Surface enhanced infrared spectral investigation of 2,3-bis(chloromethyl)anthracene-1,4,9,10-tetraone on silver nanoparticles

The size effect of silver nanoparticles on photophysical properties of 2,3-bis(chloromethyl)anthracene-1,4,9,10-tetraone (BCMAT) has been investigated using an IR technique. Silver colloids of different sizes have been prepared by two different methods. Mechanisms for adsorption and complex formation have been elucidated from surface-enhanced infrared absorption spectra. The observation shows that BCMAT is adsorbed on silver nanoparticles through a C = O group and that its orientation is stand-on. Surface enhancement factors have been calculated. As the particles decrease in size their total surface area grows, which leads to the gain in the enhancement factor.     

Infrared Study of The Hydrogen Bond Complexes Involving 2,3-bis-(2-Pyridyl)-pyzazine and Proton Donors. Comparison with Monofunctional Heterocyclic N-Bases

The hydrogen bond complexes between phenols and 2,3-bis(2-pyridyl)-pyrazine BPP) are investigated by infrared spectroscopy in carbon tetrachloride solution. The formation constants for the complexes of 1–1 stoichiometry are higher than those predicted from the pK_a of BPP. This is also the case for other N-heteroaromatic bases (pyridazine, 2,2′-bipyrimidine) characterized by two vicinal equivalent nitrogen atoms. The thermodynamic and infrared data of the complexes show that BPP cannot be considered as a proton sponge.     

An Infrared Spectroscopic Study of Crystalline Copper (II) Propionate and Butyrate

Abstract

Abstract: The vibrational spectra of crystalline anhydrous copper (II) propionate and butyrate were studied by FT-IR spectroscopy. A detailed assignment of the spectra of both compounds is presented and discussed. It is shown that the presence of two non-equivalent sets of carboxylate ligands within the crystals gives rise to several band splittings, which are particularly evident in those bands ascribable to normal modes involving predominantly the -C_βH₃ or -C_βH₂-fragments. In addition, the vibrational assignments made for the studied molecules are shown to be very useful to help understanding the much more complex spectra of long chain copper carboxylates.     

Solvatochromism,Preferential Solvation of 2,3-Bis(Chloromethyl)-1,4-Anthraquinone in Binary Mixtures and the Molecular Recognition Towards <Emphasis Type="Italic">p</Emphasis>-Tert-Butyl-Calix[4]arene

Optical absorption and fluorescence emission spectra of 2,3-bis(chloromethyl)-1,4-anthraquinone (DCMAQ) in single solvents namely, carbon tetrachloride, acetonitrile, chloroform, propan-2-ol and its binary mixtures [carbon tetrachloride/chloroform, chloroform/acetonitrile, chloroform/propan-2-ol] have been investigated. The preferential solvation of DCMAQ in above mixtures has been studied by monitoring the absorption and fluorescence spectra of DCMAQ. The spectral features indicate that DCMAQ is preferentially solvated by CHCl₃ in the above mixtures. This can be elucidated from the local mole fraction, non-linearity in transition energy plot, preferential solvation index (δ _s2) and (f ₂/f ₁) values. Molecular recognition properties of p-tert-butylcalix[4]arene (tBC) to DCMAQ via hydrogen bonding and π–π interaction were sensed successfully on the basis of absorption and fluorescence emission spectroscopies, by which the stoichiometry ratio and the binding constant of the tBC–DCMAQ complex were determined.     

