721型分光光度计分光系统常见故障的排除

721型分光光度计分光系统的常见故障有无出射单色光或光斑不完整、单色光波长指示值与实测值不一致、波长调节器转动时出射光波长无变化、波长调节器转动困难且波长读数盘不动等，分析了造成这类故障的原因，并阐述了排除这类故障的方法。     

Wavelength accuracy and reproducibility of a high resolution computer-controlled monochromator

When using a monochromator, the knowledge of the instrumental wavelength of the spectral lines is essential. In this work it was first examined how accurate these wavelengths can actually be predicted using a function which was fitted through experimental data. These data were obtained from instrumental wavelength measurements over the entire operational wavelength range. Secondly, the possible uncertainty on the instrumental wavelength was investigated and was found to be dependent on temperature changes and mechanical imprecisions. A study of the temperature effect on the instrumental wavelength was undertaken and efforts were made to trace the cause of this temperature dependence. The applicability of the prediction of wavelength shifts due to temperature changes using experimental data was tested. Having taken the necessary thermostating precautions, the remaining wavelength uncertainty for multi- and single-line analyses was isolated. In the light of experimental findings, the optical calibration procedure w.as evaluated. Finally, the need for a sound equilibrium between resolution and wavelength reproducibility was emphasized.     

HPLC紫外分光检测器的波长范围、波长准确度和波长重复性及其测试方法的探讨

根据实践,提出了高压液相色谱（HPLC）紫外分光检测器的波长范围、波长准确度和波长重复性等技术指标的具体、简易、可行的测试方法,可供有关设计、制造、使用者参考．     

TEMPORAL SHIFTS IN BIOLUMINESCENCE EMISSION SPECTRA FROM THE DEEP-SEA FISH, Searsia koefoedi

Abstract— The luminescence of freshly collected exudate from the post-cleithral organ of the deep-sea searsiid fish. Searsia koefoedi , was increased in intensity by the addition of hydrogen peroxide and exhibited emission maxima at 408 nm and 478 nm. Initially, the spectrum was unimodal with a long wavelength peak and a short wavelength shoulder. With time, the short wavelength peak increased in relative magnitude; the spectrum became bimodal, then the short wavelength peak predominated. The measured time-dependent changes in the spectral distribution resulted from differences in the rates of decay of the two peaks. The short wavelength peak exhibited first order exponential decay with a mean (± standard deviation) decay constant of -0.13 ± 0.02 min^-1 ( N = 4). Decay of the long wavelength peak proceeded approximately twice as fast and was best defined by a double exponential function.     

Material design of retardation films with extraordinary wavelength dispersion of orientation birefringence: a review

Orientation birefringence and its wavelength dispersion for various types of cellulose esters are reviewed. Cellulose esters such as cellulose acetate propionate and cellulose acetate butyrate show positive orientation birefringence with extraordinary wavelength dispersion, which is determined mainly by the ester groups rather than the main chains. The acetyl group provides negative orientation birefringence with strong ordinary wavelength dispersion, whereas the propionyl and butyryl groups give positive orientation birefringence with weak wavelength dispersion. Although all groups show ordinary wavelength dispersion, the summation of their orientation birefringences gives extraordinary dispersion. Moreover, the wavelength dispersion is dependent on the stretching ratio due to the difference in the orientation relaxation of each group. On the contrary, cellulose triacetate (CTA) shows negative birefringence with ordinary wavelength dispersion because it has no positive contribution. However, doping a plasticizer having positive orientation birefringence changes the orientation birefringence of CTA from negative to positive, and the wavelength dispersion from ordinary to extraordinary. This is attributed to the cooperative orientation of plasticizer molecules to the stretching direction with CTA chains, known as nematic interaction upon a hot drawing process.     

