共查询到20条相似文献,搜索用时 390 毫秒
1.
Jose P. Abraham D. Sajan Joseph Mathew I. Hubert Joe V. George V. S. Jayakumar 《Journal of Raman spectroscopy : JRS》2008,39(12):1821-1831
The oroxylin, 5,7‐dihydroxy 6‐methoxy flavone is a potent natural product extracted from ‘Vitex peduncularis’. Density functional theory (DFT) at B3LYP/6‐311G(d,p) level has been used to compute energies of different conformers of oroxylin to find out their stability, the optimized geometry of the most stable conformer and its vibrational spectrum. The conformer ORLN‐1 with torsion angles 0, 180, 180 and 0 degrees, respectively, for H13 O12 C6 C5, H14 O10 C4 C5, H13 O12 C6 C5 and H14 O10 C4 C5 is found to be most stable. The optimized geometry reveals that the dihedral angle φ between phenyl ring B and the chrome part of the molecule in − 19.21° is due to the repulsive force due to steric interaction between the ortho‐hydrogen atom H29 of the B ring and H18 of the ring C (H29·H18 = 2.198 Å). A vibrational analysis based on the near‐infrared Fourier transform(NIR‐FT) Raman, Fourier transform‐infrared (FT‐IR) and the computed spectrum reveals that the methoxy group is influenced by the oxygen lone pair‐aryl pz orbital by back donation. Hence the stretching and bending vibrational modes of the methoxy group possess the lowest wavenumber from the normal values of methyl group. The carbonyl stretching vibrations have been lowered due to conjugation and hydrogen bonding in the molecules. The intramolecular H‐bonding and nonbonded intramolecular interactions shift the band position of O10 H14 and O12 H13 stretching modes, which is justified by DFT results. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
2.
Jian‐Li Guo Chong Liu Bin‐Bin Xie Yan‐Ying Zhao Ke‐Mei Pei Hui‐Gang Wang Xuming Zheng Yue‐Jie Ai Xue‐Bo Chen Wei‐Hai Fang Chi Shun Yeung 《Journal of Raman spectroscopy : JRS》2012,43(10):1477-1486
The photophysics and photochemistry of pyrazine (C4H4N2, D2h) after excitation to the S2 (1 1B2u, 1ππ*) electronic state were studied by using the resonance Raman spectroscopy and complete active space self‐consistent field method calculations. The B‐band resonance Raman spectra in cyclohexane solvent were obtained at 266.0, 252.7, and 245.9 nm excitation wavelengths to probe the structural dynamics of pyrazine in the S2 (1 1B2u, 1ππ*) state. Three electronic states 1 1B3u, 1 1B1g, and 1 1B2g were found to couple with the S2 (1 1B2u, 1ππ*) state. Two conical intersection (CI) points CI[S2(B2u)/S1(B3u)] and CI[S1/S0] and one transition state of the isomerization between pyrazine and pyrimidine were predicted to play important roles in the photochemistry of pyrazine. On the basis of the calculations, the mechanism of the photoisomerization reaction between pyrazine and pyrimidine has been proposed. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
3.
Hirotsugu Hiramatsu Noriko Miki Hideo Takeuchi 《Journal of Raman spectroscopy : JRS》2010,41(12):1708-1713
Histidine is an important and versatile amino acid residue that plays a variety of structural and functional roles in proteins. Although the Raman bands of histidine are generally weak, histidine in the N‐deuterated cationic form with imidazole Nπ D and Nτ D bonds (N‐deuterated histidinium) gives two strong Raman bands assignable to the C4C5 stretch (νCC) and the Nπ C2 Nτ symmetric stretch (νNCN) of the imidazole ring. We examined the Raman spectra of N‐deuterated histidinium in 12 crystals with known structures. The observed νCC and νNCN wavenumbers were analyzed to find empirical correlations with the conformation and hydrogen bonding. The effect of conformation on the vibrational wavenumber was expressed as a threefold cosine function of the Cα Cβ C4C5 torsional angle. The effect of hydrogen bonding at Nπ or Nτ was assumed to be proportional to the inverse sixth power of the distance between the hydrogen and acceptor atoms. Multiple linear regression analysis clearly shows that the conformational effect on the vibrational wavenumber is comparable for νCC and νNCN. The hydrogen bond at Nπ weakly lowers the νCC wavenumber and substantially raises the νNCN wavenumber. On the other hand, the hydrogen bond at Nτ strongly raises the νCC wavenumber but does not affect the νNCN wavenumber. These empirical correlations may be useful in Raman spectral analysis of the conformation and hydrogen bonding states of histidine residues in proteins. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
4.
