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1.
Raju ChL Gopal NO Narasimhulu KV Lakshmana Rao J Reddy BC 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(9):2181-2187
Electron paramagnetic resonance (EPR) studies have been carried out on Mn2+ ions doped in zinc malate trihydrate single crystals in the temperature range 123-413 K on X-band frequency. The EPR spectrum at room temperature exhibits a group of five fine structure transitions each splits into six hyperfine components. Angular variation studies reveal that Mn2+ ions enter the lattice substitutionally. From the observed EPR spectrum, the spin-Hamiltonian parameters have been evaluated. The variation of zero-field splitting parameter (D) with temperature is measured. From the optical absorption spectrum, the crystal field splitting parameter Dq and the Racah interelectronic repulsion parameters B and C have been evaluated. The infrared spectrum exhibits bands characteristic of the carboxylic acid salts. 相似文献
2.
The infrared spectra of 4-Cl 2-Me, 4-Cl 3-Me and 6-Cl 3-Me phenols have been recorded. The vibrational spectrum has been analysed
assuming that the molecules belong toC
s
point group and a tentative assignment of the observed frequencies to various modes of vibration has been proposed. The near
ultraviolet absorption spectrum of these compounds has also been recorded. Assuming the transition to be electronically allowed
the strongest band on the longer wavelength side has been assigned as the (0, 0) band in each case. The spectrum has been
analysed in terms of several excited state frequencies which have been correlated with the ground state frequencies observed
in the infrared spectrum. 相似文献
3.
Rozmanov DA Sizova OV Skripkin MY Burkov KA 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,62(1-3):92-96
The experimental Raman vibrational spectrum of the 5.94 m water solution of the beryllium(II) chloride has been acquired. Theoretical frequencies, infrared and Raman intensities of the vibrational spectrum of the beryllium cation tetrahydrate have been calculated by means of quantum chemical approach. The peaks of the experimental spectrum have been assigned on the basis of the results of the quantum-chemical calculations. It has been shown that the hydrating surrounding of the aquacation increases effectively the frequency of the beryllium-oxygen stretching vibration by 16% in comparison with the free complex. 相似文献
4.
The Raman spectrum from thin films of amorphous ice has been obtained by using a new laser beam trapping technique. Both the OH-stretching region of the spectrum and the always present intense scattering background have been interpreted. 相似文献
5.
The electronic absorption spectrum of thioformaldehyde has been recorded from 2200 to 1800 Å. Four electronic transitions have been identified in the spectrum and have been assigned to the π → π*, n → 4s, n → 4py and n → 4pz electron promotions. 相似文献
6.
Microwave spectra of the above-mentioned compounds have been partially assigned resulting in rotational constants, which have been interpreted in terms of conformers of the molecules. In the first two compounds three conformers have been found to contribute, only one of which can possibly be hydrogen-bonded. In the third two conformers appear to be present judging from the low-resolution spectrum. The high-resolution spectrum of one of these has been assigned. We believe that it is the hydrogen-bonded cis conformer in which the OH-group is sitting in a symmetrical position between two F-atoms. 相似文献
7.
Hongyang Zhao Jiyang Wang Huaijin Zhang Jing Li Guogang Xu Lili Yu Wenlan Gao Hairui Xia Robert I. Boughton 《Chemical physics letters》2008,450(4-6):274-280
Crystalline Nd:KLu(WO4)2 has been grown by the top-seeded-solution growth (TSSG) method. The polarized Raman spectrum, infrared spectrum, polarized absorption spectrum and fluorescence spectrum have been recorded at room temperature. The lattice vibration modes were calculated using space group theory and the infrared transmission spectrum was used as a supplement to the Raman spectrum to assign the modes more accurately. The Judd–Ofelt theory was used to study some important spectroscopic parameters, which were also compared with some other Nd3+ doped double tungstates. 相似文献
8.
Deva Prasad Raju B Lakshmana Rao J Narasimhulu KV Gopal NO Sunandana CS 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(9):2195-2198
EPR and optical absorption spectra of Cr3+ ions doped in KZnClSO4 x 3H2O single crystals have been studied at room temperature. The EPR spectrum exhibits a group of three fine structure transitions characteristic of Cr3+ ions. From the observed EPR spectra, the spin-Hamiltonian parameters have been determined. The optical absorption spectrum exhibits two broad bands characteristic of Cr3+ ions in an octahedral symmetry. From the observed band positions, the crystal field parameters have been evaluated. 相似文献
9.
