Calculation of torsional and rotational raman spectra of hydrogen peroxide

We present calculated intensity distributions in torsional, rotational, and torsional-rotational Raman lines in spectra of hydrogen peroxide. Ab initio calculations of polarizability tensor components as functions of internal rotation angle were carried out in the HF/6-311G approximation. It is shown that the structure and transformational properties of the polarizability tensor components of hydrogen peroxide in extended molecular symmetry group G₄(EM) permit formation of purely rotational and torsional and rotational-torsional Raman spectra. Common expressions to calculate Raman line intensities governed by torsional and rotational motions of the non-rigid symmetric top molecule are obtained. The torsional components of the line intensities have been calculated by estimating the appropriate matrix elements. The contribution of rotational components has been calculated using the 3j-symbols technique.     

Torsional, rotational, and torsional-rotational energy levels of arbitrary molecules with a single internal rotation axis

A program is developed to calculate the torsional-rotational energy levels of multi-atomic molecules containing symmetric or antisymmetric frame and rotor. The torsional-rotational, rotational, and torsional energy levels of the molecules H₂O₂ (asymmetric rotor), C₂H₆ (symmetric rotor), and CH₃NH₂ (asymmetric rotor) are calculated. The value obtained are compared with the corresponding systems of energy levels found by other authors. Ivanovo State Textile Academy, Ivanovo. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 42, No. I, pp. 71–80. January, 1999.     

Enhancement of Europium Luminescence in Tetracycline–Europium Complexes in the Presence of Urea Hydrogen Peroxide

An increase in the europium emission band was observed, for the first time, with addition of urea hydrogen peroxide to the tetracycline–europium (Tc–Eu)solution. We have observed that the wavelength, the band width and the area of ⁵D₀→⁷F₂ europium transition change with the urea hydrogen peroxide concentration. We claim that the tetracycline–europium complexes can be used as probes of urea hydrogen peroxide concentration.     

Fluorescence excitation spectra of jet-cooled carbazole complexes with monohydric alcohols

We have analyzed the fluorescence excitation spectra of carbazole complexes with a single molecule of methyl, deuterated methyl, ethyl, and propyl (1-propanol and 2-propanol) alcohols, cooled in a supersonic jet. We have determined the shifts in the fluorescence excitation spectra of the complexes relative to the frequency of the purely electronic transition of unbound carbazole. They occur as a result of formation of hydrogen bonds between the N-H group of the carbazole and the OH group of the alcohols. The frequencies of stretching vibrations of the hydrogen bonds with different alcohols vary within the range 150–157 cm⁻¹, while the frequencies of the bending vibrations vary in the range 21–22.9 cm⁻¹. From the shape of the rotational contours of the bands for the purely electronic and vibronic transitions of the complexes, we determined that they belonged to rotational conformers. We calculated the equilibrium configurations of the complexes in the ground state. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 6, pp. 756–760, November–December, 2007.     

Comparison of the dynamics of MIL-53(Cr) and MIL-47(V) frameworks using neutron scattering and DFT methods

The low-frequency modes of MIL-47(V) and MIL-53(Cr) frameworks have been measured by inelastic neutron scattering. The librational modes of benzene are very close in frequency in the two structures. First-principles calculations have been performed to assign the measured spectra. The calculated values of the rotational barriers of the benzene rings are in reasonable agreement with experimental data. The relatively large barriers (413–588 meV) explain the absence of quasi-elastic broadening on the neutron time scale.     

Spectral luminescence properties of Eu(III) complexes with tetracycline antibiotics and hydrogen peroxide

We have studied the spectral luminescence properties of mixed-ligand complexes of Eu(III) ions with tetracyclines and hydrogen peroxide. We have established that incorporation of hydrogen peroxide into the inner sphere of these complexes leads to a significant increase (by a factor of 10–25) in the intensity of luminescence of the Eu(III) ions, redistribution of the intensities of the ⁵D₀ → ⁷F_j transitions, in particular to an anomalous increase in the intensity of the band for the forbidden transition ⁵D₀ → ⁷F₀. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 3, pp. 310–314, May–June, 2007.     