Marcelo M. Campos‐Vallette Nancy P. Chandía Ernesto Clavijo David Leal Betty Matsuhiro Igor O. Osorio‐Romn Simonet Torres 《Journal of Raman spectroscopy : JRS》2010,41(7):758-763
The surface‐enhanced Raman scattering (SERS) of sodium alginates and their hetero‐ and homopolymeric fractions obtained from four seaweeds of the Chilean coast was studied. Alginic acid is a copolymer of β‐D ‐mannuronic acid (M) and α‐L guluronic acid (G), linked 1 → 4, forming two homopolymeric fractions (MM and GG) and a heteropolymeric fraction (MG). The SERS spectra were registered on silver colloid with the 632.8 nm line of a He Ne laser. The SERS spectra of sodium alginate and the polyguluronate fraction present various carboxylate bands which are probably due to the coexistence of different molecular conformations. SERS allows to differentiate the hetero‐ and homopolymeric fractions of alginic acid by characteristic bands. In the fingerprint region, all the poly‐D ‐mannuronate samples present a band around 946 cm−1 assigned to C O stretching, and C C H and C O H deformation vibrations, a band at 863 cm−1 assigned to deformation vibration of β‐C1 H group, and one at 799–788 cm−1 due to the contributions of various vibration modes. Poly‐L ‐guluronate spectra show three characteristic bands, at 928–913 cm−1 assigned to symmetric stretching vibration of C O C group, at 890–889 cm−1 due to C C H, skeletal C C, and C O vibrations, and at 797 cm−1 assigned to α C1 H deformation vibration. The heteropolymeric fractions present two characteristic bands in the region with the more important one being an intense band at 730 cm−1 due to ring breathing vibration mode. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
5.
Resonant with the CS π → π* electronic transition, the intensity of CS stretching and its overtone have been greatly enhanced in the 488‐ and 319‐nm excited resonance Raman spectra. The isotropic and anisotropic parts of the Raman spectra of CS stretching modes of ethylene trithiocarbonate (ET) at different concentrations have been analyzed in order to study the noncoincidence effect (NCE). In neat ET, the experimentally measured values of noncoincidence Δυnc are ~4.60 cm−1 for the CS stretching modes, which reduce to 1.30 cm−1 at the mole fraction χm (ET) = 0.13. Both the isotropic and anisotropic peak frequencies of CS stretching were found to shift to higher wavenumber when the concentrations are diluted, while the value of Δυnc goes on decreasing upon dilution. The absolute Raman cross section of carbonyl stretching was also measured, and their behavior was unusual (first increasing and then decreasing with the decrease of concentration). The experimental result shows that there may exist self‐association in the high concentration, and the main NCE mechanism may be due to the transition dipole–transition dipole coupling between the ET molecules. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
6.
Zhu‐Bing Xu Sheng Pan Yi Yang Jia‐Dan Xue Xuming Zheng Bin‐Bin Xie Wei‐Hai Fang 《Journal of Raman spectroscopy : JRS》2014,45(6):438-447
The photophysics of 3‐methyl‐3‐pentene‐2‐one (3M3P2O) after excitation to the S2(ππ*) electronic state were studied using the resonance Raman spectroscopy and complete active space self‐consistent field (CASSCF) method calculations. The A‐band resonance Raman spectra were obtained in cyclohexane, acetonitrile, and methanol with excitation wavelengths in resonance with the first intense absorption band to probe the structural dynamics of 3M3P2O. The B3LYP‐TD/6‐31++G(d, p) computation was carried out to determine the relative A‐band resonance Raman intensities of the fundamental modes, and the result was used to reproduce the corresponding fundamental band intensities of the 223.1 nm resonance Raman spectrum and thus to examine whether the vibronic‐coupling existed in Franck‐Condon region or not. CASSCF calculations were carried out to determine the minimal singlet excitation energies of S1, FC, S1,min (nπ*), S2, FC, S2,min (ππ*), the transition energies of the conical intersection points Sn/Sπ, Sn/S0, and the optimized excited state geometries as well as the geometry structures of the conical intersection points. The A‐band short‐time structural dynamics and the corresponding decay dynamics of 3M3P2O were obtained by the analysis of the resonance Raman intensity pattern and CASSCF computations. It was revealed that the initial structural dynamics of 3M3P2O was towards the simultaneous C3=C4 and C2=O7 bond elongation, with the C3=C4 bond length lengthening greater at the very beginning, whereas the C2=O7 bond length changing greater at the later evolution time before reaching the CI(S2/S1) conical intersection point. The decay dynamics from S2(ππ*) to S1(nπ*) via S2(ππ*)/S1(nπ*) in singlet realm and from S1(nπ*) to T1(nπ*) via ISC[S1(nπ*)/T2(ππ*)/T1(nπ*)] in triplet realm are proposed. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
7.
