Spectrochimica acta. Part A: Molecular spectroscopy最新文献

{"title":"Papers in press","authors":"","doi":"10.1016/0584-8539(94)80192-4","DOIUrl":"https://doi.org/10.1016/0584-8539(94)80192-4","url":null,"abstract":"","PeriodicalId":82782,"journal":{"name":"Spectrochimica acta. Part A: Molecular spectroscopy","volume":"50 13","pages":"Pages i-iii"},"PeriodicalIF":0.0,"publicationDate":"1994-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0584-8539(94)80192-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91737694","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental investigation of excited state electron transfer reactions between some bicyclic molecules and tetracyanoquinodimethane (TCNQ)","authors":"R. De,&nbsp;S. Bhattacharyya ,&nbsp;T. Ganguly","doi":"10.1016/0584-8539(93)E0035-U","DOIUrl":"https://doi.org/10.1016/0584-8539(93)E0035-U","url":null,"abstract":"<div><p>Investigations on photoinduced electron transfer (ET) reactions between excited (ground) bicyclic electron donors 5,6,7,8-tetrahydro-2-naphthol (TH2N), 2-methoxy-5,6,7,8-tetrahydro naphthalene (2MTHN) and ground state (excited) acceptor tetracyanoquinodimethane (TCNQ) in fluid solutions of different polarity at the ambient temperature (300 K) by electronic absorption, steady state fluorescence and time-resolved spectroscopic methods in the time domain of nanosecond order have been carried out. It is suggested that in highly polar solvent acetonitrile (ACN), a loosely-structured transient geminate ion-pair complex (GIP) in the excited singlet state (<em>S</em>₁) is formed due to the ET encounter between the present donor TH2N or 2MTHN and TCNQ and this GIP complex rapidly dissociates into stable excited radical ions, as evidenced from steady state spectra. In polar DMF solvents, TCNQ exhibits an electronic absorption band of its anion without the presence of donor molecules. Both steady state and time-resolved data indicate that ET reactions between the present donors and acceptor TCNQ are largely impeded in the less polar solvent tetrahydrofuran (THF). In the highly polar solvent ACN, ET reactions between the donors and acceptor TCNQ have been suggested to be of adiabatic or intermediate between adiabatic and non-adiabatic types, from the observation of radical ion species in the electronic excited state. For some bicyclic donors and TCNQ acceptor systems, large negative Δ<em>G</em>, which is a measure of the gap between locally excited and radical ion-pair states, shows reaction occurs in highly exothermic regions. Further observations of −Δ<em>G</em>&gt;λ, nuclear reorganization energy parameters and the decrement of ET rate (<em>k</em>_ET) with increasing exothermicity (more negative Δ<em>G</em> values) suggest the ET reaction for the bicyclic donor—TCNQ acceptor systems studied in the present investigation might occur in the Marcus inverted region. The possibility of building up efficient photoconducting materials with the present donor acceptor systems is suggested.</p></div>","PeriodicalId":82782,"journal":{"name":"Spectrochimica acta. Part A: Molecular spectroscopy","volume":"50 13","pages":"Pages 2155-2165"},"PeriodicalIF":0.0,"publicationDate":"1994-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0584-8539(93)E0035-U","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91767781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Integrated absorption intensities of haloethanes and halopropanes","authors":"Marilyn P. Olliff,&nbsp;Gad Fischer","doi":"10.1016/0584-8539(93)E0027-T","DOIUrl":"https://doi.org/10.1016/0584-8539(93)E0027-T","url":null,"abstract":"<div><p>The infrared absorption intensities of the chlorofluorocarbons C₂Cl<em>_x</em>F<em>_y</em>, (<em>x</em> + <em>y</em> = 6); the hydrofluorocarbons C₂H<em>_x</em>F<em>_y</em>H (<em>x</em> + <em>y</em> = 6); and a number of hydrochlorofluorocarbons, including some members of the propane series, have been measured. Absorption intensities have been obtained by integration over specified ranges of frequencies. The ranges used include the atmospheric window (1250t-833 cm⁻¹), 3500-450 cm⁻¹, 1300-700 cm⁻¹, and those for selected individual absorption bands. Comparisons of the results have been made with published work where available, and attention is drawn to possible sources of error in the measurement of band areas. The spectra of the halopropanes have been included for the range 3500-150 cm⁻¹. A preliminary study has been made of the relation between the number of fluorine atoms in the molecule and the intensity of absorption of the CF stretching vibrations.