共查询到20条相似文献,搜索用时 15 毫秒
1.
葡萄糖的特异性是实现血糖浓度检测的前提,也是论证一种血糖检测方法可行性的基础。二维相关光谱技术以其高分辨率和便捷的时序规则(Noda规则)两大优势被广泛地应用在分子间(内)反应、物质相变以及物质信息提取等研究领域。旨在应用二维相关光谱技术验证中红外光谱法无创血糖检测技术的葡萄糖特异性,首先通过分析各种离体溶液样本的二维相关光谱证明方法的理论可行性,然后开展了人体手指的中红外ATR光谱采集实验,参考OGTT方法调节实验过程中人体的血糖水平,并运用二维相关光谱技术验证所得人体光谱中的葡萄糖特征信息,从而论证中红外光谱无创血糖检测技术的可行性。 相似文献
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Q.P. Wang X.J. Zhang G.Q. Wang S.H. Chen X.H. Wu H.L. Ma 《Applied Surface Science》2008,254(16):5100-5104
Highly orientated polycrystalline ZnO films were deposited on sapphire, silicon and quartz substrates at room temperature by r.f. magnetron sputtering. Different photoluminescence (PL) spectra were observed when excited with different wavelength light. A UV emission peak (356 nm) and a blue peak (446 nm) were generated for the films on sapphire, silicon and quartz substrates, and only the 446 nm blue emission appeared for the films on glass substrates when the wavelength of the excitation light was 270 nm. With increasing the wavelength of the excitation light up to 300 and 320 nm, the UV emission disappeared for films on various substrates and the wavelength of the PL peaks increased up to 488 and 516 nm, respectively. When the wavelength of the excitation light increased to 398 nm, the PL spectrum becomes a wide band that is consistent with three emission peaks. 相似文献
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Kazunari Ozasa Shigeyuki Nemoto Mizuo Maeda Masahiko Hara 《Physica E: Low-dimensional Systems and Nanostructures》2006,32(1-2):89
We have found that the photoluminescence (PL) intensity of CdSe/ZnS nanocrystals placed on a thin film of insulator (GaAsOx/GaAs) depends on excitation wavelength through the interference effects of the excitation light. By employing the multi-reflection/interference calculation, the insulator thickness of the underlying non-uniform patterns can be evaluated by the simple observation of CdSe/ZnS PL with a couple of excitation wavelengths. Moreover, the differences observed for the temporal evolution of CdSe/ZnS PL (blue shifts and degradation) among the excitation wavelengths suggest that the photo-induced changes of chemical composition and surface ligands are responsible for blue shifts and degradation, respectively. 相似文献
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N.V. Gaponenko D.M. Unuchak G.K. Malyarevich M.V. Stepikhova A.P. Stupak M.I. Samoilovich 《Journal of luminescence》2006,121(2):217-221
Photoluminescence excitation (PLE) spectra for the emission wavelength 1.54 μm were studied for erbium-doped xerogels embedded in artificial opals and porous anodic alumina films. Opals were chosen with photonic stop-band in green spectral range, where excitation of 1.54 μm occurs most efficiently. In comparison to the structure erbium-doped titania xerogel/porous anodic alumina/silicon the photoluminescence excitation spectra for 1.54 μm emission wavelength significantly changes for the same xerogels embedded in artificial opals. Enhancement of erbium-related 1.54 μm emission was observed from the structure Fe2O3 xerogel/porous anodic alumina fabricated on silicon, having some incompletely anodized aluminium, under excitation with either the lasing source at 532 nm or xenon lamp. Evident difference in PLE spectra for erbium doped TiO2 and Fe2O3 xerogels in porous anodic alumina is observed. 相似文献
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研究了激发光增强时其对荧光关联谱(FCS)测量的影响. 强激发光产生的饱和激发会改 变激光诱导荧光的空间分布函数,从而影响FCS的测量结果. 首先根据饱和吸收的物理模型,推导出强激发光情况下有效探测区域变化的定量公式,获得了FCS测量所得到的粒子数和扩散时间与饱和激发光强和激光光强的函数关系,并用于消除饱和吸收造成的系统误差.采用Monte-Carlo模拟方法和实验,对理论分析结果进行了验证. 这将有助于完善FCS分析方法的理论模型,为高激发光强度下的FCS探测提供依据.
