AN ANALYSIS OF FOURTH DERIVATIVE SPECTRA

Abstract— –Fourth derivative spectra of chloroplast at – 196°C, obtained by four sequential differentiations of the absorption spectrum, were examined to determine the conditions for optimal signal-to-noise ratio and resolution. An appreciable improvement in the signal-to-noise ratio was found when the four differentiating intervals were nearly but not exactly equal. The process of differentiating digitized data with the computer was explored in order to define the rules for optimization of the fourth derivative curves.     

在单波长紫外可见分光光度计上测定导数吸收光谱

在单波长紫外可见分光光度计上测定样品在不同波长（λ）下的吸光度（A）,然后利用数学处理方法将λ-A转变为不同波长下的一阶、二阶及三阶导数关系,即λ-△A／△λ、λ-△^2A／△λ^2及,λ-△^3／△λ^3关系,并在计算机上利用EXCEL绘制出样品的各阶导数吸收光谱。实现了在单波长紫外可见分光光度计上测定导数吸收光谱的目的,扩大了单波长紫外可见分光光度计的应用范围。     

二价铜、镍EDTA络合物晶体的电子吸收光谱

络合物晶体的电子吸收光谱作为研究晶体的电子结构的基础内容,很早以前就得到人们注意,虽然对Cu~(2+)、Ni~(2+)等络合物电子光谱的能级的经验指认已是一项较为成熟的工作,但对吸收光谱的系统的理论计算和定量解释在以前的文献中尚不多见.近年来,我们对多种晶体的电子吸收光谱进行了定量的解释,结果表明理论计算值总是能很好地符合于实验测定值。一般说来,吸收峰位的波数误差在8%以内. 早在本世纪四十年代就奠定了乙二胺四乙酸(EDTA)在分析化学中的应用基础。     

SOME PITFALLS IN THE USE OF DERIVATIVE SPECTRA

Abstract— Several difficulties are described in the use of derivative spectra: increase in the number of apparent bands, disproportionate band heights and difficulties associated with numerical differentiation.     

蒽醌衍生物在不同酸度溶液中的吸收光谱

蒽醌类化合物是一类古老的染料,对光和热非常稳定.某些蒽醌化合物还具有稳定的非晶态和晶态结构,在一定条件下可以进行相互转换,这种材料对强光具有非线性,有潜在的应用背景^[1].为此我们设计合成了两种新的蒽醌类化合物,测试了它们在溶液中的吸收光谱,研究了溶液酸碱性对吸收光谱的影响.     

水杨醛缩对甲苯胺的吸收光谱和失活动力学研究

利用纳秒级的闪光光解方法研究了水杨醛缩对甲苯胺的瞬态吸收光谱。根据瞬态吸收光谱和动力学数据,该化合物的基本光产物被认为是一个两性离子。实验结果表明,光产物的性质与溶剂的性质和浓度有关。对该化合物的光致变色机理也进行了讨论。     

可见吸收光谱线型参数分析法测定十二烷基硫酸钠临界胶束浓度

于浓度相同的结晶紫（CV）溶液中,加入不同浓度的十二烷基硫酸钠（SDS）组成一系列含有相同浓度CV和不同浓度SDS的混合溶液。在可见光区内对每一混合溶液测定其吸收值时,可见随SDS浓度的逐步递增,在CV-单聚体吸收峰的吸收值逐渐减少;而在CV-二聚体吸收峰的吸收值逐渐增加,且随CV-二聚体浓度增加而出现的CV-二聚体与CV-单聚体的吸收光谱线相互严重重叠,光谱形状也发生渐变。运用分光光度计所配备的Origin 7．5软件中储存的高斯多峰拟合法,可自动进行重叠光谱的解析和各光谱参数（包括y0,A1,A2,ω1,ω2,xc1及xc2）的拟合计算。文中还证示,每一参数与SDS浓度之间有明显的相关性,在两者之间所作的曲线上可找到明显的转折点,与转折点相对应的、在横坐标上的SDS浓度值即为SDS的临界胶束浓度（CMC）值。文中首次报道了用吸收光谱的半峰宽对SDS浓度作图所得曲线上的转折点求得SDS的CMC值。     

PHOTOBLEACHING DIFFERENCE ABSORPTION SPECTRA OF HUMAN CONE PIGMENTS: QUANTITATIVE ANALYSIS AND COMPARISON TO OTHER METHODS

Four human cone pigment apoproteins were expressed by transfection of human tissue culture cells with the corresponding complementary DNA clones. Following reconstitution of the cone pigments by incubation with 11-cis retinal, photobleaching difference absorption spectra were obtained for the blue pigment, the green pigment, and two polymorphic variants of the red pigment. These spectra were analyzed to determine the wavelengths of maximal absorbance and the bandwidths. The recombinant cone pigment spectra were compared to human cone spectral sensitivities and cone pigment absorption spectra determined by microspectrophotometry, single-cell electrophysiology, reflection densitometry, electroretinography, and psychophysical color and brightness matching.     

DERIVATION OF PHOTOCHROME ABSORPTION SPECTRA FROM ABSORBANCE DIFFERENCE MEASUREMENTS

Abstract— A method is presented with the aid of which the absorption spectrum of at least one of the two states of a photochrome can be calculated from experimental difference spectra. It is shown that the method can be applied to (biological) photochromes contained in inhomogeneous media together with absorbing, non-photochromic impurities. This medium may have the properties of an optical waveguide.     