EXCITATION WAVELENGTH DEPENDENCE OF PROTOTROPIC DISSOCIATION AND TAUTOMERISM OF SALICYLAMIDE IN THE LOWEST EXCITED SINGLET STATE

Abstract—The fluorescence spectra of salicylamide in cyclohexane, ethanol and at different pH in water were studied. The short and long wavelength fluorescences observed in the organic solvents originate from emissions of a weakly or non-intramolecularly hydrogen bonded conformer and from phototautomerization of a strongly intramolecularly hydrogen bonded conformer, respectively. Evidence for at least 2 conformers in the ground state exists in the excitation wavelength dependence of the ratio of short wavelength to long wavelength emission. In water, prototropic dissociation of the phenolic group of salicylamide in the lowest excited singlet state also shows an excitation wavelength dependence, indicating that the weakly or non-intramolecularly hydrogen bonded conformer in water is predominately responsible for photodissociation.     

Net analyte signal-based simultaneous determination of antazoline and naphazoline using wavelength region selection by experimental design-neural networks

Net analyte signal (NAS)-based multivariate calibration methods were employed for simultaneous determination of anthazoline and naphazoline. The NAS vectors calculated from the absorbance data of the drugs mixture were used as input for classical least squares (CLS), principal component and partial least squares regression PCR and PLS methods. A wavelength selection strategy was used to find the best wavelength region for each drug separately. As a new procedure, we proposed an experimental design-neural network strategy for wavelength region optimization. By use of a full factorial design method, some different wavelength regions were selected by taking into account different spectral parameters including the starting wavelength, the ending wavelength and the wavelength interval. The performance of all the multivariate calibration methods, in all selected wavelength regions for both drugs, was evaluated by calculating a fitness function based on the root mean square error of calibration and validation. A three-layered feed-forward artificial neural network (ANN) model with back-propagation learning algorithm was employed to model the nonlinear relationship between the spectral parameters and fitness of each regression method. From the resulted ANN models, the spectral regions in which lowest fitness could be obtained were chosen. Comparison of the results revealed that the net NAS-PLS resulted in lower prediction error than the other models. The proposed NAS-based calibration method was successfully applied to the simultaneous analyses of anthazoline and naphazoline in a commercial eye drop sample.     

QUANTUM YIELDS FOR LASER PHOTOCYCLIZATION OF BILIRUBIN IN THE PRESENCE OF HUMAN SERUM ALBUMIN. DEPENDENCE OF QUANTUM YIELD ON EXCITATION WAVELENGTH

The quantum yield for laser photocyclization of bilirubin to lumirubin in the presence of human serum albumin (phi LR) was measured at five monochromatic excitation wavelengths in the range 450-530 nm. Solutions used were optically thin throughout the wavelength range and precautions were taken to exclude contributions from photocyclization of bilirubin XIII alpha impurities. The values obtained (7.2-18 x 10(-4] were lower than those previously reported and showed the following wavelength dependence: 457.9 less than 488.0 less than 501.7 less than 514.5 approximately equal to 528.7. However, the rate of lumirubin formation, normalized to constant fluence, decreased with wavelength over the same wavelength range and no evidence was found that photoisomerization of bilirubin to lumirubin is faster with green (514.5 or 528.7 nm) than with blue (457.9 or 488.0 nm) light. The stereoselectivity of the configurational isomerization of bilirubin to 4Z,15E and 4E,15Z isomers also was studied. This reaction became less regioselective for the 4Z,15E isomer with increasing wavelength. The observed wavelength dependence of phi LR and of the [4E,15Z]: [4Z,15E] ratio at photoequilibrium are consistent with an exciton coupling model in which intramolecular energy transfer can occur between the two pyrromethenone chromophores of the bilirubin molecule in the excited state. Relative rates of lumirubin formation in vivo at different excitation wavelengths and constant fluence were estimated for different optical thicknesses and for different skin thicknesses. These estimates suggest that the recently reported clinical equivalence of blue and green phototherapy lights probably reflects the marked variation of skin transmittance with wavelength more than wavelength-dependent photochemistry. The calculations also indicated that the optimal wavelength for phototherapy is probably on the long wavelength side of the bilirubin absorption maximum.     