关键词:
荧光关联谱
饱和激发
Monte-Carlo模拟 相似文献
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In this work we develop our previous measurements of diffusion lengths in gallium nitride using the steady-state photocarrier grating (SSPG) method. We show how the use of a monomode HeCd laser as well as a photoelectrical compensation scheme improves significantly the measurement, and demonstrate the ruggedness of the SSPG technique as well as the reliability of the obtained diffusion length, which is typically in the range of several hundreds of nanometers. The small-signal photocurrent decay is exponential, with decay times in the millisecond range, a clear indication of trap-limited dynamics. We use the photocarrier grating field quenching to estimate the majority carrier drift mobility. Finally, a thermalization-limited diffusion mechanism is proposed in order to overcome a serious conflict between the experimental data and the recombination-limited SSPG diffusion theory. 相似文献
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Aernout C. D. van Enter 《Journal of statistical physics》1987,47(5-6):905-910
Some recent results on one-dimensional spin-glass models with polynomially decreasing interactions are described. 相似文献
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Aernout C. D. van Enter 《Journal of statistical physics》1985,41(1-2):315-321
We give upper bounds on the decay of correlation functions for long-rangeSO(N)-symmetric spin-glass models in one and two dimensions using McBryan-Spencer techniques. In doing so we extend recent results of Picco. 相似文献
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A miniature mid-infrared (mid-IR) methane (CH4) sensor system was developed by employing a wide-band wire-source and a semi-ellipsoid multi-pass gas cell. A dual-step differential method instead of the traditional one-step differential method was adopted by this sensor to tune measuring range/zero point and to suppress the additive/multiplicative noise. This method included a first subtraction operation between the two output signals (including a detection signal and a reference signal) from the dual-channel detector and a second subtraction operation on the amplitudes of the first-subtraction signal and the reference signal, followed by a ratio operation between the amplitude of the second-subtraction signal and the reference signal. Detailed experiments were performed to assess the performance of the sensor system. The detection range is 0–50 k ppm, and as the concentration gets larger than 12 k ppm, the relative detection error falls into the range of −3% to +3%. The Allan deviation is about 4.65 ppm with an averaging time of 1 s, and such value can be further improved to 0.45 ppm with an averaging time of 124 s. Due to the cost-effective incandescence wire-source, the small-size ellipsoid multi-pass gas cell and the miniature structure of the sensor, the developed standalone device shows potential applications of CH4 detection under coal-mine environment. 相似文献
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Pablo Baudin Dmytro Bykov Dmitry Liakh Patrick Ettenhuber Kasper Kristensen 《Molecular physics》2017,115(17-18):2135-2144
ABSTRACTThe recently developed Local Framework for calculating Excitation energies (LoFEx) is extended to the coupled cluster singles and doubles (CCSD) model. In the new scheme, a standard CCSD excitation energy calculation is carried out within a reduced excitation orbital space (XOS), which is composed of localised molecular orbitals and natural transition orbitals determined from time-dependent Hartree–Fock theory. The presented algorithm uses a series of reduced second-order approximate coupled cluster singles and doubles (CC2) calculations to optimise the XOS in a black-box manner. This ensures that the requested CCSD excitation energies have been determined to a predefined accuracy compared to a conventional CCSD calculation. We present numerical LoFEx-CCSD results for a set of medium-sized organic molecules, which illustrate the black-box nature of the approach and the computational savings obtained for transitions that are local compared to the size of the molecule. In fact, for such local transitions, the LoFEx-CCSD scheme can be applied to molecular systems where a conventional CCSD implementation is intractable. 相似文献
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Séan J. Cassady Christopher L. Strand Christopher S. Goldenstein R. Mitchell Spearrin Christopher M. Brophy Jay B. Jeffries Ronald K. Hanson 《Proceedings of the Combustion Institute》2019,37(2):1435-1443