Transformation of strong picosecond pulses in radiation with an extended quasirotational spectrum during self-focusing in high-pressure hydrogen

Radiation with a spectrum representing a discrete analog of the extended spectrum observed in the generation of a supercontinuum in gases is generated in the self-focusing of 30-ps pulses with a wavelength of 1.06 μ]m in hydrogen at pressures up to 120 atm. The spectrum contains lines with similar intensities, an average frequency spacing approximately equal to the rotational transition frequency in hydrogen (587 cm⁻¹), and a smooth spatial profile. The lines consist of several vibrational-rotational components. As the pressure is increased, the spectral lines are transformed so that at a pressure above 60 atm each line in the spectrum contains one or two components formed as a result of the smaller number of cascade (rotational and vibrational) processes. Self-focusing is manifested in the occurrence of a radiating channel up to 12 cm in length. The formation of a channel of this length is associated mainly with the variation of the refractive index in vibrational excitation of the hydrogen molecules by electrons heated in the pump field. Zh. éksp. Teor. Fiz. 115, 479–493 (February 1999)     

Calculation of properties of the ozone molecule by the multiconfigurational self-consistent field method

For the ground state of the ozone molecule, by using the multiconfigurational self-consistent field method, we calculated the electric and magnetic properties — quadrupole moment, polarizability, tensor of magnetic susceptibility, nuclear quadrupole interaction constant, and the rotational g-factor. Qualitative agreement between the calculated parameters and experimental values was obtained. The tensors of chemical shielding in the spectrum of the nuclear magnetic resonance for the ¹⁷O isotopes have also been predicted (without allowance for the contribution made by the spin of the electrons). __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 6, pp. 713–716, November–December, 2005.     

The Antioxidative Activity of Riboflavin in the Presence of Antipyrin. Spectroscopic Studies

The effect of Antipyrin upon the antioxidant activity of the riboflavin has been evidenced using chemiluminescent system luminol–hydrogen peroxide, in Tris–HCl buffer, pH 8.5. It was found that riboflavin antioxidant activity depends on the reaction time and the Antipyrin concentration. Using ESR spectroscopy the hydroxyl radical generation, in the mentioned chemiluminescent system, was evidenced. The interaction between reactants was also investigated by UV-VIS and fluorescence spectroscopy. The effect of Antipyrin concentration upon the riboflavin fluorescence has also been investigated. The fluorescence quenching by Antipyrin is not significant and subsequently the riboflavin fluorescence quenching doesn’t indicate an electron transfer process through diffusion-controlled mechanism. The results are discussed with relevance to the redox processes of riboflavin.     

Calculation and analysis of vibrational spectra of adenine–thymine,guanine–cytosine,and adenine–uracil complementary pairs in the condensed state

We have calculated the frequencies of the normal vibrations of the complementary nucleic acid base pairs adenine–thymine, guanine–cytosine, adenine–uracil, corresponding to the Watson–Crick structure, and the adenine–uracil pair, corresponding to the Hoogsteen structure, in condensed states and we interpret the spectra. We determine the contributions of hydrogen bonds to the vibrational modes of the complementary pairs. We have analyzed the nature of the relative displacements of the nucleic acid bases as integral molecular units along the hydrogen bonds. We show the role of hydrogen bonds in tautomeric interconversions of complementary nucleic acid base pairs. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 1, pp. 84–92, January–February, 2009.     

Spectroscopic study of rotational energy distribution of BH (A 1Π) and electronic excitation temperature determination

Emission spectra of BH(A ¹Π-X ¹Σ⁺) system were recorded and studied using a low pressure (3.0 torr) arc in flowing hydrogen and argon + hydrogen mixture. The rotational distributions in theA ¹Π state determined from the intensities of rotational lines for the 0–0 band of theA-X system conforms to a Maxwellian distribution with effective rotational temperature of 1000 ± 50°K. Intensities of Balmer lines of hydrogen were measured and used to determine electronic excitation temperature which was found to be around 2000°K.     

Rotational Diffusion of Coumarins in Alcohols: A Dielectric Friction Study

The rotational dynamics of three structurally similar polar molecules viz., coumarin 440, coumarin 151 and coumarin 450 has been studied in alcohols at room temperature using steady-state fluorescence depolarization method and time correlated single photon counting technique. The observed reorientation times of all the three probes are found to be longer than those predicted by Stokes–Einstein–Debye (SED) hydrodynamic theory with stick boundary condition and a deviation towards super-stick behavior is noted. Dielectric friction theories of Nee–Zwanzig and van der Zwan–Hynes, which treat the solute as a point dipole, overestimate the dielectric friction contribution exhibited by all the three coumarins in alcohols. Results are discussed in the light of theoretical models and the possibility of hydrogen bonding between the amino group of the probe molecules and the hydroxyl group of the alcohols.     