KINETIC STUDIES OF THE TWO LIGHT REACTIONS IN PHOTOSYNTHESIS

Abstract— The decay kinetics of the photo-induced absorbance changes in red and green algae are very sensitive to the wavelength of the actinic light. A four to tenfold increase in half-decay time is noted in going from short wavelength (550–650 mμ) to long wavelength (> 700 mμ) excitation. The slow decay rates produced by long wavelength light can be enhanced with a steady background of short wavelength light. A relationship between initial decay rates and O₂ evolution rates is described. This relationship allows a direct correspondence between these spectroscopic studies and the 'red-drop' and 'enhancement' experiments of Emerson.     

A Rapid-Scanning Spectrometer with Wavelength Synchronization by a Laser Rotary Encoder for Versatile Applications to Atomic Emission Spectrometry

A rapid-scanning spectrometer was developed for versatile use in atomic emission spectroscopy. The sine bar was removed and a laser rotary encoder was fitted to the grating shaft for wavelength synchronization. The pulses produced by the encoder when the grating shaft was driven back and forth in sector movements were counted to detect the grating angle and the wavelength. The wavelength accuracy and precision obtained were ±0.26 and ±0.013 nm, respectively. The maximum scanning speed was limited below 4000 nm/s by a malfunction in wavelength synchronization. The rapid-scanning spectrometer was successfully used for multielement determinations, correction of background emission, and characterization of an inductively coupled plasma.     

聚对苯二甲酸乙二酯荧光光谱的激发波长依赖性研究

聚对苯二甲酸乙二酯（PET）的荧光光谱已经得到了相当广泛和深入的研究,当激发光波长位于310～360nm时,可以观察到位于360～390nm范围的荧光发光,这部分荧光的来源有很多争议,至今未取得一致的看法,有作者认为,此处的荧光发光是PET链段上苯环之间的相互作用形成的基态二聚体（ground-state dimer）引起的发光;还有人认为这是苯环基团之间相互作用形成的激基缔合物的发光（excimeric emission）。     

WAVELENGTH DEPENDENCE FOR AMT CROSSLINKING OF pBR322 DNA

Abstract The wavelength dependence for 4'aminomethyl-4,5',8-trimethylpsoralen crosslinking of a linearized plasmid DNA (pBR322) by narrow band UV-A light (298–382 nm) has been determined. Maximal levels of crosslinking occurred with light in the 322–346 nm range. Crosslinks were shown to be photoreversible by shorter wavelength photons (298 and 310 nm). The correlation between the wavelength dependence for crosslink formation and the optimal wavelength for most psoralen action spectra further supports the notion that crosslinks are the major lesion responsible for the effectiveness of psoralen plus ultraviolet A therapies.     

Absorption cross-sections of NO2 in the UV and visible region (200 – 700 nm) at 298 K

The absorption cross-sections of NO₂ have been measured in the wavelength range 200 – 700 nm at 298 K with a spectral resolution of 0.04 nm. The data were acquired digitally, allowing post-processing such as integration in different wavelength intervals. The cross-sections are averaged over 1 nm intervals and over the atmospheric wavelength intervals used in solar photolysis calculations.     

表面等离子体激元共振光化学传感器的研究

自行设计并组装了一套全波长表面等离子体激元共振光化学传感器实验装置;研究了以银膜为基底的传感器的稳定性、可逆性及干扰情况;在575nm波长处,测定乙醇的灵敏度为4.6×10^-4折射率单位,RSD≤1.4%,定量测定范围为0.5%～70%.分析了一些实际样品,结果与标准方法的测定值相吻合.     

基于颜色主波长与补色波长的比色法定量检测

利用sRGB(Standard RGB)颜色空间与国际照明委员会(CIE)色度系统的转化关系以及CIE 1931色品图的性质,编写MATLAB程序实现了颜色的RGB信息到颜色主波长或补色波长的转化,并将此程序用于分析面光源下采集到的显色产物的图片。利用颜色的主波长实现了对pH值的定量检测,利用颜色的补色波长完成了对亚硝酸根离子的定量检测。当pH值分别在4.0~7.0和7.5~10.0范围内,pH值均与其显色产物颜色的主波长呈线性变化;亚硝酸根离子浓度在10~40 mg/L范围内与其显色产物颜色的补色波长有良好的线性关系,通过结合图片的G值分析,扩大了传统吸收光谱法的检测范围。     

