Vibrational structure of quasiline fluorescence and absorption spectra of bisanthene molecules

The quasiline spectra of the fluorescence and absorption of bisanthene in n-hexane are obtained at 77 and 4.2 K, and their vibration analysis is carried out. Substantial violation of the mirror symmetry of the fluorescence and S₁ ← S₀-absorption bands with respect to both the frequencies and intensities is found. This allowed the conclusion that the S₂-level is localized in the region of vibronic sublevels of the S₁-state with . Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 4, pp. 488–491, July–August, 2000.     

Quasiline fluorescence and absorption spectra of NH-isomers of octamethylisobacteriochlorin

Quasiline fluoresence and fluorescence excitation spectra of NH-isomers of 2,2,7,7,12,13,17,18-octamethylisobacteriochlorin (cis- and trans-) in polycrystalline matrices in n-hexane and n-octane at 4.2 K are obtained. A vibration analysis of the spectra in combination with the data of quasiline spectra of cyano-substituted octaethylisobacteriochlorin and octamethylporphin permitted a qualitative interpretation of the vibronic spectra of NH-isomers. It is inferred that for a trans-isomer, the 0–0 transition S₂⇃S₀ is localized in the region of electron-vibrational S₁⇃S₀ transitions; the interval S₂-S₁ has a magnitude of about 1300 cm⁻¹. Reported at the VIIIth International Conference on the Spectroscopy and Chemsitry of Poprhyrins and Their Analogs, Belarus, Minsk, September 22–26, 1998. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 1, pp. 79–85, January–February, 2000.     

Absorption,fluorescence, and SERS spectra of sanguinarine at different pH values

We have studied the absorption, fluorescence, and surface-enhanced Raman scattering (SERS) spectra of sanguinarine using a silver hydrosol and an electrochemical cell with a silver working electrode for different pH values in the medium. We carried out quantum chemical calculations in order to interpret the electronic and vibrational spectra and to establish their correlations with the structure of the molecules. We optimized the structure and determined the spectral characteristics of the cationic and neutral forms of the sanguinarine molecules in solution and adsorbed on the surface of an anodized Ag electrode for different potentials. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 5, pp. 604–609, September–October, 2007.     

Absorption and fluorescence spectra of hybrid silicon-organic materials in solutions and films

The spectroscopic characteristics of hybrid organic-inorganic films and solutions of ethoxysilicon-containing amidophosphate ligands in acetonitrile have been investigated. Inhomogeneous broadening of the absorption and fluorescence spectra which is characterized by the spectral dependence of the fluorescence and fluorescence excitation bands on the excitation and registration wavelength, respectively, is associated with the presence of a set of -(Si-O)_n- siloxane structures with various terminal fragments in both the films and solutions. The established general spectral rules are discussed with allowance for the characteristic features of the electronic structure of silicon-organic compounds containing an oxygen atom the unshared electron pair of which ensures the delocalization of the electron density over the siloxane chain.Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 71, No. 6, pp. 788–792, November–December, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Dependence of the spectroscopic properties of pentauranylfluoride crystals on temperature in the range from 4.2 to 40 K

Using the configuration interaction model, we investigate the dependence of the shape, half-width, and position of the phononless lines (PL) in absorption and luminescence spectra of K₃UO₂F₅ and Rb₃UO₂F₅ crystals in the region 4.2–40 K. It is established that a Stokes shift in combining electron states leads to a nonsymmetric distortion in the Gauss shape of thePL. The temperature broadening of the PL is mainly associated with a change in the population of the initial states of oscillators (of the ground state for absorption and the 1 st excited state for luminescence), while a shift in maxima of the PL is caused by the forbidden 1 st electron transitions in complex uranyl compounds and is determined by the nonlinear electron-phonon interaction. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 6, pp. 824–827, November–December, 1999.     