A novel single-ended mid-infrared laser-absorption sensor for time-resolved measurements of water mole fraction and temperature was developed and deployed within the annulus of a hydrogen/air-fed rotating detonation engine (RDE). The sensor transmitted two laser beams targeting mid-infrared water transitions through a single optical port on the outer wall of the cylindrical RDE annulus and measured the backscattered radiation from the RDE inner surface using a photodetector for a round-trip path of 1.52?cm. Optimizing the sensor's optical arrangement using numerical ray tracing to minimize interference from optical emission, beam steering, and scattered laser light from window surfaces was essential to sensor performance. Scanned-wavelength-modulation spectroscopy with second-harmonic detection and first-harmonic normalization was implemented to allow for frequency-domain multiplexing of the two lasers and to suppress non-absorbing interference sources such as beam-steering and emission. Tunable diode lasers near 2551 and 2482?nm were modulated at 100 and 122?kHz, respectively, and sinusoidally scanned across the peaks of their respective water transitions at 10?kHz to provide a measurement rate of 20?kHz and detection limit of 0.5% water by mole. Experimentally derived spectroscopic parameters enabled water and temperature sensing with respective uncertainties of 7.3% and 5.3% relative to the measured values. Time-resolved and time-averaged sensor measurements of gas temperature and water vapor mole fraction allow quantitative evaluation of the combustion progress at the measurement location and thus provide a design tool for RDE optimization. Broadly, this single-ended laser sensor should find applications in other combustion systems where optical access is limited. 相似文献
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High-power, high-repetition-rate mid-infrared generation with PE-SRO based on a fan-out periodically poled MgO-doped lithium niobate 总被引:1,自引:0,他引:1
Bo Xiong Jian-Li Ma Bao-Hua Wang Ling Zhang Wei Hou Jin-Min Li 《Optics Communications》2011,284(5):1391-1394
We present a high-average-power, pulsed mid-infrared pump-enhanced singly-resonant optical parametric oscillator (PE-SRO) using a fan-out periodically poled MgO-doped lithium niobate (MgO:PPLN). The pump laser is a Q-switched Nd:YAG laser with a repetition rate of 10 kHz. When the pump power was 22.0 W, a maximum idler output power of 3.4 W at 3781.4 nm was obtained. The thermal guiding effect caused by signal absorption was observed and the crystal heating power was measured with a new method. 相似文献
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The numerical model of a Mid-infrared (MIR) P+–InAs0.48Sb0.22P0.30/n0–InAs0.89Sb0.11/N−–InAs0.48Sb0.22P0.30 double heterostructure light emitting diode (DH-LED) has been reported in this paper. The governing equation of the structure has been solved numerically under the condition of high injection using fourth order Runge-Kutta method employing the shooting algorithm. The numerical model takes into account all dominant radiative and non-radiative recombination processes, surface recombination velocity and self-absorption in the active layer of DH-LED. The DH-LED has been simulated for mid-infrared applications by considering modulation bandwidth and its dependence on active layer width, doping concentration, and injected carrier density. The effect of surface recombination velocity on the quantum efficiency, peak light intensity for different values of active layer width and doping concentration has been estimated numerically. The rise time of the structure has been evaluated by considering transient response for a step current of 50 mA. The output power of DH-LED has been computed as a function of bias current and compared/ contrasted with the reported analytical and experimental results. 相似文献
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A new excitation mechanism for interstellar Class II methanol masers—maser without population inversion is argued. The 107 GHz
masers is taken as an example to demonstrate that our new mechanism is associated with astronomical conditions. 相似文献
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应用高分辨快电子能量损失谱仪 ,绝对测量了He原子各种光学允许和光学禁戒的双电子激发过程的动量转移依赖特性 ,报道了作为动量转移函数的以内禀关联量子数K ,T和A表征的电子态 2(0 ,1 ) 2 1 Po,2 (1 ,0 ) 2 1 Se和 2(1 ,0 ) 2 1 De的Fano参数q ,fa,ρ2 ,f和S ,同时对 2(- 1 ,0 ) 2 1 Se和 2(1 ,0 ) 2 的波函数作出定性检验 .从而在实验上通过激发动力学过程研究了电子关联效应 相似文献
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Measurement and analysis of the excitation functions for alpha particle induced reactions on niobium
Stacked foil activation technique and Ge(Li) gamma ray spectroscopy have been used for determining the excitation functions
up to 45 MeV, of six reactions93Nb[(α, n), (α, 2n)
m
, (α, 2n)
g
, (α, 3n), (α,p3n) and (α, αn)]. Excitation functions were also calculated theoretically by means of the hybrid model with and without the inclusion of
pre-equilibrium emission of particles. A general agreement was found in (α, xn) type of reactions. 相似文献