两种卟啉化合物在Ag溶胶表面的紫外-可见吸收光谱和表面增强拉曼散射光谱研究

表面增强拉曼散射(SERS)自1974年被Fleischmann等^[1]发现以来,日益受到人们的重视.通过SERS谱图分析,可以获得物质结构及其与基体作用的信息.由于SERS可使拉曼信号增强10⁵~10⁶倍^[2],并且在某些情况下银胶还能使表面吸附质的荧光猝灭^[3,4], SERS常用来检测一些普通拉曼光谱难以检测的样品和考察界面络合物的形成.     

STUDY ON THE NANOSECOND TRANSIENT ABSORPTION SPECTRA OF HYPOCRELLIN A

In this paper, the nanosecond transient absorption spectra and the fluorescence spectraof Hypocrellin A(HA) are examined in solvents of varying polarity. There are three absorp-tion bands in dilute HA solutions: Ⅰa, Ⅱa are defined as the triplet-triplet absorption ofHA, the band Ⅲa is supposed to be the absorption of the solvent--sepatated ion pair (SSIP).In more concentrated solutions, only the absorption of SSIP was observed. The effects ofsolvent polarity on transient absorption spectra and fluorescence spectra of HA and the effectof oxygen on the intensities of the fluorescence of HA are discussed. Then a reasonablemechanism for the photolysis of HA is proposed.     

AUTOMATIC RECORDING OF ACTION SPECTRA OF PHOTOBIOLOGICAL PROCESSES, SPECTROPHOTOMETRIC ANALYSES, FLUORESCENCE MEASUREMENTS AND RECORDING OF THE FIRST DERIVATIVE OF THE ABSORPTION CURVE IN ONE SIMPLE UNIT

Abstract— A compact, rugged and simply constructed instrument has been designed which measures action spectra of photosynthesis by delivering equal numbers of quanta between 400 and 720 nm to a sample placed upon the cathode of an oxygen sensor. The absorption spectrum is measured delivering equal numbers of quanta over the spectrum to a sample placed directly above a photoreceiver that has been adjusted in wavelength sensitivity to function as a quantum counter. All the details that are recorded by conventional high precision spectro-photometers for samples with relatively broad absorption bands (e.g. chlorophyll, carotenoids, phycobilins and living material such as algal suspensions) are resolved by the instrument. Corrected excitation spectra of fluorescence are obtained with the same instrument. Likewise the first derivative of the absorption curve may be scanned. Such recordings amplify details in the absorption spectrum, and they are particularly useful in analyses of small changes in slope. The functions described above may be operated separately or combined. The instrument has a total weight of about 10 kg, and the dimensions are ca . 60 × 40 × 30 cm. It is constructed for use in field laboratories and on board research vessels, and also for courses in biology where the principles behind photobiological analyses are illustrated. It is possible that a device of this type could be used for investigations of photosynthesis on other planets.     

ABSORPTION SPECTRA AND PPP-MO CALCULATIONS OF THIOPYRAN AND RELATED COMPOUNDS

Abstract

The absorption bands of the coumarin, the thiocoumarin and thiochromone have been examined by the PPP calculation with variable β approximation, changing with increasing ring size. The calculated longest-wavelengths (λ₁) of these series were in good agreement with the experimental values measured in ethanol. A bathochromic displacement of λ₁ produced by annelation of a benzene ring to a 2H-pyran-2-one, a coumarin and its thio analogues might be mainly due to a reduction of LUMO energy levels and/or increase of HOMO energy levels. The substituent effect on absorption spectra in the coumarin, the thiocoumarin and thiochromone series has also been examined, and discussed in terms of PPP calculations.     

ABSORPTION SPECTRA OF TCA-DENATURED RHODOPSIN AND OF A SCHIFF BASE COMPOUND OF RETINAL

Abstract— When TCA-denatured rhodopsin was frozen in liquid nitrogen, Λ_max was markedly shifted to longer wavelengths as the concentration of TCA increased. After TCA denaturation, species specific absorption disappeared and the absorption maxima of the squid pigments became identical with those of corresponding pigments of octopus.
In solutions at 5° the bathochromic shift of Λ_max of TCA denatured rhodopsin was observed at higher concentrations of TCA than in the frozen state. Λ_max of N-retinylidene-butylamine (NRB) was also displaced towards longer wavelengths with increasing concentrations of TCA. This bathochromic shift was enhanced by freezing. The mode of the bathochromic shift of Λ_max provoked by TCA was very similar both in the cases of denatured rhodopsin and of NRB. The absorption spectrum of NRB was identical in shape with that of TCA-denatured rhodopsin, as the half-band widths of both materials were about 5500 cm^-1 in the liquid state and 5000 cm^-1 in the frozen state. Λ_max of retinal and NRB were red shifted in polar and polarizable solvents.
It was concluded that the strong acidity and the relatively large polarizability of TCA are responsible for the bathochromic shift of Λ_max of the Schiff base in TCA-denatured rhodopsin.     

THE EFFECT OF pH ON THE ABSORPTION AND FLUORESCENCE SPECTRA OF SANGUINARINE

Abstract— The influence of pH in the range 1.0 to 13.0 on the structure of sanguinarine has been investigated by spectrophotometric and spectrofluorimetric measurements. The data on absorption maxima, molar extinction coefficient, fluorescence emission maxima, relative fluorescence intensity and fluorescence quantum yield of the sanguinarine under various pH are presented. It is suggested that the pH dependent absorbance and fluorescence property of sanguinarine is due to the formation of the carbinolamine by hydroxylation at C-6 at alkaline pH.