Electronic spectra of cationic forms of meso-tetrapropylporphin in a nanoporous silicate gel matrix

We have studied the fluorescence and fluorescence excitation spectra at 300 K, 77 K, and 4.2 K for silicate gel matrices colored with meso-tetrapropylporphin by impregnation of the matrix with a solution of the pigment. Comparison of the data obtained with the absorption spectra in acidified solutions and analysis of the low-temperature fine-structure vibronic spectra, and also taking into account data obtained earlier for octaethylporphin in a xerogel showed formation of two cationic forms of meso-tetrapropylporphin in the gel matrix: the short-wavelength form has a dicationic structure, while the long-wavelength form has a monocationic structure. We have traced out the correlations of the vibrational structure in the spectra of the dicationic form with data for the porphin dication, and we have drawn a number of conclusions concerning the normal vibrational modes that are active in the vibronic fluorescence and absorption spectra of the studied cationic forms. Using the AM1 semiempirical quantum chemical method, we optimized the geometry of the mesotetrapropylporphin dication: the most stable of the possible conformers is the dication structure with saddleshaped macrocycle nonplanarity. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 4, pp. 453–461, July–August, 2006.     

IR absorption and surface-enhanced Raman spectra of the isoquinoline alkaloid berberine

We present the IR absorption and surface-enhanced Raman scattering (SERS) spectra of the isoquinoline alkaloid berberine adsorbed on a silver hydrosol and on the surface of a silver electrode for different potentials. Based on quantum chemical calculations, for the first time we have assigned the vibrations in the berberine molecule according to vibrational mode. The effect of the potential of the silver electrode on the geometry of sorption of the molecule on the surface is considered, assuming a short-range mechanism for enhancement of Raman scattering. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 1, pp. 31–36, January–February, 2007.     

Steady-state analysis of three-photon absorption spectra via density-matrix method in a three-coupled-quantum-well nanostructure

We numerically simulate three-photon absorption spectra in a three-coupled-quantum-well nanostructure interacting with a pump field,a coherent coupling field,and a probe field.We find that the three-photon absorption spectra can be dramatically influenced due to the intensities of the coupling field and pump field changing under the three-photon resonance condition.The effect of the frequency detuning of the pump field on the three-photon absorption spectra is also discussed.The study in our case is much more practical than the study in the case of its atomic counterpart in the sense of flexible design and the wide adjustable parameters.Thus it may open up some new possibilities for technological applications in optoelectronics and solid-state quantum information science.     

Temperature dependence of the fine structure of vibronic bands of fluorescence of 1,4,5,8-tetraoxy-9,10-anthraquinone in a polymer matrix

L. Ya. Karpov Physicochemical Research Institute, 10, Obukhov Str., Moscow, 103064, Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 2, pp. 65–69, March–April, 1995.     

Method for assigning absorption bands in IR spectra of polyatomic molecules with respect to internal vibrational coordinates

A method is proposed for assigning absorption bands in IR spectra of polyatomic molecules. An algorithm is developed and a Fortran program is written based on this method. The method is illustrated for the example of the toluene molecule. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 2, pp. 169–173, March–April, 2007.     

X-ray dichroism in biaxial gyrotropic media: Differential absorption and fluorescence excitation spectra

The differential absorption and the differential change in the polarization state of an X-ray beam propagating inside a gyrotropic crystal are described using a Müller matrix, the 16 elements of which are related to the anisotropic components of the multipolar polarizability tensors at the absorbing site. Analytical expressions are given up to third order for X-ray linear and circular dichroism, X-ray optical rotation and X-ray circular polarimetry in transmission. The same formalism is extended to discuss Fluorescence detected dichroism spectra with or without polarization analysis of the fluorescence. Fluorescence detected dichroism is strictly proportional to dichroism measured in the transmission geometry only for uniaxial crystals. In biaxial crystals, the tiny effects of X-ray gyrotropy are swamped by large linear dichroism signals due to the imperfect polarization transfer function of Bragg monochromators. Second order effects should also be taken into consideration. Our general formulation of linear and circular dichroism includes terms of odd parity with respect to the action of the time reversal operator: such terms cannot contribute to natural dichroism but can be activated by a magnetic field. The terms responsible for X-ray magnetic circular dichroism are well known but non-reciprocal X-ray gyrotropy effects are also predicted in magnetic crystals of appropriate symmetry. Received 3 March 1999     

低对称畸变晶场下YIG和YGG:Fe~(3+)吸收光谱的理论解释

本文利用络合物中Fe~(3+)的SCF-d轨道理论,分别在实际的低对称场D_(3d)和S_4下对YIG和YGG:Fe~(3+)中的d-d跃迁谱进行了理论计算。仅用两个参数和μ就解释了YIG中10800cm~(-1),21150cm~(-1),25700cm~(-1),27600cm~(-1)处的谱分裂,并且指出YGG:Fe~(3+)中的26320cm~(-1),26970cm~(-1)为Fe~(3+)对的双中心跃迁谱。基本澄清了YIG和YGG:Fe~(3+)吸收谱理论的某些混淆。     

