共查询到20条相似文献,搜索用时 15 毫秒
1.
Various approximations of the method of determining two-well potential functions of molecular inversion from experimental
data (geometrical parameters and inversion level energies) are considered. The potential of the method is illustrated by reference
to carbonyl molecules in the lowest excited states. Some of the current problems are discussed.
Translated fromZhurnal Strukturnoi Khimii, Vol. 39, No. 5, pp. 947–961, September–October, 1998 相似文献
2.
The vibrational structure of the electron transition to the second singlet excited state of pyridine N-oxide has been studied.
The frequency of the 0–0 transition is 34502 cm−1. A computer-aided technique for the assignment of the frequencies of the normal vibrations of polyatomic molecules in the
excited electronic states is proposed. The frequencies of the totally symmetric vibrations of pyridine N-oxide in the second
singlet electronically excited state are assigned.
N. G. Chernyshevskii Saratov State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 2, pp. 350–355, March–April, 1995.
Translated by I. Izvekova 相似文献
3.
The geometrical structure, force fields, and parameters of vibrational-rotational interaction of six-membered azacyclic compounds
in the ground and excited states are estimated using the structural dynamic model of a polyatomic molecule.
Translated fromZhurnal Struktumoi Khimii, Vol. 38, No. 2, pp. 345–349, March–April, 1997. 相似文献
4.
The structures of the perylene molecule in the first excited 11 0B2u state and the band shape (vibrational structure) of its fluorescence and absorption spectra are computed by the parametric
method. A fragmentary approach and the molecular fragments H/1C= with the parameters obtained for acenes and polyenes are
used to form molecular models in the excited state. It is shown that a model that corresponds to the choice of fragments with
the parameters of acenes is the most optimal. The theoretical spectra satisfactorily reproduce both qualitatively and quantitatively,
the basic specific features of the vibrational structure of the experimental spectra. Calculation results show high degree
of transfer of the parameters of the method in a series of related molecules not only for acenes with “linear” arrangement
of the rings (benzene, naphthalene, anthracene, etc.) but also for more complex structures (perylene). It is shown that the
parametric method developed is efficient for predicting the vibronic spectra and the structure of the excited states of complex
molecules.
Translated fromZhurnal Struktumoi Khimii, Vol.40, No. 2, pp. 242–250, March–April, 1999. 相似文献
5.
V. I. Tyulin G. M. Kuramshina Yu. A. Pentin Le Hyu Ho 《Journal of Structural Chemistry》1997,38(2):231-235
The direct and inverse vibrational problems are solved for the rotational isomers of the glyoxal and oxalyl halide molecules
in the ground and first excited singlet states.
Translated from Zhurnal Strukturnoi Khimii, Vol. 38, No. 2, pp. 287–292, March–April, 1997. 相似文献
6.
Yu. I. Naberukhin V. A. Luchnikov G. G. Malenkov E. A. Zheligovskaya 《Journal of Structural Chemistry》1997,38(4):593-600
The local structure of the molecular- dynamic model of water (729 particles at 300 K) is analyzed by isolating molecules whose
surroundings differ slightly in configuration from a regular tetrahedron. These molecules are not randomly distributed in
space but form nanometer clusters having a fractal structure. In these clusters, molecules are less mobile than the model
molecules in general;their self- correlation function of rate and the density of vibrational states also differ from the average characteristics of
the system.
Translated fromZhumal Strukturnoi Khimii, Vol. 38, No. 4, pp. 713–722, July–August, 1997. 相似文献
7.
The results of the analysis of the fluorescence excitation spectrum of trans-hexafluorobiacetyl published earlier are revised.
New values of torsion frequencies and potential barriers of internal rotation of the CF3 group in the ground and excited states of the molecule are obtained. A procedure for calculating the probabilities of torsional
vibronic transitions of molecules is described.
Translated fromZhurnal Struktumoi Khirnii, Vol. 38, No. 2, pp. 293–302, March–April, 1997. 相似文献
8.
N. M. Pozdeev A. Kh. Mamleev L. N. Gunderova R. V. Galeev G. R. Garipova V. I. Tyulin 《Journal of Structural Chemistry》1995,36(3):380-385
The microwave spectra of s-cis-glyoxal molecules in the excited states of torsional (vt=1,2) and bending (vbend=1) vibrations have been studied. For the vt=1 state, the rotational constants have been refined and the quartic constants of centrifugal distorition have been determined.
