bluuebunny/crossref_metadata_2025_split huggingface dataset:
Raman and infrared spectra, conformational stability and ab initio calculations for chlorocarbonyl isocyanate
Authors: Sullivan J. F. , Nandy S. K. , Lee Min Joo , Durig J. R. 
Published: May 2005

AbstractThe Raman (2500—10 cm−1) and infrared (2600—50 cm−1) spectra of chlorocarbonyl isocyanate, CIC(O)NCO, were recorded for the gas and solid. Additionally, the Raman spectrum of the liquid was recorded and qualitative depolarization values were obtained. The observed bands were assigned in terms of the more stable trans conformer (isocyanate grouptrans to the carbonyl bond) and less stable cis conformer. A conformer pair observed at 788 and 636 cm−1 in the Raman spectrum of the gas (775 and 634 cm−1 for the liquid) and assigned to the cis and trans COCI rock, respectively, was used to determine experimentally a ΔH value of 254 ± 48 cm−1 (726 ± 137 cal mol−1) and 230 ± 28 cm−1 (658 ± 80 cal mol−1) for the gas and liquid, respectively. In the far‐infrared spectrum of the gas, a series of three Q‐branches beginning at 83 cm−1 was observed and assigned to the fundamental torsional transition and two excited states transitions for the trans conformer. Using these three transitions and the experimentally determined ΔH value, a potential function was obtained for the interconversion of the two conformers with the following coefficients (in cm−1): V1 = −330 ± 50, V2 = 1025 ± 70, and V3 = 67 ± 40 and a trans to cis barrier of 1230 ± 150 cm−1 (3.52 ± 0.43 kcal mol−1) and a torsional frequency for the cis conformer of 69 ± 2 cm−1. The barrier to internal rotation and fundamental vibrational frequencies which were determined experimentally were compared with those obtained from ab initio Hartree—Fock gradient calculations utilizing the 6‐31G* basis set. These results are compared with some previous results on this molecule.
Vibrational spectra of NaBF4
Authors: Rajakumar V. , Krishnamurthy N. , Ramakrishnan V. , Kumar J. 
Published: May 2005

AbstractRaman spectra of an NaBF4 crystal were recorded and analysed. All the group theoretically expected bands were observed and assigned unambiguously. The rotational modes could be correlated with the principal moments of inertia of the BF4 − ion.
Resonant Raman excitation profile of the 220 cm−1 mode in trans‐azobenzene
Authors: Biancalana A. , Campani E. , Gorini G. , Masetti G. , Quaglia M. 
Published: May 2005

AbstractThe Raman excitation profile for the 220 cm−1 mode of trans‐azobenzene in cyclohexane solution was measured in resonance with the π‐π* transition peaked around 320 nm. A strong modulation of the band intensity across the first vibrational feature of the poorly resolved absorption spectrum was detected. The collected data were analysed by means of the time‐correlator theory and of a Franck‐Condon model to derive some molecular parameters of the excited electron state.
Surface‐enhanced Raman spectra of pyrazinecarboxamide and pyrazinecarbonitrile on silver sols
Authors: Arenas J. F. , Castro J. L. , Otero J. C. , Marcos J. I. 
Published: May 2005

AbstractAdsorption of pyrazinecarbonitrile and pyrazinecarboxamide on the metal surface in silver sols was investigated by the surface‐enhanced Raman Scattering (SERS) technique. Both molecules give similar spectra because the nitrile is converted into the amide by surface reaction. Pyrazinecarboxamide was found to adsorb via the substituent group with edge‐on orientation.
High‐resolution photoacoustic Raman spectroscopy of gases
Authors: Rotger M. , Lavorel B. , Chaux R. 
Published: May 2005

AbstractA high‐resolution photoacoustic Raman spectroscopy experiment is described. The resolution achieved by using two single‐mode pulsed lasers is about 0.0054 cm−1 (full width at half maximum intensity). The experiment was tested first on the v1/2v2 bands of CO2 and gave an increase of at least about one order of magnitude in the signal‐to‐noise ratio with respect to stimulated Raman spectroscopy at low pressure (ca. 10 Torr ≈ 1.3 kPa). The sensitivity is also demonstrated by the study of the weak hot band v1 + v2 — v2 of CO2. In both cases, the experimental line shape is well reproduced by taking into account Doppler and collisional effects. A comparison with CARS spectra was also made.
Resonance Raman spectroscopy of non‐planar nickel porphyrins
Authors: Shelnutt J. A. , Majumder S. A. , Sparks L. D. , Hobbs J. D. , Medforth C. J. , Senge M. O. , Smith K. M. , Miura M. , Luo L. , Quirke J. M. E. 
Published: May 2005