The vibronic coupling between the first excited S1 (21Ag) and the second excited S2 (11Bu) singlet electronic states in spectroscopy of trans‐1,3,5‐hexatriene molecule is investigated on the basis of a model consisting of two electronic states coupled by two vibrational modes. Employing a perturbation theory that treats the intramolecular couplings in a perturbative manner, the absorption and resonance Raman cross sections and excitation profiles of this molecule are calculated using the time‐correlation function formalism. The non‐Condon corrections are included in evaluation of cross sections. The multidimensional time‐domain integrals that arise in these calculations have been evaluated for the case in which S0 (11Ag) S2 (11Bu) electronic transition takes place between displaced and distorted harmonic potential energy surfaces. The calculated spectra are in good agreement with the experimental ones. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
8.
M. Kalinowska R. ?wis?ocka Z. Rz?czyńska J. Sienkiewicz W. Lewandowski 《Journal of Physical Organic Chemistry》2010,23(1):37-47
In order to understand the nature of the interactions of biologically important ligands, it is necessary to carry out the physico‐chemical studies of these compounds with their biological targets (e.g., receptors in the cell or important cell components). Results of this study make it possible to predict some properties of a molecule, such as its reactivity, durability of complex compounds, and kinship to enzymes. In this paper the effect of alkali metal cations (Li, Na, K, Rb, and Cs) on the electronic structure of m‐methoxybenzoic acid (m‐anisic acid) was studied. The experimental IR (in solid state and solution), Raman, UV (in solid state and solution), 1H, and 13C NMR spectra of m‐methoxybenzoic acid, and its salts were registered, assigned, and analyzed. Some of the obtained results were compared with published data for o‐anisic acid and o‐anisates. The structures of anisic acid and Li, Na, and K m‐anisates were optimized at the B3LYP/6‐311++G** level. The IR, 1H, and 13C NMR spectra and NPA, ChelpG, and MK atomic charges were calculated. The change of metal along with the series: Li → Na → K → Rb → Cs caused: (1) the change in the electronic charge distribution in anisate anion that is seen via the occurrence of the systematic shifts of several bands in the experimental and theoretical IR and Raman spectra of anisates; (2) systematic 1H and 13C NMR chemical shifts; (3) hypsochromic shifts in UV spectra of salts as compared to ligands. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
9.
LiBo Wang Wenfei Zhang Shaosong Shen Huigang Wang Xuming Zheng Anmin Zheng Yueying Chu 《Journal of Raman spectroscopy : JRS》2012,43(10):1465-1471
Excitation wavelengths of 282.4, 273.9 (A band), 252.7, 239.5 and 228.7 nm (B band) resonance Raman spectra were acquired for di‐2‐pyridylketone, and density functional calculations were carried out to help in the elucidation of the photo relaxation dynamics of A‐band and B‐band electronic transitions. The resonance Raman spectra show that the intensity pattern of the A band presents great difference from that of the B band, which indicate that the short‐time A‐band (S0→S4) photo relaxation dynamics have substantial difference from that of B band (S0→S10) . The overall picture of short‐time dynamics and the vibronic coupling mechanisms are interpreted using Albrecht's theory. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
10.