基于近红外光谱的玉米籽粒CNCPS组分分析及预测研究

试验旨在研究应用近红外光谱技术快速测定玉米籽粒粉末CNCPS组分的可行性。65个样品来自黑龙江省,选用偏最小二乘法(PLS)为建模方法,采用二阶导数和Norris导数滤波法处理光谱数据后,建立了玉米籽粒粉末中干物质(DM)、粗蛋白质(CP)、粗脂肪(Fat)、粗灰分(Ash)、淀粉(Starch)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)、可溶性蛋白(SP)、酸性洗涤不溶蛋白(ADIP)和中性洗涤不溶蛋白(NDIP)等的近红外预测模型。其中DM,CP,Fat,Ash,Starch,NDF和ADF的决定系数分别为0.974 3,0.968 3,0.947 8,0.909 8,0.977 7,0.935 4和0.926 9,标准差(SD)与预测均方根(RMSEP)的比值(SD/RMSEP)值分别为3.96,4.78,3.75,4.25,4.13,3.88和3.12。SP的决定系数为0.857 5,SD/RMSEP值为3.06。ADIP和NDIP的决定系数分别为0.531 9和0.683 3,SD/RMSEP值分别为5.50和2.85。试验结果表明,近红外技术可以用于玉米籽粒粉末CNCPS组分的快速测定,但降低ADIP和NDIP测定误差有待进一步研究。     

用傅立叶变换红外光谱法研究核辐照对虫草粉成分的影响

本文采用傅立叶变换红外光谱(卷积谱及二阶导数谱)法对经不同剂量核辐照的虫草粉进行了对比研究。虫草粉中碳水化合物(糖和纤维素)、蛋白质及脂肪含量较高; 虫草的多糖及酯对核辐照较为敏感, 辐照还使分子中吡喃环的C-O-H基团向多糖的O-H和酯的C-O-C基团转化; 构成虫草蛋白质的多肽是α构象的; 低于18 kGy剂量辐照虫草粉样品对虫草蛋白质影响很小, 但对虫草主要有效成分(含有C-N基团和N-H基团成分)影响较大; 高于18 kGy剂量辐照虫草粉样品对虫草蛋白质、多糖及酯的分子结构可能产生了破坏。建议不宜采用核辐照对虫草粉杀菌消毒处理。     

Infrared vibrational spectra of -histidinium dihydrogen orthophosphate orthophosphoric acid (LHP)

The entire vibrational spectrum of a single crystal of -histidinium dihydrogen orthophosphate orthophosphoric acid (LHP) was studied by infrared (IR) spectroscopy from 10 up to 4000 cm⁻¹. The polarized infrared (IR) reflectivity spectra were measured between 7 and 250 K, in the frequency range 10–600 cm⁻¹. From the IR spectral analysis, the phonon modes were classified within their symmetry species, and their longitudinal (LO) and transversal (TO) optical frequencies were calculated. A tentative assignment of the various internal modes observed in the transmissivity spectrum of LHP, between 300 and 4000 cm⁻¹, is proposed. The present study did not reveal any low-temperature structural phase transition.     

4,4''-二甲氨基二苯乙烯双光子吸收理论研究--溶剂效应

对最近实验室合成的分子材料 4 ,4 ' 二甲氨基二苯乙烯的双光子吸收特性在从头计算的基础上进行了理论研究。理论模型是建立在密度泛函理论的基础上的。利用含时的密度泛函理论来计算分子的非线性光学性质 ,而溶剂效应则通过自洽响应场方法的极化连续模型来模拟。计算结果表明 ,三态模型可以很好地给出该分子在低激发态范围内的双光子吸收截面。随着溶剂极性的增加 ,单光子波长红移 ,双光子吸收截面增加。双光子吸收截面的大小和实验给出的结果符合得较好。     

近红外光谱技术(NIRS)在干草品质检测中的研究与应用

干草品质对动物的生产性能、牧草价值和最终盈利有着最直接的影响,检测干草品质的方法也在不断改进,近红外光谱技术(NIRS)这种快速、 高效而无破坏性的现代检测技术已在饲草料中广泛应用。文章阐述了应用NIRS分析干草品质的可行性和高效性,详细介绍了NIRS用于检测牧草营养成分、真菌侵染程度、内生真菌产生的有毒物质以及一些难于用化学方法检测的微量成分等重要指标的研究成果。指出NIRS用于分析干草品质突破了过去常规化学方法的复杂、耗时、成本高等缺陷,是干草品质分析方法的一个重大进步,并期待着NIRS在牧草品质中的应用研究工作继续完善和发展,建立更精确的定标模型以及更系统的分析软件,促进畜牧业的快速发展。     

Adsorption and thermal chemistry of acrolein and crotonaldehyde on Pt(111) surfaces

