studies of ultrafast structural dynamics at synchrotron sources.     

一次谐波锁频的快速光腔衰荡光谱检测

本文介绍了一种赫兹级响应速率的光腔衰荡光谱探测大气痕量气体的检测技术.将100 MHz正弦波调制信号加载在电光相位调制器上产生边带,用混频器提取载波与边带通过3m气体吸收池后拍频所产生的一次谐波作为误差信号,实现了1572 nm分布式反馈激光器对于二氧化碳气体分子6361.25 cm-1处超精细跃迁线的频率锁定.采用波...     

基于拉曼光谱的三组分食用调和油快速定量检测

应用激光拉曼光谱技术结合化学计量学方法实现了三组分食用调和油中菜籽油、花生油和芝麻油的快速定量检测。分别采用标准正态变量变换(SNV)+去趋势(de-trending)算法和正交信号校正(OSC)算法对600~3 000cm-1波段的原始拉曼光谱进行预处理。建立了基于非线性支持向量机(SVM)和线性偏最小二乘(PLS)回归算法的定量分析模型,并采用19个预测集通过外部交叉验证法对模型进行验证。实验结果显示:对含有菜籽油、花生油和芝麻油的三组分食用调和油,以OSC预处理后建立的线性PLS模型预测效果最好,其验证集决定系数R2p分别为0.990 4,0.965 8,0.977 1,均方根误差(RMSEP)分别为0.018 8,0.037 9,0.026 2。研究结果表明,利用激光拉曼光谱结合化学计量学方法快速定量检测三组分食用调和油中菜籽油、花生油和芝麻油的含量具有可行性,并获得了较高的预测精度。     

基于受激Raman放大器的井下人员震动定位系统的研究

通过使用激励Raman放大器提出并演示了一种125千米的长距离光FBG（光纤光栅）震动定位传感系统。在激励Raman放大器进程中,使用低功耗的1480nm激光器作为1395nm泵浦激光器的效应使得该系统可以获得125千米的测量范围。整个系统只由一个工作在1395nm的1-W的Raman泵浦激光源和一个低功率的1480nm激光器以及分别安放在50km和75kin位置上的EDF（掺铒光纤）放大器组成,并利用光纤多点定位原理实现震动点的定位,为矿井下矿难发生时人员的定位打下良好的基础。