</p></div>","PeriodicalId":82782,"journal":{"name":"Spectrochimica acta. Part A: Molecular spectroscopy","volume":"50 13","pages":"Pages 2223-2237"},"PeriodicalIF":0.0,"publicationDate":"1994-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0584-8539(93)E0027-T","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91767782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Variable-temperature 13C solid-state NMR spectra: Mobility of trimethyltin groups in coordination polymers of the type [(Me3Sn)4M(CN)6]∞ (MFe, Os, Ru)","authors":"Robin K. Harris,&nbsp;M.Maral Sünnetçioğlu ,&nbsp;R.Dieter Fischer","doi":"10.1016/0584-8539(93)E0020-W","DOIUrl":"10.1016/0584-8539(93)E0020-W","url":null,"abstract":"<div><p>Solid-state ¹³C CP MAS NMR studies of compounds [(Me₃Sn)₄M(CN)₆]∞ with MFe, Ru and Os were performed over a temperature range of 80 K in order to understand exchange thermodynamics. For each compound six methyl carbon signals are seen below 240 K, showing there are two non-equivalent Me₃Sn units. Using detailed lineshape analysis the thermodynamic activation parameters for the three samples were obtained. Low-temperature 2-D exchange spectra indicated that exchange occurs between the carbons of each Me₃Sn rotor independently. Therefore in the calculations a model of two independent three-site mutual-exchange processes was used. The effect of ^117/119Sn satellites was included.</p></div>","PeriodicalId":82782,"journal":{"name":"Spectrochimica acta. Part A: Molecular spectroscopy","volume":"50 12","pages":"Pages 2069-2078"},"PeriodicalIF":0.0,"publicationDate":"1994-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0584-8539(93)E0020-W","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72974417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vibrational spectroscopic and force field studies of organorhenium(VII) trioxides—I. Methyltrioxorhenium(VII), ethyltrioxorhenium(VII) and (n-propyl)trioxorhenium(VII)","authors":"J. Mink ,&nbsp;G. Keresztury ,&nbsp;A. Stirling ,&nbsp;W.A. Herrmann","doi":"10.1016/0584-8539(93)E0024-Q","DOIUrl":"10.1016/0584-8539(93)E0024-Q","url":null,"abstract":"<div><p>The infrared absorption spectra of the alkyltrioxorhenium(VII) compounds, methyl-, ethyl-, and (<em>n</em>-propyl)trioxorhenium(VII) have been recorded and analyzed. The Raman spectrum could be obtained for the methyl compound, for which the IR and Raman spectra of a perdeuterated sample (CD₃ReO₃) were also examined. Full vibrational assignment is proposed for all three molecules. The band assignments were based on comparison with the spectra of similar molecules (e.g. alkylmercury halides) and supported or improved by normal coordinate analysis. For the CH₃ReO₃, a hybrid orbital force field (HOFF) was used while for C₂H₅ReO₃ and (<em>n</em>-CH₃H₇)ReO₃ a common simplified valence force field was obtained from an overlay calculation. The influence of size and conformation of the alkyl group on the vibrations of the ReO₃ moiety is discussed.</p></div>","PeriodicalId":82782,"journal":{"name":"Spectrochimica acta. Part A: Molecular spectroscopy","volume":"50 12","pages":"Pages 2039-2057"},"PeriodicalIF":0.0,"publicationDate":"1994-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0584-8539(93)E0024-Q","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74992000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optical absorption enhancement of CdS nanometer crystallites","authors":"Ying Wang,&nbsp;Yinsheng Wang,&nbsp;Yujin Wang,&nbsp;Kai Huang,&nbsp;Tianjin He,&nbsp;Fan-Chen Liu","doi":"10.1016/0584-8539(93)E0030-Z","DOIUrl":"https://doi.org/10.1016/0584-8539(93)E0030-Z","url":null,"abstract":"<div><p>An elementary model and analytical theory on optical absorption enhancement phenomena with decreasing the nanometer crystallite size is proposed by using the effective mass theory of excitons and taking into account the tunneling effect and the frequency change. With decreasing particle size, the confinement imposed on the relative motion of electron—hole pair enhances the oscillator strength, and the change of transition frequency due to the size quantization blue shift weakens the oscillator strength. For larger band gap materials, the former is dominant, thus the absorption coefficient tends to enhancement as the particle size decreases. Good agreement between the theoretical and the experimental absorption coefficient of CdS is achieved.</p></div>","PeriodicalId":82782,"journal":{"name":"Spectrochimica acta. Part A: Molecular spectroscopy","volume":"50 13","pages":"Pages 2203-2213"},"PeriodicalIF":0.0,"publicationDate":"1994-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0584-8539(93)E0030-Z","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91737689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A laser Raman spectroscopy study of molybdenum oxide supported on alumina and titania","authors":"M. Del Arco,&nbsp;S.R.G. Carrazán,&nbsp;C. Martín,&nbsp;V. Rives,&nbsp;J.V. García-Ramos,&nbsp;P. Carmona","doi":"10.1016/0584-8539(93)E0029-V","DOIUrl":"https://doi.org/10.1016/0584-8539(93)E0029-V","url":null,"abstract":"<div><p>Molybdenum oxide supported on alumina and titania prepared by three different methods (impregnation, calcination and hydrothermal treatment of mechanical mixtures), have been studied by laser Raman spectroscopy. Different oxomolybdenum species have been detected depending on the method of preparation and on the calcination conditions. Heptamolybdate and polymolybdate species were found in the impregnated and in the uncalcined, hydrothermally treated samples supported on alumina and titania, respectively, whereas polymolybdate species were formed on the surface of alumina when the mechanical mixtures and the hydrothermally treated samples were calcined in the presence of water vapour. However, two kinds of species, polymolybdate and mono-oxomolybdenum, were found in the case of the mechanical mixtures and the hydrothermally treated samples calcined in the presence of water vapour when supported on titania.