Multilevel rotational transitions in the intermediate stage of three-photon ionization of molecules

Ionization and dissociation of diatomic molecules induced by a weak field (after preliminarily populating an intermediate level) and by intense, linearly polarized monochromatic radiation have been studied. Field-induced mixing of rotational components of various electronic-vibrational states of molecules (such as CO, NO, etc.) at field strength f∼10⁻⁴–10⁻⁵ atomic units can lead to migration among states with different angular momenta J. Therefore, ions with rotational momenta J ⁺ much higher than those prescribed by selection rules for three-photon absorption can be formed from molecules in the ground state. The possibility of selective formation of ions with J ⁺≫1 and zero projection of the angular momentum on the polarization vector of the external electromagnetic radiation has been investigated. Zh. éksp. Teor. Fiz. 111, 1624–1632 (May 1997)     

Phase Correlations and Polarization Characteristics of Dye-Solution Laser Radiation

The influence of phase correlations of components on the energy and polarization parameters of output radiation have been calculated within the framework of the formalism of polarization components. It is shown that these correlations have a marked effect only on the energy characteristics. At the same time, an analysis of the polarization characteristics of a probe wave provides rich information for the analysis of the phase-polarization structure of radiation. An analysis of experimental data allows the inference that the correlation of components is relatively weak even for lasers with a high-Q resonator and at a high excess of threshold values. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 5, pp. 591–597, September–October, 2005.     

Physical and electrochemical properties of vanadium alloy oxide layers prepared by anodic passivation

Thin oxide layers of high purity metals are suitable as redox electrodes in aqueous solutions. Concentrations of hydrogen peroxide could be analyzed potentiometrically. In dependence on the pH-value Nerstian behaviour was observed in the range of 0.1–30 g/l (H₂O₂) approximately. It is assumed that this electrochemical behaviour of the oxide layer is mainly influenced by electronic and ionic defects. Alloys of vanadium and titanium are included in the investigation. In order to clarify the mechanism in detail, electrochemical measurements (voltammetry, EIS) and surface analytical investigations (XRD, AES, XPS) have been carried out. Paper presented at the 7th Euroconference on Ionics, Calcatoggio, Corsica, France, Oct. 1–7, 2000.     

The torsion potential function of hydrogen peroxide and disulfan molecules

A method for constructing the torsion potential function of hydrogen peroxide and disulfan molecules which takes into account the magnitudes of intramolecular interactions is suggested. The new representation of the potential is used to calculate the torsion spectra of the molecules indicated. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 4, pp. 450–452, July–August, 2000.     

Photoinduced chirality of hydrogen peroxide molecules

The feasibility of using nonlinear optical techniques to control the chiral states of molecules is examined with the hydrogen peroxide molecule as an example. Raman excitation of optical activity owing to a transition among states with different chiral symmetries is proposed, along with an experimental scheme for detecting the corresponding photoinduced optical rotation in hydrogen peroxide vapor. Zh. éksp. Teor. Fiz. 116, 1250–1263 (October 1999)     

Molecular structure of trimethyl[(3-indole)ethoxy]silane cooled in a supersonic jet

Conformations of He-jet-cooled trimethyl[(3-indole)ethoxy]silane (TIES) have been studied using a laser spectroscopy technique in combination with quantum-chemical computations. Six probable conformers of the molecule were computed, of which only two conformations were observed. Based on an analysis of fluorescence excitation spectra, fluorescence spectra, shapes of rotational band contours at the electronic S₀–S₁ transition of TIES, and theoretical computations, the above conformers were assigned to steric structures. Twisted structures have the lowest energy due to intramolecular hydrogen bonds C - H ?O < _C^Si C - H \cdots O <_C^{Si} between hydrogen atoms of methyl groups and an oxygen atom and C–H···π between H and the π-electron cloud of the indole ring.     

Rotational dynamics in anisotropic confinement

Quasi-elastic nuclear resonant forward scattering experiments of the model glass former DBP:FC (Dibutylphthalate:Ferrocene) have been performed in anisotropic confinement, yielding complex spectra. A model for the rotational relaxation of Ferrocene based upon the Kubo–Anderson process is presented, which explains the observed spectra as superposition of three components: Static Ferrocene, anisotropic rotating Ferrocene and isotropic rotating Ferrocene.     

Angular distributions of scattered excited muonic hydrogen atoms

Coulomb deexcitation differential cross sections of excited muonic hydrogen in collisions with the hydrogen atom are studied for the first time. In the fully quantum-mechanical close-coupling approach, both the differential cross sections for the nl → n′l′ transitions and l-averaged differential cross sections have been calculated for the initial exotic atom states with n = 2–6 at kinetic energies of E _cm = 0.01–15 eV and for scattering angles of ϑ_cm = 0°–180°. The vacuum polarization shifts of the ns states are taken into account. The differential cross sections of the elastic and Stark scattering obtained in the same approach are also presented. The main features of the calculated differential cross sections are discussed, and a strong anisotropy of Coulomb deexcitation cross sections is predicted. The text was submitted by the authors in English.