四 (对羟基苯基 )卟啉 [T( 4 HP)P]具有共扼大π键及刚性平面 ,在 65 0nm左右产生纯的红色荧光 ,是一种较好的发光材料。依据 4 ( 2 甲基 丁氧基 )苯甲酚氧基 4′ 苯甲酰氧基苯基穴醚 [2 .2 ]具有液晶性[1 ] ,本文设计使T( 4 -HP)P的羟基进行酯化反应后生成的卟啉衍生物同时具有荧光和液晶性质 ,估计在发光材料特别是新近出现的圆偏光电致发光材料中具有潜在的应用[2 ] 。反应混合物通过柱色谱分离得到了酯化程度不同的几种卟啉衍生物。合成路线如下1 实验1 1 仪器及试剂Perkin Elmer1 70 0红外光谱仪 ,KBr压… 相似文献
10.
The NMR spectrum of π-cyclopentadienyl manganese tricarbonyl complex oriented in the liquid crystalline nematic phase has been studied. Values of the indirect spin couplings have been determined from the analysis of the spectrum. Information about the shape of the cyclopentadienyl moiety, the proton chemical shift anisotropy and molecular orientation has been obtained. 相似文献
11.
12.
Ichino T Gianola AJ Kato S Bierbaum VM Lineberger WC 《The journal of physical chemistry. A》2007,111(34):8374-8383
The 351.1 nm photoelectron spectrum of the vinyldiazomethyl anion has been measured. The ion is generated through the reaction of the allyl anion with N(2)O in helium buffer gas in a flowing afterglow source. The spectrum exhibits the vibronic structure of the vinyldiazomethyl radical in its electronic ground state as well as in the first excited state. Electronic structure calculations have been performed for these molecules at the B3LYP/6-311++G(d,p) level of theory. A Franck-Condon simulation of the X (2)A' state portion of the spectrum has been carried out using the geometries and normal modes of the anion and radical obtained from these calculations. The simulation unambiguously shows that the ions predominantly have an E conformation. The electron affinity (EA) of the radical has been determined to be 1.864 +/- 0.007 eV. Vibrational frequencies of 185 +/- 10 and 415 +/- 20 cm(-1) observed in the spectrum have been identified as in-plane CCN bending and CCC bending modes, respectively, for the X (2)A' state. The spectrum for the A (2)A' state is broad and structureless, reflecting large geometry differences between the anion and the radical, particularly in the CCN angle, as well as vibronic coupling with the X (2)A' state. The DFT calculations have also been used to better understand the mechanism of the allyl anion reaction with N(2)O. Collision-induced dissociation of the structural isomer of the vinyldiazomethyl anion, the 1-pyrazolide ion, has been examined, and energetics of the structural isomers is discussed. 相似文献
13.
The Raman spectrum of crystalline dibenzyl has been excited with a 50-mw He-Ne laser (6328 Å) and thirty one Raman bands have been recorded. The far infrared spec trum which reveals six absorptions in the 10–270 cm−1 region and the infrared spectrum from 300–3200 cm−1 have been observed, and correlations with the Raman frequencies have been established. Assignments of some of the characteristic frequencies have been made, and the implications of the data regarding the geometry of the molecule are discussed. 相似文献
14.
Devens Gust Thomas A. Moore David K. Luttrull Gilbert R. Seely Edith Bittersmann René V. Bensasson Michel Rougée Edward J. Land F. C. De Schryver M. Van der Auweraer 《Photochemistry and photobiology》1990,51(4):419-426
Tetraarylporphyrins substituted with nitro groups at beta-pyrrolic positions are potential candidates for electron-accepting pigments in model systems for photosynthesis. The photophysics of 2-nitro-5,10,15,20-tetra-p-tolylporphyrin and its zinc analog have been studied in order to evaluate this potential. The ground state absorption spectrum, the triplet-triplet absorption spectrum, the fluorescence emission spectrum, and associated photophysical parameters have been determined. The molecules have short singlet lifetimes and anomalous temperature- and solvent-dependent emission spectra which are consistent with the formation of an intramolecular charge transfer state of the type P+.-NO2-. in which the nitro group is twisted about its bond to the porphyrin, relative to the ground state conformation. 相似文献
15.