Extra-liganding effects in Zn-octaethylporphyrin solutions in a temperature interval of 300-77 K

It is established experimentally for the first time that Zn-octaethylporphyrin in a solution of dried methyl cyclohexane is in unliganded form in the temperature interval of 293-77 K. This form is characterized by the shortest-wave position of absorption and luminescence spectra, the independence of the degrees of fluorescence and phosphorescence polarizations from the excitation wavelength, and high phosphorescence time (τ_T=126 μsec) and quantum yield (φp=0.085) at 77 K. Adding electrodonor components to the methyl cyclohexane or going over to alcohol-containing polar media leads to the formation of a monoliganded form of ZnOEP, for which we observe a bathochromic shift of ≈150–350 cm⁻¹ for Q(0,0) absorption and luminescence bands, a splitting of ≈50–100 cm⁻² for the Q(0, 0) absorption band, and phosphorescence quenching (τ_T=60 μsec, φp=0.05-0.03 at 77 K). The effects revealed are explained by a decrease in the symmetry of a ZnOEP molecule in extra liganding and by an increase in the probability of nonradiative activation for a T₁-state due to the extra ligand being involved in the exchange of electron-excitation energy and to the enhancement of a spin-orbital coupling as a result of the disturbance of the planarity, of a macrocycle. Institute of Molecular and Atomic Physics, National Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 6, pp. 900–907, November–December, 1998.     

Anharmonic resonances in the vibrational spectra of pyrazine

The quartic force field of pyrazine has been calculated in the B3LYP/6-31G(d) hybrid density-functional approximation. Based on the results of this calculation, the total IR (250–3800 cm^–1) and Raman (400–3200 cm^–1) spectra of pyrazine have been interpreted with consideration for the Fermi and Darling-Dennison resonances and their spectral manifestations. A precision method is proposed for anharmonic analysis of the vibrational states of polyatomic molecules on the basis of consideration of their theoretical anharmonicity constants in combination with the corresponding experimental frequencies. The method of linear scaling of frequencies has been theoretically substantiated.__________Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 1, pp. 13–22, January–February, 2005.     

Laser absorption and fluorescence diagnostics of a plasma

Diagnostics of a near-surface laser plasma, the plasma of a strong-current pulse gaseous discharge in inert gases, nitrogen, and carbon dioxide under conditions of intense evaporation of the wall of the discharge chamber, the plasma of a discharge with a hollow cathode, and the active medium of an excimer laser was conducted by methods of intracavity laser spectroscopy and laser-induced fluorescence. The dynamic fields and absolute concentrations of atoms, ions, molecules and electrons, the plasma temperature, and the velocities of flows of particles were measured. The quantitative determination of the density of particles in the erosion laser flame prior to breakdown and the phenomena associated with the formation of molecules in the laser plasma received primary consideration. To whom correspondence should be addressd. Instite of Molecular and Atomic Physics of the Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 3, pp. 281–290, May–June, 1997.     

Finite temperature vibronic spectra of harmonic surfaces: a time-dependent coupled cluster approach

An algorithm to compute vibronic spectra of harmonic surfaces including Dushinsky rotation and Hertzberg–Teller terms is described. The method, inspired by thermo field dynamics, maps the thermal density matrix onto the vacuum state and uses the time-dependent coupled cluster ansatz to propagate it in time. In the Franck–Condon approximation where the dipole matrix elements are taken to be constants, this reduces to the auto correlation function of the new vacuum. In the Hertzberg–Teller approximation, the full time evolution operator is needed. This too is governed by a closed set of equations. The theoretical development is presented along with an application to anthracene.     

The emission and absorption spectra of chromyl chloride in an argon matrix at 4 K

The emission and absorption spectra of chromyl chloride (and the pure ³⁵Cl isotopic species) have been obtained in an argon matrix at 4 K. In emission, two systems are obtained and these correlate with the two systems previously found in the absorption spectrum of the pure crystal and which were analyzed as the lowest singlet and triplet systems. The emission systems have, therefore, been assigned as phosphorescence and fluorescence.