AbstractNon‐planar conformational distortions have recently been implicated in the biological activity of porphyrins and related tetrapyrroles in proteins, and several studies have used highly substituted porphyrins to model these nonplanar conformational distortions. Several aspects of non‐planarity in the highly substituted metalloporphyrins are discussed, focusing on resonance Raman spectroscopy as a technique for investigating these structural issues. First, different non‐planar distortions cause characteristic changes in the Raman spectrum. Specifically, the decreases in frequency of several Raman lines when compared with planar porphyrin analogs are shown to be similar for several classes of non‐planar highly substituted porphyrins. Second, the effect of the central metal ion [ M = Ni(II), Co(II), Cu(II), Zn(II), Co(III), Fe(III)] on the conformation of the sterically constrained non‐planar porphyrin octaethyltetraphenylporphyrin is considered. Responding to the conformational adjustments resulting from different metal size, the frequency of the structure‐sensitive Raman line v2 correlates with several structural parameters obtained from either mechanics calculations or crystallographic studies. The parameters include CβCβ bond length, core size and CαNCα angle. Finally, an effect of electron‐withdrawing substituents on the Raman frequencies is evident for the different classes of highly substituted porphyrins.
Mode‐specific relaxation dynamics of photoexcited fe(II) protoporphyrin IX in hemoglobin
Authors: Alden R. G. , Schneebeck M. C. , Ondrias M. R. , Courtney S. H. , Friedman J. M. 
Published: May 2005

AbstractThe behavior of the resonance Raman spectra of deoxyhemoglobin in the presence of strong resonant fields was studied by using ca. 30 ps laser pulses. The line width of the strongest Raman‐active mode in the Soret absorption band region, v4, broadens as a function of laser fluence, and its anti‐Stokes/Stokes intensity ratio is power dependent. Previous studies have suggested that equipartition of excess vibrational energy occurs on very fast time scales in the heme macrocycle subsequent to absorption of a photon. The mode‐specific vibrational dynamics of v4, however, indicate that the vibrational relaxation of the chromophore cannot be treated within the context of an equipartition of energy, but rather should be evaluated in terms of the relaxation phenomena of the specific vibrational mode. These data are evaluated in terms of relaxation mechanisms of the vibrational mode with reference to power‐broadening processes and transient vibrational population redistribution.
Mid‐ and low‐frequency Raman spectra of stable and metastable crystalline states of the 4‐n‐alkyl‐4′‐cyanobiphenyl (n = 9, 11, 12) liquid crystals
Authors: Perrot Michel , De Zen Jean‐Marc , Rothschild Walter G. 
Published: May 2005

AbstractMetastable crystalline states of each of the title compounds were reproducibly generated by rapid low‐temperature quenching of the corresponding liquids, as judged by the phonon‐like appearance of their low‐frequency Raman spectra (5–200 cm−1) and by a splitting of the mid‐Raman (ca. 2220 cm−1) CN stretch. Their observed aspects of peak frequencies, peak multiplicities and band widths differ markedly from those of the corresponding spectra of the stable crystals. We propose that the solid metastable configurations consist of packings or stacks of immobilized smectic‐like structures with significant long‐range positional order within each, but with disordered director orientations between them.
Surfactant‐aided surface‐enhanced Raman scattering of Zn(II), Co(II), Ni(II), Cu(II) and free‐base tetrakis(4‐sulphonatophenyl)porphyrins
Authors: Song Ok‐Keun , Shin Eun‐Joo , Lee Minyung , Kim Dongho , Han Joo‐Tak , Jee Jong‐Gi , Yoon Minjoong 
Published: May 2005

AbstractAlthough surface‐enhanced Raman scattering (SERS) has been recognized as a powerful tool for investigating the vibrational structure of molecules, the requirement that the molecules under study should have appropriate functional groups to interact with the metal surface has been a major problem in applying the SERS effect to many chemical or biological systems. It is shown that the introduction of a surfactant such as cetyltrimethylammonium bromide in a silver sol results in a strong Raman signal enhancement of negatively charged water‐soluble metallotetrakis(4‐sulphonatophenyl)porphyrins. Without introducing CTAB into a silver sol, these porphyrin molecules did not show any colour change and consequently no SERS effect was observed. Such a surfactant‐aided SERS effect will provide the possibility of applying SERS to new molecular systems.
CARS difference spectroscopy. I—theory for binary mixtures
Authors: Weippert A. , Kiefer W. 
Published: May 2005