For the excited vt=2 and vbend=1 states, the rotational constants have found. For the ground vibrational state, the rotational constants and the quartic
constants of centrifugal distortion have been refined. The vibrational frequencies have been determined from the relative
intensities of rotational transitions.
Ufa Scientific Center of Russian Academy of Sciences, Physics Department. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 3, pp.418–423, May–June, 1995.
Translated by I. Izvekova 相似文献
9.
E. A. Gastilovich N. V. Korolkova V. G. Klimenko 《Journal of Structural Chemistry》2000,41(1):123-128
A simple procedure is suggested for estimating changes in the bond lengths q and angles a between them in the excited ππ states
of molecules avoiding calculations of molecular vibrations. The distances q and the angles a are estimated for the triplet
state B1u (ππ*) of the tetm-β-chlomdioxin molecule.
Translated from Zhumal Struktumoi Khimii, Vol. 41, No. 1, pp. 149-156, January–February, 2000. 相似文献
10.
G. N. Ten V. V. Nechaev V. I. Berezin V. I. Baranov 《Journal of Structural Chemistry》1997,38(2):268-276
The vibrational structure of the absorption spectra of the first two π-π* singlet transitions of adenine is calculated in
the Franck-Condon approximation including Herzberg-Teller interactions. The effect of excitation-induced changes in molecular
angles on the intensities of the vibrational components is estimated. Structural models of the adenine molecule in the excited
states are constructed. The theoretical and absorption spectra of the first π-π* transition are compared. The results of the
electronic structure calculations of adenine by different CNDO/S methods are discussed.
Translated fromZhumal Struktumoi Khimii, Vol. 38, No. 2, pp. 334–344, March–April, 1997. 相似文献
11.
V. A. Benderskii 《Russian Chemical Bulletin》1999,48(12):2187-2199
12.
The 9,10–1,10-anthraquinoid tautomer was found to be characteristic of physcion and emodin and their analogs in solutions
using spectrophotometric, quantum-chemical, and correlation methods. Ionization of these compounds was accompanied by a shift
in tautomeric equilibrium. In alkaline solutions 1,10-anthraquinoid anions with a single α-hydroxy that were stabilized by
an intramolecular H-bond were formed. Tautomerism occurred in both the ground and excited states of the molecules.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 411–415, September–October, 2005. 相似文献
13.
This paper deals with the mechanisms of localization of Franck-Condon vibronic coupling of πσ*- or πlπ*-orbital type in a few vibrational modes, (LVM) in excited electronic states of polyatomic molecules. The analysis of vibronic
coupling uses highly symmetric basis sets (for representing MO structures and normal coordinates ξR) as well as simplified models that relate the shift ΔR of the electron potential minima along the normal coordinates to the MO structure and to ξR in the form of analytical expressions. The modes that are active in LVM are determined from the experimental luminescence
spectra. These ideas about approximately high local symmetry of vibronic coupling in benzene fragments as well as the estimates
of ΔR depending on variations in the MO structure explain the experimental results.
L. Ya. Karpov Physicochemical Scientific Research Institute. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 2, pp. 286–291, March–April, 1995.
Translated by L. Smolina 相似文献
14.
Tunnel states of dimeric mixed-valence clusters with dn-dn+2 type two-electron transfer are considered. General expressions for the matrix elements of the double exchange operator are
obtained taking into account the contributions of the excited states. The energy spectrum of the clusters is calculated and
the magnetic properties are studied. Allowance for the dn+1-dn+1 excited states considerably affects the energy spectrum and the magnetic properties of the systems.
Translated fromZhurnal Strukturnoi Khimii, Vol. 38, No. 6, pp. 1038–1045, November–December, 1997. 相似文献
15.
V. G. Yarzhemsky 《Journal of Structural Chemistry》1998,39(6):805-810
A theory of lineshape in photoelectron spectra is developed based on the Green’s function calculation of the atomic vacancy
structure. It is shown that the broadening of photoelectron lines is always somewhat asymmetrical, and the broadening of satellite
lines arising in atomic photoionization is generally strongly asymmetrical and inverse. The approach is generalized to low-energy
Auger spectra; it is shown that Auger decay lines of excited atomic states may narrow with respect to the width of the initial
level. The results are compared with experimental photoelectron spectra.
Translated fromZhurnal Strukturnoi Khimii, Vol. 39, No. 6, pp. 985–991, November–December, 1998. 相似文献
16.