</p></div>","PeriodicalId":82782,"journal":{"name":"Spectrochimica acta. Part A: Molecular spectroscopy","volume":"50 13","pages":"Pages 2215-2221"},"PeriodicalIF":0.0,"publicationDate":"1994-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0584-8539(93)E0029-V","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91767783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Kramers—Kronig analysis of infrared reflection spectra with parallel polarization for isotropic materials","authors":"Kiyoshi Yamamoto,&nbsp;Hatsuo Ishida","doi":"10.1016/0584-8539(93)E0019-S","DOIUrl":"10.1016/0584-8539(93)E0019-S","url":null,"abstract":"<div><p>Kramers—Kronig analysis of reflection spectra from a single interface with parallel (<em>p</em>) polarization has been developed by using non-linear least square refinement and its application is studied theoretically with regard to a phase correction term. The errors in phase shift and complex refractive index obtained by Kramers—Kronig analysis have been examined for such techniques as external and total internal reflection spectroscopies by using spectral simulation with model spectra composed of complex refractive indices based on dispersion theory. From these calculations, it has been shown that the complex refractive index can be obtained for isotropic samples by Kramers—Kronig analysis using <em>p</em> polarization with the same accuracy as for perpendicular (<em>s</em>) polarization. The combination of Kramers—Kronig analysis for each polarization allows one to obtain the complex refractive index of anisotropic materials. Furthermore, the complex refractive index of thin film samples on metal can be obtained from reflection-absorption spectroscopy (RAS) by Kramers—Kronig analysis including a non-linear least square refinement procedure.</p></div>","PeriodicalId":82782,"journal":{"name":"Spectrochimica acta. Part A: Molecular spectroscopy","volume":"50 12","pages":"Pages 2079-2090"},"PeriodicalIF":0.0,"publicationDate":"1994-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0584-8539(93)E0019-S","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80752347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Long-range superexchange interaction in copper(II)-dimers: A quantum mechanical calculation","authors":"C. Erasmus,&nbsp;W. Haase","doi":"10.1016/0584-8539(93)E0032-R","DOIUrl":"https://doi.org/10.1016/0584-8539(93)E0032-R","url":null,"abstract":"<div><p>Self consistent field-Møller-Plesset (SCF-MP) calculations have been performed to reproduce the experimentally observable exchange interaction <em>J</em> as a function of long distances in Cu-dimers. Four models with different extended bridging ligands were chosen to cover a Cu(II)Cu(II) separation of <em>ca.</em> 7.0–11.0 Å. The calculated <em>J</em> values fit the limiting function of R.E. Coffman and G.R. Buettner (<em>J. Phys. Chem.</em> <strong>18</strong>, 2387 (1979)] very well. Nevertheless the tendency of the <em>J</em> values was discussed rather than their absolute values. The reasons for the relatively strong measured exchange interaction of 2<em>J</em> = −140 cm⁻¹ for <strong>H</strong> = −2<em>J</em>₁₂<em>S</em>₁<em>S</em>₂ for the same terephthalato-bridged Cu(II)Cu(II) dimers with a CuCu separation of 11.25 Å were discussed.</p></div>","PeriodicalId":82782,"journal":{"name":"Spectrochimica acta. Part A: Molecular spectroscopy","volume":"50 13","pages":"Pages 2189-2195"},"PeriodicalIF":0.0,"publicationDate":"1994-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0584-8539(93)E0032-R","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90128761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Concentration dependence of the relative error in diffuse reflectance infrared spectrometry","authors":"Z. Krivácsy,&nbsp;J. Hlavay","doi":"10.1016/0584-8539(93)E0031-Q","DOIUrl":"10.1016/0584-8539(93)E0031-Q","url":null,"abstract":"<div><p>A mathematical model between the relative error in the Kubelka—Munk (K—M) function and the sample concentration has been determined if the K—M function is linear with the sample concentration, <em>c</em>≤ w/w%. The theoretical model has been investigated by measuring 3–5 parallels at different sample concentrations and calculating the RSD for the selected absorption bands. Quartz (<em>d</em>_ave = 1.3 μm) and calcite (<em>d</em>_ave = 3.3 μm) as analytes and KBr (<em>d</em>_ave = 9.9 μm) as embedding material were used. The result of the model and the experiments were in a good agreement. It has been shown that the RSD for absorption bands with small sensitivity can increase up to ±20–60%. The precision of the quantitative analysis in diffuse reflectance infrared Fourier transform spectrometry (DRIFTS) can be improved by applying more sensitive absorption bands and parallel measurements at one standard concentration</p></div>","PeriodicalId":82782,"journal":{"name":"Spectrochimica acta. Part A: Molecular spectroscopy","volume":"50 13","pages":"Pages 2197-2202"},"PeriodicalIF":0.0,"publicationDate":"1994-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0584-8539(93)E0031-Q","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80923294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}