AbstractThe theory for CARS difference spectroscopy is developed. This is an extension of linear Raman difference spectroscopy to non‐linear methods. This technique can be applied to the study of frequency shifts and band width changes in the CARS spectra of liquid mixtures or solutions when fluorescence does not allow linear Raman difference spectroscopy to be used. However, because of their coherent properties CARS spectra show complex line shapes due to interference effects between adjacent lines, which prohibits the simple subtraction of CARS spectra from one another. To make use of this technique, the spectra must be simulated with the inclusion of interference terms. The necessary theoretical treatment is outlined and some numerical model calculations for the v2(A1) Raman modes in chloroform‐deuterochloroform mixtures of different concentrations are given. Special emphasis is put on illustrating the influence of the interference effects in the CARS spectra of these mixtures.
Resonance Raman investigation of trans‐azobenzene in the lowest energy 1Au excited state
Authors: Biancalana A. , Campani E. , Di Domenico G. , Gorini G. , Masetti G. 
Published: May 2005

AbstractThe excitation profiles of several Raman bands of trans‐azobenzene solution in carbon tetrachloride were measured in resonance with the first allowed electronic transition peaked around 320 nm. The experimental results were analysed by means of a multi‐mode Franck–Condon model to obtain some excited state molecular parameters; such parameters were found to reproduce well the red side of the absorption band whereas some inconsistencies between experiment and calculation persist on the UV side. This has been tentatively explained as due to the contribution of a higher energy electronic state whose absorption band is peaked around 287 nm and which may slightly affect the parameters obtained.
Vibrational spectra of fluvalinate
Authors: Narayanan V. Anantha , Begun George M. , Stump Nathan A. , Stokes David L. , Vo‐Dinh Tuan 
Published: May 2005

AbstractThe normal Raman spectrum (NRS), Fourier transform infrared spectrum (FTIRS) and surface‐enhanced Raman spectrum (SERS) of the important insecticide and acaricide fluvalinate (C26H22ClF3N2O3) were recorded for the first time. The spectral data are discussed in terms of characteristic chemical group frequencies and bonds. The fingerprint regions of fluvalinate vibrations that are distinct in FTIRS are identified and presented with the different fingerprint frequencies that are only characteristic to NRS. The enhancement of the benzene ring‐breathing vibration of fluvalinate in SERS is a useful mode for trace analysis for residues of this pesticide at the subnanogram level. The vibrational spectra and polarization characteristics of NRS frequencies are useful as reference spectra for this pesticide in the qualitative analysis of its residues.
Anomalous frquency non‐coincidence effect in strongly interacting liquids, with special reference to molten salts
Authors: Kirillov Sviatoslav A. 
Published: May 2005

AbstractThe anomalous frequency non‐coincidence effect in strongly interacting liquids (ωiso < ωIR) was interpreted in terms of non‐resonant splitting caused by short‐range interparticle repulsion. The shift of the in‐phase component of the split lines was found to depend mainly on dsi/dQj, the derivative of the vibrational displacement of the ith atom with respect to the normal coordinat of jth vibration. For molten potassium thiocyanate, the numerical estimations agree well with the experimental data.
Spectroscopic studies of the thermochromism of N‐(2‐hydroxy‐4‐methoxybenzylidene)‐4‐nitroaniline
Authors: Takase Akira , Sakagami Sakumitsu , Nonaka Kazuhiro , Koga Toshiaki 
Published: May 2005

AbstractThermochromism of N‐(2‐hydroxy‐4‐methoxybenzylidene)‐4‐nitroaniline (HMBNA) was studied by Raman scattering and infrared absorption. HMBNA is yellow when freshly prepared and deepens to orange–red on heating above the melting point. On cooling at room temperature, the orange–red colour is retained for a few months. The change in colour is explained by the change in the molecular structure as indicated by the vibrational spectra. The spectra show that in the thermochromic coloured state the central group of HMBNA takes the cis‐keto amine form.
Micro‐Raman spectroscopy of sol–gel‐derived Pb(ZrxTi1 − x)O3 thin films
Authors: Agrawal D. C. , Majumder S. B. , Mohapatra Y. N. , Sathaiah S. , Bist H. D. , Katiyar R. S. , Ching‐Prado E. , Reynes A. 
Published: May 2005