Dan Li Yan Ying Zhao Jia‐Dan Xue Xuming Zheng 《Journal of Raman spectroscopy : JRS》2015,46(3):293-301
The short‐time structural dynamics of 4‐formaldehyde imidazole and imidazole in light absorbing S2(ππ*) state were studied by using resonance Raman spectroscopy and quantum mechanical calculations. The vibrational spectra and ultraviolet absorption spectra of 4‐formaldehyde imidazole were assigned. The resonance Raman spectra of imidazole and 4‐formaldehyde imidazole were obtained in methanol and acetonitrile with excitation wavelengths in resonance with the first intense absorption band to probe the short‐time structural dynamics. complete active space self‐consistent field calculations were carried out to determine the minimal singlet excitation energies and structures of S1(nπ*), S2(ππ*), and conical intersection point S1(nπ*)/S2(ππ*). The results show that the A‐band structural dynamics of imidazole is predominantly along the N1H/C4H/C5H/C2H in‐plane bending reaction coordinate, which suggests that excited state proton or hydrogen transfer reaction takes place somewhere nearby the Franck–Condon region. The significant difference in the short‐time structural dynamics between 4‐formaldehyde imidazole and imidazole is observed, and the underlying mechanism is interpreted in term of excited state charge redistribution. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
11.
M. Dehestani 《Journal of Raman spectroscopy : JRS》2009,40(6):696-702
The time‐correlation function formalism has been used to calculate resonance Raman cross sections, excitation profiles, and electronic absorption spectra of the OClO molecule in the gas‐phase and in different solvents like cyclohexane, chloroform, and water. The multidimensional time domain integrals that arise in these calculations have been evaluated for the case in which an X2B1 Ã2A1 electronic transition takes place between displaced‐distorted‐rotated harmonic potential energy surfaces. Ab initio calculations have been performed to provide the spectroscopic constants required for the evaluation of these integrals. The calculated absorption spectra and resonance Raman cross sections have been compared with the experimental results. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
12.
Rmulo A. Ando Rodrigo L. O. R. Cunha Luiz Juliano Antonio C. Borin Paulo S. Santos 《Journal of Raman spectroscopy : JRS》2008,39(4):453-459
The electronic (UV‐vis) and resonance Raman (RR) spectra of a series of para‐substituted trans‐β‐nitrostyrenes were investigated to determine the influence of the electron donating properties of the substituent (X = H, NO2, COOH, Cl, OCH3, OH, N(CH3)2, and O−) on the extent of the charge transfer to the electron‐withdrawing NO2 group directly linked to the ethylenic (C = C) unit. The Raman spectra and quantum chemical calculations show clearly the correlation of the electron donating power of the X group with the wavenumbers of the νs(NO2) and ν (C = C)sty normal modes. In conditions of resonance with the lowest excited electronic state, one observes for X = OH and N(CH3)2 that the symmetric stretching of the NO2, νs(NO2), is the most substantially enhanced mode, whereas for X = O−, the chromophore is extended over the whole molecule, with substantial enhancement of several carbon backbone modes. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
13.
Yi Yang Sheng Pan Jia‐Dan Xue Xuming Zheng Wei‐Hai Fang David Lee Phillips 《Journal of Raman spectroscopy : JRS》2014,45(1):105-113
The excited state structural dynamics of 4‐cyanobenzaldehyde (p‐CNB) were studied by using the resonance Raman spectroscopy and the quantum mechanical calculations. The experimental A‐ and B‐band absorptions were, respectively, assigned to the major nO → π3* and π2 → π3* transitions according to the B3LYP‐TD/6‐31G(d) and CIS/6‐31G(d) computations, and the resonance Raman spectra. It was determined that the actual S2(π2π3) state was in energy lower than S3(π1π3), which was just opposite to the B3LYP‐TD/6‐31G(d) calculated order of the S2(π1π3) and S3(π2π3). The vibrational assignments were carried out for the A‐ and B‐band resonance Raman spectra. The B‐band resonance Raman intensities of p‐CNB were dominated by the C2–C3/C5–C6 symmetric stretch mode ν8, the overtones nν8 and their combination bands with the ring C–H bend mode ν17, the C9–N10 stretch mode ν6, the C7–O8 stretch mode ν7 and the remaining modes. The conical intersection between S1(nOπ3) and S2(π2π3) states of p‐CNB was determined at complete active space self‐consistent field (CASSCF)(8,7)/6‐311G(d,p) level of theory. The B‐band short‐time structural dynamics and the corresponding decay dynamics of p‐CNB were obtained by analysis of the resonance Raman intensity pattern and CASSCF computations. The resonance Raman spectra indicated that CI[S1(nOπ3)/S2(π1π2π3π4)] located nearby the Franck–Condon region. The excited state decay dynamics evolving from the S2, FC(π2π3) to the S1(nOπ3) state was proposed. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
14.