Barth A 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2000,56(6):1223-1232
A simple mathematical procedure--fine-structure enhancement--has been assessed on its ability to resolve overlapping bands in spectra. Its advantages and limitations have been explored using synthetic and experimental spectra. Fine-structure enhancement involves smoothing the original spectrum, multiplying the smoothed spectrum with a weighting factor and subtracting this spectrum from the original spectrum. As a result, the fine-structure of the original spectrum is enhanced in the processed spectrum and bands that overlap in the original spectrum appear as distinct bands in the processed spectrum. To be resolved by fine-structure enhancement, Lorentzian lines have to be separated by more than their quarter width at half maximum, Gaussian lines by more than their half width at half maximum. A comparison of fine-structure enhancement and Fourier self-deconvolution shows that Fourier self-deconvolution has in theory a higher potential to resolve overlapping bands. However, this depends crucially on the correct choice of the parameters. In practice, when parameters commonly used are chosen for Fourier self-deconvolution, fine-structure enhancement leads to similar results. This is demonstrated at the example of the infrared absorbance spectrum of the protein papain, where the amide I band components could be resolved similarly with both methods. Thus, fine-structure enhancement seems to be a simple alternative to Fourier self-deconvolution that does not require specialised software. 相似文献
16.
The vertical absorption spectra of phenanthrene and its radical cation have been studied theoretically by means of a multiconfigurational second-order perturbation approach. Singlet-singlet transition energies and oscillator strengths, and singlet-triplet excitation energies have been studied in the absorption spectrum of phenanthrene up to 6 eV. The absorption spectrum of the pehnanthrene radical cation has been computed up to 3.4 eV. The results obtained confirm previous assignments and also lead to new interpretations of the main features of the spectra of these systems. 相似文献
17.
18.
在RHF/6-31G^**,MP2/6-31G^**,B3LYP/6-31G^**水平下优化了5,6,9,10-四脱氢苯并环辛烯的平衡几何构型。用B3LYP/6-31G^**方法计算了该化合物的红外光谱、拉曼光谱、核磁共振谱。计算结果与实验结果吻合很好,从而在理论上证实了它的存在。用等键反应分析,自然键轨道方法对它的稳定性和共轭性分别进行了讨论。结果表明5,6,9,10-四脱氢苯并环辛烯分子平面刚性结构,可能稳定存在,但由于苯环共轭性的削弱和较高的张力,使得它易于分解。 相似文献
19.
Medhi RN Barman R Medhi KC Jois SS 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2000,(8):1523-1532
The ultraviolet absorption spectrum in the range 340-185 nm in the vapour and solution phase has been measured for 2-fluoro-5-bromopyridine. Three fairly intense band systems identified as the pi* <-- pi transitions II, III and IV have been observed. A detailed vibronic analysis of the vapor and solution spectra is presented. The first system of bands is resolved into about sixty-two distinct vibronic bands in the vapour-phase spectrum. The 0,0 band is located at 35944 cm(-1). Two well-developed progressions, in which the excited state frequencies nu'25 (283 cm(-1)) and nu'19 (550 cm(-1)) are excited by several quanta, have been observed. The corresponding excited state vibrational and anharmonicity constants are found to be omega'i = 292 cm(-1), x'ii = 4.5 cm(-1) (i = 25) and omega'i = 563.8 cm(-1), x'ii = 6.9 cm(-1) (i = 19). The other two band systems show no vibronic structure, the band maxima being located at 48346 and 52701 cm(-1), respectively. The oscillator strength of the band systems in different solutions and the excited state dipole moments associated with the first two transitions have been determined by the solvent-shift method. The infrared spectrum in the region 4000-130 cm(-1) and the laser Raman spectrum of the molecule in the liquid state have been measured and a complete vibrational assignment of the observed frequencies is given. A correlation of the ground and excited state fundamental frequencies observed in the UV absorption spectrum with the Raman or infrared frequencies is presented. 相似文献
20.
Maris A Giuliano BM Melandri S Ottaviani P Caminati W Favero LB Velino B 《Physical chemistry chemical physics : PCCP》2005,7(18):3317-3322
The rotational spectrum of 1-benzofuran has been investigated by three different rotational spectroscopy techniques: (i) millimeterwave absorption free jet spectroscopy, useful for a fast assignment of the spectrum; (ii) molecular beam Fourier transform microwave spectroscopy, sensitive to detect less abundant isotopic species in natural abundance; (iii) waveguide conventional microwave spectroscopy, useful for the study of intramolecular dynamics, through the rotational spectra of the vibrational satellites of low energy modes. Besides the rotational spectrum of the ground state of the normal species, the spectra of 9 singly substituted 13C and 18O isotopomers in natural abundance, and of 6 vibrational satellites, have been measured. Precise structural parameters for the molecule, as well as information on the potential energy surface of the low energy vibrations, have been obtained. The dipole moment components have been determined to be micro(a)= 0.216 (2) and micro(b)= 0.720 (3) D, respectively. 相似文献