AbstractThin films of ferroelectric PbZrxTi1 − xO3 were prepared by the sol–gel technique on sapphire and fused‐quartz substrates with thicknesses ranging from 0.6 to 1.2 μm. Powders of the above substance were also prepared by hydrolysis and condensation of the same precursor sol and crystallized by holding them at 600°C for either 6 or 12 h. From a comparison of the Raman spectra it is obvious that both powders and the film on sapphire substrate belong to the perovskite structure, whereas the film on fused quartz has a phyrochlore structure. These observations agree well with x‐ray measurements of diffraction patterns. Absence of 70 cm−1 E(TO) band in the film suggests that the film is rhombohedral with x being well above 0.535.
Continuum resonance Raman scattering in iodine: Time‐dependent calculations, scattering delay times and demonstration of fundamental principles
Authors: Ganz M. , Kiefer W. 
Published: May 2005

AbstractContinuum resonance Raman spectra of 127I2 were numerically simulated using time‐dependent quantum theory. The calculated spectra were compared with results obtained from traditional time‐independent calculations, based on the Kramers–Heisenberg–Dirac relationship, and experimental data obtained earlier by Strempel and Kiefer. A symmetry principle for corresponding Stokes and anti‐Stokes Raman spectra is also demonstrated and the corresponding spectra for this principle were simulated applying both time‐dependent and time‐independent theory. Further aspects such as the reflection principle and scattering delay times are discussed and compared with results obtained for 79Br2.
Preparation and vibrational spectroscopic characterization of copolymers of 2,3‐dimethylbutadiene and methyl methacrylate
Authors: Edwards H. G. M. , Johnson A. F. , Lewis I. R. , Ward N. J. , Wheelwright S. 
Published: May 2005

AbstractThe preparation and vibrational spectroscopic characterization of the hitherto unreported products of the copolymerization of 2,3‐dimethylbutadiene and methyl methacrylate are presented. The polymers were prepared by free radical polymerization using α,α′‐azobisisobutyronitrile as the initiator. Raman and Fourier transform infrared spectroscopic information on the 2,3‐dimethylbutadiene–methyl methacrylate copolymer is presented for a range of copolymers differing in the 2,3‐dimethylbutadiene to methyl methacrylate ratio. Quantitative information of the microstructure of the polymer and copolymer using the CC stretching vibrations is provided by Raman spectroscopy. Evidence is presented for the splitting of the CO stretching vibration, ascribed to aggregated syndiotactic and unaggregated syndio‐ and isotactic poly(methyl methacrylate) at 1734 and 1724 cm−1, respectively.
Conformational stability, barriers to internal rotation, vibrational assignments and Ab Initio calculations of 3‐methylbut‐1‐ene
Authors: Durig J. R. , Tang Qun , Little T. S. 
Published: May 2005

AbstractThe Raman spectra (3200–10 cm−1) of gaseous, liquid and solid and infrared spectra (3200–40 cm−1) of gaseous and solid 3‐methylbut‐1‐ene, H2CCHCH(CH3)2, were recorded. From the vibrational spectra of gaseous 3‐methylbut‐1‐ene, below 200 cm−1, the asymmetric torsional mode of the more stable trans and higher energy gauche conformers were assigned. From studies of the Raman spectrum of the gas with variable temperatures the trans conformer has been determined to be more stable than the gauche form by 155 ± 31 cm−1 [443 ± 89 cal mol−1 (1 cal = 4.184 J)]. Similar studies for the liquid indicate that the two conformers are nearly equivalent in energy and for the annealed solid only the gauche conformer persists. Optimized structural parameters, obtained from ab initio calculations with the MP2/6–31G basis set, were used to obtain the kinetic energy terms with structural relaxation for the asymmetric internal rotation. The coefficients of the potential function governing the conformational interchange are V1 = 198 ± 15, V2 = 68 ± 6, V3 = 748 ± 1 and V4 = ‐55 ± 2 cm−1, and this potential has trans to gauche, gauche to gauche and gauche to trans barriers of 816, 787 and 657 cm−1, respectively. Barriers to internal rotation of the methyl rotors of 1169 cm−1 for the trans conformer and 1290 ± 30 and 1525 ± 50 cm−1 for the gauche conformer were determined from the low‐frequency Raman and far‐infrared spectra of the gas. Vibrational assignments are provided which are based on infrared band contours. Raman depolarization values, group frequencies and normal coordinate calculations. The conformational stabilities, barriers to internal rotation and fundamental vibrational frequencies which were determined from experimental data are compared with those obtained from ab initio calculations.
Raman, infrared and NMR spectra, conformational stability and ab initio calculations of trimethoxyborane
Authors: Stampf E. J. , Kim Young H. , Durig J. R. 
Published: May 2005