The surface chemistry of acrolein and of crotonaldehyde on Pt(111) single-crystal surfaces was investigated under vacuum by temperature-programmed desorption (TPD) and reflection-absorption infrared (RAIRS) spectroscopies. The main thermal decomposition path seen for both compounds was the expected decarbonylation of the unsaturated aldehyde to carbon monoxide and the corresponding olefin (ethene and propene, respectively), but small amounts of propene and ketene were detected in the case of acrolein as well. The RAIRS data indicate that while acrolein initially adsorbs with its plane parallel to the surface and interacts mainly via the carbonyl group, crotonaldehyde adopts a more complex geometry where the main interaction to the metal is via a rehybridization of the C=C double bond. It is suggested here that the changes in adsorption geometry induced by substitutions in the C=C double bond may be responsible for the observed changes in the subsequent reactivity of the adsorbed unsaturated aldehydes.     

Spectra,Magnetic Property and Coordination Structure Study on Polymeric Copper(II) Iodo Complex of Diethylenetriamne

Abstract

Polymeric [Cu(dien)Ix] (dien = diethylenetriamine) was prepared. Its electronic absorption spectrum and photoacoustic spectrum were recorded at room temperature. They were compared with each other and the results were discussed quantitatively with respect to ligand field theory (LFT) and the radical scaling wave function of a non-free copper(II) ion. The theoretical values are in agreement with the observed ones. In addition. the ESR spectra of the title complex were measured at 77k and room temperature, respectively. They were compared with each other and characterized. Therefore, the electronic structure was also investigated with its spectra behaviors and PLFT. The spectra and the theoretical analysis about the title complex suggest there is a weak interaction between the Cu-Cu. It can be interpreted with using Kahn's theory. The g (= 2.0942) is greater than 2.040, conforming to a ground state configuration with unpaired electron in the dx²?y² orbital.     

用傅立叶变换红外光谱法研究核辐照对人参粉成分的影响

本文采用傅立叶变换红外光谱(吸收光谱、二阶导数谱及差谱)法对经不同剂量核辐照的人参粉进行了对比研究.辐照剂量不高于9 kGy时,人参粉样品的化学成分几乎没有发生变化;人参粉样品经15kGy及以上的辐照剂量辐照后,可能产生新的化学成分,表明采用辐照剂量不高于9 kGy的核辐照杀灭人参粉污染的微生物和各种寄生虫卵是可行的;...     

Fourier Transform Infrared Spectroscopic Investigation on Langmuir-Blodgett Films of Octadecanoyl Ester of 1-(2-Carboxyethyl) Thymine: Molecular Orientation,Molecular Recognition to Complementary Base of Nucleic Acid and Order-Disorder Transition

Fourier transform infrared (FTIR) transmission, polarized transmission, reflection absorption (RA) and Attenuated total reflection (ATR) spectroscopy were employed to investigate the molecular orientation and molecular recognition to the complementary base at the air / water interface of a novel nucleolipid amphiphile, octadecanoyl ester of 1-(2-carboxyethyl) thymine. It has been found that the molecules are biaxially oriented and the hydrocarbon chain titled considerably from the substrate normal as well as the chromophoric part in the LB film Molecular recognition through complementary bases pairing takes place at the air / water interface between the thymine moiety in the head group of the amphiphile and adenosine in the subphase, the hydrogen involved in the host-guest interactions has been detected by using FTIR-ATR technique. FTIR transmission spectra measured at elevated temperatures revealed that the order-disorder transition of the LB film which contains the complementary base occurs at lower temperature. To our best knowledge, investigation of the order-disorder transitions in nucleolipid amphiphile LB films and comparative studies of the order-disorder transitions between nucleolipid amphiphile LB film that contains and does not contain the complementary bases have been virtually nonexistent, so far.     