Excited‐state hydrogen bond strengthening of coumarin 153 in ethanol solvent: a TDDFT study 下载免费PDF全文
Jinmei Xu Junsheng Chen Shunle Dong Aiping Fu Hongliang Li Tianshu Chu 《Journal of Physical Organic Chemistry》2016,29(6):305-311
So far, coumarin dyes have been extensively studied with various means to understand their photophysical behaviors and photochemical properties. Here, our performing time‐dependent density functional theory calculation is aimed at exploring the excited‐state hydrogen bonding dynamics of coumarin 153 (C153) in protic ethanol (EtOH) solvent. The calculated results suggest that the excited‐state hydrogen bond C?O?H?O between C?O group and O?H group in the C153‐EtOH complex is strengthened, and the S0 → S1 transition of the complex corresponds to the highest occupied molecular orbital (HOMO) hopping to the lowest unoccupied molecular orbital (LUMO). The excited‐state hydrogen bond strengthening has been further confirmed by its larger binding energy in the S1 state than in the S0 state. In addition, because of the formation of the hydrogen bond C?O?H?O, a red shift of about 7 nm occurs in the electronic spectra of the C153‐EtOH complex, which is in good accordance with the experiment result. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
15.
Andrew P. Mendham Rex A. Palmer Brian S. Potter Trevor J. Dines Martin J. Snowden Robert Withnall Babur Z. Chowdhry 《Journal of Raman spectroscopy : JRS》2010,41(3):288-302
Cyclo(L ‐Glu‐L ‐Glu) has been crystallised in two different polymorphic forms. Both polymorphs are monoclinic, but form 1 is in space group P21 and form 2 is in space group C2. Raman scattering and FT‐IR spectroscopic studies have been conducted for the N,O‐protonated and deuterated derivatives. Raman spectra of orientated single crystals, solid‐state and aqueous solution samples have also been recorded. The different hydrogen‐bonding patterns for the two polymorphs have the greatest effect on vibrational modes with N H and CO stretching character. DFT (B3‐LYP/cc‐pVDZ) calculations of the isolated cyclo(L ‐Glu‐L ‐Glu) molecule predict that the minimum energy structure, assuming C2 symmetry, has a boat conformation for the diketopiperazine ring with the two L ‐Glu side chains being folded above the ring. The calculated geometry is in good agreement with the X‐ray crystallographic structures for both polymorphs. Normal coordinate analysis has facilitated the band assignments for the experimental vibrational spectra. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
16.
Christian Merten Honggang Li Xuefang Lu Andreas Hartwig Laurence A. Nafie 《Journal of Raman spectroscopy : JRS》2010,41(12):1563-1565
Natural resonance electronic Raman optical activity (ROA) is observed for the first time. Coincidently, the first example of vibrational ROA enhanced by low‐lying electronic transition is reported. These new phenomena were measured using the rare‐earth complex Eu(tfc)3 (+)‐tris[3‐trifluoroacetyl‐D ‐camphorato]europium(III), where electronic resonance occurs between the 532‐nm laser excitation and the 7F1 → 5D1 transition of the Eu3+ metal center. Electronic Raman spectra involve the Raman transitions terminating on the low‐lying electronic states of Eu(tfc)3. The observed vibrational ROA spectra are enhanced relative to typical ROA spectra by the proximity of vibrational states of Eu(tfc)3 to its low‐lying electronic states with significant magnetic‐dipole character, whereas the parent vibrational Raman spectra do not appear to be resonance‐enhanced since the 532‐nm vibrational Raman spectrum has similar relative intensities to the corresponding Raman spectrum measured with 1064‐nm laser excitation. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
17.