AbstractThe Raman spectra (3500–20 cm−1) of gaseous, liquid and solid and the infrared spectra (4000–50 cm−1) of gaseous and solid trimethoxyborane, B(OCH)3, were recorded. Qualitative depolarization values were obtained from the Raman spectrum of the liquid. All normal modes, except the torsions, were assigned based on infrared band contours, depolarization values, group frequencies and normal coordinate calculations. From a comparison of the spectra in the fluid states with that from the solid, it is concluded that the molecule exists predominantly in a single conformation in all physical states. Frequencies and potential energy distributions for the normal modes were calculated with the force constants obtained from ab initio calculations with the 3–21G basis set. A comparison of these calculated frequencies with the observed spectra is consistent with the predominant form having a ‘planar’ heavy atom skeleton with C3h symmetry. In was not possible to determine an experimental barrier to rotation about the BO bond. No change was observed in the 13C NMR spectrum over the temperature range of 22 to −90°C. Structural parameters, conformational stability and barriers to internal rotation were obtained from ab initio Hartree–Fock gradient calculations employing both the 3–21G and 6–31G* basis sets. The results are compared with the corresponding data for some similar organoboranes.
SERS investigation of the co‐adsorption of nicotinic acid and 3‐acetylpyridine on silver electrodes
Authors: Barthelmes J. , Pofahl G. , Panagiotakis M. , Plieth W. 
Published: May 2005

AbstractThe pH‐dependent solution Raman spectra of nicotinic acid and 3‐acetylpyridine are reported in the wavenumber range 500–1750 cm−1. The changes with pH in the spectra of both molecules were correlated with the structure of the predominant solution species. Band assignments were carried out by referring to the spectra of the pure compounds and of related molecules. The surface‐enhanced Raman spectra of nicotinic acid and 3‐acetylpyridine co‐adsorbed on polycrystalline silver electrodes were measured as a function of applied potential. The surface‐active species were identified according to the solution and surface Raman shifts of the individual components. A surface configuration involving the interaction of nicotinic acid and 3‐acetylpyridine is proposed to explain the observed spectra.
Raman frequency amplification in an erbium‐doped optical waveguide
Authors: Pavlov L. I. , Ivanov L. M. 
Published: May 2005

AbstractOptical amplification in an erbium‐doped fibre, pumped by an argon ion laser, was investigated. Spontaneous Raman frequency generation arising from an InGaAsP Fabry–Perot‐type picosecond laser signal directed into the optical waveguide and also high amplification of the Raman components in a strongly doped fibre were produced. These have not been observed previously. A great increase in the intensity of the fundamental soliton pulse when propagation in optical fibres with length of tens of centimetres was also observed.
Vibrational study of nicotinic acid complexes with different central ions
Authors: Lewandowski Włodzimierz , Barańska Halina , Mościbroda Piotr 
Published: May 2005

AbstractAssignments are proposed for the IR and Raman spectra of potassium, zinc and mercury(II) nicotinates and for the UV‐visible spectra of the f → f transition for erbium nicotinate. The influence of K, Zn, Hg(II), Nd(III), Dy(III) and Er(III) on the aromatic system of nicotinic acid was studied. There are essential differences in the number, wavenumber and intensity of aromatic system bands in the ranges of the ring modes, (1610–1400 cm−1), γ(CH) (970–700 cm−1) and Φ(CC) (700–650 cm−1), depending on the central ion. Potassium and mercury(II) perturb but lanthanides stabilize the aromatic system of nicotinic acid. The wavenumbers and intensities of some vibrational bands of the aromatic system depend systematically on the ionic potentials of the metals.
Fourier transform Raman spectroscopy of some energetic materials and propellant formulations
Authors: McNesby K. L. , Wolfe J. E. , Morris J. B. , Pesce‐Rodriguez R. A. 
Published: May 2005

AbstractFourier transform Raman (FTR) spectroscopy employing near‐IR laser radiation at 1.06 μm as the scattering source was used to obtain Raman spectra of some neat energetic materials and several propellant formulations containing those energetic materials. It is shown that only crystalline components of propellant formulations are easily detected by FTR spectroscopy. Also, FTR spectroscopy is shown to be a useful tool in determining the principle ingredient(s) in many non‐colored propellant formulations.