The absorption spectra of decapentaene are analyzed and calculated using the available efficient methods of calculating the
matric elements of the vibronic problem, a new parametric method for determining the potential surfaces of excited molecules,
and a fragmentation approach to the design of molecular models. Good agreement for the fine vibrational structure of the calculated
and experimental spectra (differences between the main band frequencies and intensities less than 20 cm−1 and 10%, respectively) is obtained without correcting the parameters of the method. The mechanisms of excitation-induced
structural changes in linear polyenes and the effect of bond angle changes on the vibrational structure of the spectrum are
revealed. A new interpretation of the absorption spectrum of decapentaene in an argon matrix is proposed [J. Mol. Spectrosc.,114, 54–59 (1985)]. It is shown that the parametric method allows quantitative prediction of fine structure for the vibronic
spectra of complex molecules.
K. A. Timiryazev Moscow Agricultural Academy. Translated fromZhurnal Strukturmoi Khimii, Vol. 37, No. 6, pp. 1031–1039, November–December, 1996.
Translated by I. Izvekova 相似文献
17.
T. G. Burova 《Journal of Structural Chemistry》1997,38(2):201-206
A direct method for calculating the resonance Raman and two-photon absorption spectra of polyatomic molecules is described
in detail The method is based on the adiabatic model and uses Herzberg-Teller’s approximation. Relations ruling out direct
summation over vibrational quantum numbers of excited electronic states and representing the matrix elements of the Green
function of a multidimensional oscillator as functions of vibration frequencies and Dushinsky transformation parameters are
derived. The relations are convenient for constructing algorithms.
Translated from Zhumal Struktumoi Khimii, Vol. 38, No. 2, pp. 248–255, March–April, 1997. 相似文献
18.
The parameters of the adiabatic model of the stilbene molecule in the excited state and the vibrational structure of the fluorescence
spectrum are calculated by the parametric method of the theory of vibronic spectra of complex molecules. The first and second
orders of theory are used. The molecular models are constructed by the fragment method. Satisfactory agreement with experiment
is obtained. The parameters of molecular fragments are shown to be highly transferable. The model and the spectrum max be
refined in the second order of theory using only one additional parameter for CCC angles (optimal values were obtained). The
parametric method under discussion makes it possible to predict variations of structural parameters due to excitation and
to calculate the vibrational structure of the electronic spectra of complex molecules, including characteristic variations
of the spectra in series of related molecules (stilbene-di-phenylpolyenes). This method surpasses all previous procedures
(in particular, the correlation method) in completeness and accuracy of results.
Translated fromZhurnal Strukturnoi Khinii, Vol. 41, No. 2, pp. 369–378, March–April, 2000. 相似文献
19.
N. N. Yakovlev A. V. Abramenkov I. S. Belozerskii S. B. Sverchinskaya I. A. Godunov 《Journal of Structural Chemistry》1995,36(2):281-286
The potential functions of inversion in the S1 states are determined from the inversion transitions (out-of-plane C=O vibrations) found in the S1←S0 vibronic spectra of acetyl halide molecules. The high intensities of the hot inversion transitions are explained by the high
probabilities of these transitions. The literature values of the inversion potentials (equilibrium values of angles formed
by the C=O bonds deviating from the planes) of formyl halide molecules in the S1 states are refined. The inversion potentials of formyl and acetyl halides are similar.
M. V. Lomonosov Moscow State University, Chemical Faculty. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 2, pp. 316–321, March–April, 1995.
Translated by L. Smolina 相似文献
20.
Novel approximate methods for calculating the vibrational structure of the electronic spectra of polyatomic molecules—a method
for the direct calculation of the overlap integrals of vibrational wave functions for the electronic states involved in a
transition and a variational method for the solution of the vibrational problem for the excited states—are discussed. The
methods are based on the consideration of the displacement and entanglement of normal coordinates, the quasiorthogonality
of the Dushinsky transformation, and the classification of the states by total vibrational quantum numbers. Matrix perturbation
theory is employed. It is shown that the accuracy of these methods compares well with the accuracy of the available “exact”
techniques (the errors are ∼1 cm−1 for frequency and 10% for relative intensity). At the same time, calculations by the new methods are performed more than
two orders of magnitude faster than by the previously known methods.
K. A. Timiryazev Agricultural Academy, Moscow. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 2, pp. 217–230, March–April, 1995.
Translated by I. Izvekova 相似文献