KCl对含有纳米银的[Ru(bpy)3]2+荧光性能影响

通过吸收光谱、荧光光谱等手段研究了KCl对含有纳米银的金属钌联吡啶配合物([Ru(bpy)3]2 )的荧光性能的影响.结果表明,KCl与纳米银粒子间存在较强的相互作用,这种强的相互作用破坏了[Ru(bpy)3]2 与纳米银粒子间的链状网络结构,形成大颗粒和团聚体.同时,在吸收光谱的长波段处观察到明显的新的吸收带,随着KCl量的增加,新吸收带峰值逐渐红移并展宽.随着KCl量的增加,[Ru(bpy)3]2 荧光强度先猝灭而后逐渐增强,直至达到一个定值.文章从分子间的相互作用、能量传递等方面探讨了KCl对含有纳米银的[Ru(bpy)3]2 荧光性能影响机理.     

Effect of the Protonation and Chemical Doping of Poly(o-toludine) with Copper Sulfate on the Spectral and Electrical Properties of the Host Polymer

Poly(o-toluidine) (POT) and its samples doped with copper sulfate, a transition metal salt, were synthesized by a chemical oxidative polymerization technique using potassium dichromate as oxidant in aqueous hydrochloric acid medium and chemical doping with copper sulfate. The prepared polymeric samples were characterized by ultraviolet (UV)-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction, and DC conductivity measurement techniques. The UV-visible spectra of doped polymer displayed peaks indicating the presence of charged particles/polarons and/or formation of conducting POT. The characteristic FTIR peaks of the doped polymer provided information regarding structural changes in the backbone of POT and were consistent with the interaction of the benzenoid groups of the polymer with metal ions. X-ray diffraction patterns of powdered doped polymer showed an amorphous nature, as exhibited by most conducting polymers. The DC conductivity of doped polymer was measured by a two-probe method in the temperature range of 300–400 K; a significant enhancement in DC conductivity was observed with an increase in temperature, showing the semiconductor nature of the synthesized doped polymer.     

Infrared reflection absorption study of carbon monoxide adsorption on Cu(1 0 0)-c(2 × 2)-Pd surfaces formed by palladium vacuum-depositions at various temperatures

Using infrared reflection absorption spectroscopy (IRRAS) and temperature programmed desorption (TPD), we investigated carbon monoxide (CO) adsorption and desorption behaviors on atomic checkerboard structures of Cu and Pd formed by Pd vacuum deposition at various temperatures of Cu(1 0 0). The 0.15-nm-thick Pd deposition onto a clean Cu(1 0 0) surface at room temperature (RT) showed a clear c(2 × 2) low-energy electron diffraction (LEED) pattern, i.e. Cu(1 0 0)-c(2 × 2)-Pd. The RT-CO exposure to the c(2 × 2) surfaces resulted in IRRAS absorption caused by CO adsorbed on the on-top sites of Pd. The LEED patterns of the Pd-deposited Cu(1 0 0) at higher substrate temperatures revealed less-contrasted c(2 × 2) patterns. The IRRAS intensities of the linearly bonded CO bands on 373-K-, 473-K-, and 673-K-deposited c(2 × 2) surfaces are, respectively, 25%, 22%, and 10% less intense than those on the RT-deposited surface, indicating that Pd coverages at the outermost c(2 × 2) surfaces decrease with increasing deposition temperature. In the initial stage of the 90-K-CO exposure to the RT surface, the band attributable to CO bonded to the Pd emerged at 2067 cm⁻¹ and shifted to higher frequencies with increasing CO exposure. At saturation coverage, the band was located at 2093 cm⁻¹. In contrast, two distinct bands around 2090 cm⁻¹ were apparent on the spectrum of the 473-K-deposited surface: the CO saturation spectrum was dominated by an apparent single absorption at 2090 cm⁻¹ for the 673-K-deposited surface. The TPD spectra of the surfaces showed peaks at around 200 and 300 K, which were ascribable respectively to Cu-CO and Pd-CO. Taking into account the TPD and IRRAS results, we discuss the adsorption-desorption behaviors of CO on the ordered checkerboard structures.     