聚苯乙炔立体结构与光致发光性能关系的研究

使用有机金属铑、金属钨 /四苯基锡催化剂体系聚合苯乙炔 ,分别获得了高产率和高分子量的聚苯乙炔 .使用UV ,IR ,NMR ,GPC等分别对聚合物结构进行了表征 .采用不同波长的激发光对聚合物荧光性能进行研究 ,详细分析了聚合物结构与荧光性能之间的关系 .研究结果发现 ,不同聚合物结构对聚合物荧光性能产生很大影响 ,规整性高的聚合物 ,将有较高的发光量子效率 ;聚合物规整性差 ,将可能导致多个荧光发光结构点 ,其荧光强度降低 .聚合物荧光光谱研究将对某些共轭聚合物结构的规整性分析提供一些有用的信息     

液相色谱仪波长校准的新方法

提出了用咖啡因乙腈溶液进行高效液相色谱仪(HPLC)波长校准的新方法,并在两台高效液相色谱仪上进行了实验,实验结果均能达到JJG705-2002液相色谱仪检定规程中关于波长示值误差与波长准确度检定的要求。相对于原波长检定方法,该方法简单易行,对仪器没有任何污染。     

Effect of the Wavelength of the Laser Beam on the Response of an Evaporative Light Scattering Detector

Abstract

The effects of the wavelength of the laser beam on the response of an evaporative light scattering detector (ELSD) are discussed. Data characterizing the response of the detector and its dependence on the sample size have been collected for six solutes, using a pulsed dye laser as light source. The experimental results suggest that there is little influence of the wavelength on the intensity of the scattered light. On the other hand, the noise decreases in proportion to the wavelength of the incident light beam. Thus, the detection limit (at constant value of the signal to noise ratio) decreases with decreasing wavelengths. The performance of the ELSD improves when a short wavelength is used.     

Power-law analysis of surface-plasmon-enhanced electromagnetic field dependence of blinking SERS of thiacyanine or thiacarbocyanine adsorbed on single silver nanoaggregates

Blinking statistics in surface-enhanced Raman scattering (SERS) of thiacyanine or thiacarbocyanine adsorbed on single Ag nanoaggregates were analyzed by a power law. A power law reproduces the probability distributions of both the bright and dark SERS occurrences against their duration times. As the localized surface plasmon resonance (LSPR) wavelength of a single Ag nanoaggregate approached the excitation wavelength or the excitation laser intensity increases, the power-law exponents were close to -1.5, a value derived from a one-dimensional random walk model. When the LSPR wavelength left the excitation wavelength or the excitation laser intensity decreases, the power-law exponents deviated from -1.5. The decrease in the power-law exponents in the bright SERS, which indicates a decrease in the probabilities of the long-lived bright SERS, and the increase in the power-law exponents in the dark SERS coincide with the increasing shallowness and narrowing of a optical trapping potential well due to a surface-plasmon-enhanced electromagnetic field around a junction of the Ag nanoaggregates excited at a wavelength apart from the LSPR wavelength or under the low laser intensity, i.e., the low original electromagnetic field, respectively.     

A quantum yield map for synthetic eumelanin

The quantum yield of synthetic eumelanin is known to be extremely low and it has recently been reported to be dependent on excitation wavelength. In this paper, we present quantum yield as a function of excitation wavelength between 250 and 500 nm, showing it to be a factor of 4 higher at 250 nm than at 500 nm. In addition, we present a definitive map of the steady-state fluorescence as a function of excitation and emission wavelengths, and significantly, a three-dimensional map of the "specific quantum yield": the fraction of photons absorbed at each wavelength that are subsequently radiated at each emission wavelength. This map contains clear features, which we attribute to certain structural models, and shows that radiative emission and specific quantum yield are negligible at emission wavelengths outside the range of 585 and 385 nm (2.2 and 3.2 eV), regardless of excitation wavelength. This information is important in the context of understanding melanin biofunctionality, and the quantum molecular biophysics therein.