Joseph Grondin Jean‐Claude Lassgues Dominique Cavagnat Thierry Buffeteau Patrik Johansson Roman Holomb 《Journal of Raman spectroscopy : JRS》2011,42(4):733-743
Imidazolium‐based ionic liquids (ILs) involving anions of variable coordinating strength have been investigated using infrared (IR) and Raman spectroscopies, density functional theory (DFT) calculations and selective deuteration of the imidazolium CH groups. Particular emphasis has been placed on the vibrational assignments of the anion and cation internal vibrations, a prerequisite before any interpretation of spectral changes due to ion–ion interactions in these unconventional liquids. The vibrations of highly symmetric and weakly coordinating anions, such as PF6−, have unperturbed wavenumbers, but unexpected IR or Raman activity for some modes, showing that the anion is subjected to an anisotropic electric field. The stretching as well as the in‐plane and out‐of‐plane bending modes of the imidazolium CH groups are anharmonic. They give broad bands that reflect a large distribution of interactions with the surrounding anions. All the bending modes are mixed with ring vibrations and the stretching modes are complicated by Fermi resonance interactions with overtones and combination of in‐plane ring modes. However, the stretching vibration of the quasi‐diatomic C(2) D bond appears to be a good spectroscopic probe of the increasing cation–anion interactions when the coordinating strength of the anion increases. The broad absorption observed in the far IR with weakly coordinating anions remains practically unchanged when the acidic C(2) H imidazolium bond is methylated and even when the imidazolium cation is substituted by tetra‐alkyl ammonium or pyrrolidinium cations. It is concluded that this absorption is a general feature of any IL, coming from the relative translational and librational motions of the ions without needing to invoke C(2) H anion hydrogen bonds. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
18.
Substituent effect on structure,stability, and aromaticity of novel BnNmC20–(n+m) heterofullerenes 下载免费PDF全文
Maryam Koohi Somayeh Soleimani Amiri Bibi Narjes Haerizade 《Journal of Physical Organic Chemistry》2017,30(11)
We are focusing our calculations on the structural stabilities and electronic properties of 26 novel BnNmC20–(n+m) heterofullerenes, with n, m = 1 ? 5, at B3LYP/6‐311++G** and B3LYP/AUG‐cc‐pVTZ levels of theory. Vibrational frequency calculations on C20 and its analogues show that except B2N2C16 (1) and B2N2C16 (2), all other heterofullerenes are true minima. The heats of atomization energies, binding energy, band gaps (ΔEHOMO‐LUMO), aromaticity, nucleus‐independent chemical shifts, thermodynamic stability, kinetic stability against electronic excitation, binding energy as a stability criterion of different configurations, geometrical parameters, conformational structures, conductivity, charge transfer, and possibility for hydrogen storage of these heterofullerenes strongly depend on their number of heteroatoms, topology, filling patterns, and locations as well as “B‐site and N‐site attachments.” B5N5C10 contains 5 alternating boron and nitrogen atoms in the equatorial position. It is predicted to be thermodynamically and kinetically the most stable against electron excites. Thus, it is energetically favorable and its electronic properties as well as stabilities make it perhaps a good candidate for an experimental investigation and testing verification. 相似文献
19.
Ming‐Xia Liu Bin‐Bin Xie Ming‐Juan Li Yan‐Ying Zhao Ke‐Mei Pei Hui‐Gang Wang Xuming Zheng 《Journal of Raman spectroscopy : JRS》2013,44(3):440-446
The structural dynamics of thioanisole in the S2(ππ*) electronic state that has large oscillator strength was studied by using the resonance Raman spectroscopy. The vibrational assignments were done for thioanisole on the basis of the FT‐Raman and FT‐IR measurements, the density‐functional theory computations and the normal mode analysis. The A‐ and B‐band resonance Raman spectra were obtained in cyclohexane, methanol and acetonitrile, in which ten modes in A’ irreducible representations were observed. The structural dynamics were obtained according to the resonance Raman intensity pattern. The vibroinc‐coupling between the S3(πσ*) electronic state that has no oscillator strength and the S2(ππ*) electronic state were revealed. We discuss the correlation between our present structural dynamics and the previous S2(ππ*)/S3(πσ*) conical intersectional dynamics revealed by resonant‐enhanced two‐photon ionization and the photofragment excitation spectroscopic study. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
20.
Huigang Wang Bo Liu Yanying Zhao Xuming Zheng 《Journal of Raman spectroscopy : JRS》2009,40(9):1312-1318
A‐ and B‐band resonance Raman spectra were acquired for ethylene trithiocarbonate in cyclohexane solution. The results indicate that the S3 state structural dynamics is mostly along vibrational motions of the CS stretch υ11, while the S4 state one has motions mainly via the S C S symmetric stretch υ18, CS stretch υ11, and the H C H rock + S C S antisymmetric stretch υ14 reaction coordinates. The very different excited state structural dynamics were briefly discussed in terms of vibronic couplings using local symmetry point group. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献