Magnetic Field-Effect on Photoluminescence of Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) Nanoparticles in a Poly[vinyl butyral] Matrix

Abstract

In this work the magnetic field effects (MFE) on the photoluminescence of MEH-PPV film and nanoparticles were obtained using the MFE technique with continuous-wave photoexcitation. The analysis of the MFE dependence for the MEH-PPV film gave a HWHM (half-width at half maximum) ～ 65?mT and a total MFE value about 102.8% at 200?mT whereas the MFE dependence of the MEH-PPV nanoparticles showed significant broadening, with their HWHM ～ 280?mT and a total MFE value of 99% at 550?mT. By a simple theoretical model based on rate equations, the mechanism of the negative magnetic field effect was explained. The observed negative effect was the result of the dominant singlet exciton formation rate in the MEH-PPV nanoparticles. For explaining this negative effect the enhanced triplet-triplet annihilation due to confinement of triplet excitons in the nanoparticles and singlet molecular oxygen-triplet exciton annihilation were proposed.     

Ex-situ prepared films of 4-aminothiophenol on Au(1 1 1): photoemission, NEXAFS and STM measurements

Ex-situ prepared films of 4-aminothiophenol (4-ATP) on Au(1 1 1) have been studied by core-level photoemission using synchrotron radiation, ultra-high-vacuum scanning tunneling microscopy and spectroscopy (UHV-STM, STS), and X-ray absorption (NEXAFS). Photoemission measurements suggest that the film contains a relatively low percentage of 4-ATP bonded to the Au surface, with the presence of free 4-ATP, with oxidised and possibly dimerised molecules also present. We find a lower oxide content than has previously been observed, with well-resolved STM images. These images show a disruption of the long range order of the Au(1 1 1)-(22 × √3) reconstruction, with local nucleation of the reconstruction apparently induced by the 4-ATP, and bias-dependent contrast images. This latter effect, together with the asymmetry observed in STS, is ascribed to the presence of oriented molecular dipole layers between the metal and the organic material. NEXAFS data suggest a broadly upright geometry, with, however, considerable uncertainties.     

Geometrical characterization of adenine and guanine on Cu(1 1 0) by NEXAFS, XPS, and DFT calculation

Adsorption of purine DNA bases (guanine and adenine) on Cu(1 1 0) was studied by X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine-structure spectroscopy (NEXAFS), and density-functional theory (DFT) calculation. At coverages near 0.2 monolayers, Angular-resolved NEXAFS analysis revealed that adenine adsorbates lie almost flat and that guanine adsorbates are tilted up on the surface with the purine ring parallel to the atom rows of Cu(1 1 0). Referring to the previous studies on pyrimidine DNA bases [M. Furukawa, H. Fujisawa, S. Katano, H. Ogasawara, Y. Kim, T. Komeda, A. Nilsson, M. Kawai, Surf. Sci. 532-535 (2003) 261], the isomerization of DNA bases on Cu(1 1 0) was found to play an important role in the adsorption geometry. Guanine, thymine and cytosine adsorption have an amine-type nitrogen next to a carbonyl group, which is dehydrogenated into imine nitrogen on Cu(1 1 0). These bases are bonded by the inherent portion of -NH-CO- altered by conversion into enolic form and dehydrogenation. Adenine contains no CO group and is bonded to Cu(1 1 0) by participation of the inherent amine parts, resulting in nearly flatly-lying position.     

Time-Resolved Reflectance of an Optical Pulse in Adult Heads Based on the Finite Difference Time Domain (FDTD) Analysis

Time-resolved reflectance of an optical pulse in adult head models including non-scattering cerebrospinal fluid (CSF) has been analyzed by the finite difference time domain (FDTD) analysis formulated by the authors. Averaged light intensity and mean time of flight dependences on the source-detector separations calculated by the FDTD analysis are in good agreement with previous experiments, hybrid finite element method (FEM) and Monte Carlo calculations, which justify the FDTD analysis. Based on the analysis, time-resolved reflectance sensitivities to detect optical property changes in brain have been analyzed. As a result, it has been become clear that the sensitivities to detect absorption changes of brain are enhanced in time-resolved reflectance compared to the sensitivities in averaged light intensity, whereas the sensitivities to detect scattering property changes of brain are almost the same in time-resolved reflectance and in averaged light intensity. © 2005 The Optical Society of Japan