Vibrational Structure of the B—X System of Isotopic Ago Molecules

Spectra of ¹⁰⁷Ag¹⁸O and ¹⁰⁷Ag¹⁶O molecules have been obtained in a low-pressure arc in oxygen atmosphere, and recorded with medium dispersion. Vibrational assignments for the bands of B ²π —X²π system were verified by the study of the oxygen isotope effect, and the vibrational constants were obtained for the states involved in transitions.     

Calculation of the IR Spectrum and the Molecular Structure of β-Carotene

Using the B3LYP/6-31G(d) method, calculations of the structure and the IR spectra of all-trans-β-carotene and its 15,15′-cis-isomer have been performed. The effective harmonic force fields have been obtained and the observed IR bands have been interpreted. Vibrations of the β-ionic ring have been singled out. On the basis of the analogy between the molecular structure of stable radicals and carotenoids of natural origin we set up the hypothesis that the methyl groups of the β-carotene molecule stabilizing the biradical excited triplet state that arises in the process of triplet-triplet energy transfer play a protective, screening role.__________Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 2, pp. 157–164, March–April, 2005.     

A Vibrational Spectroscopy Study of “Urinary Sand”

Laser Raman Spectroscopy and FT-IR spectroscopy are used for the study of “urinary sand”. The examination of Raman spectra indicates the presence of struvite and apatite in the sample. The FT-IR spectrum is used to evaluate the relative concentration of apatitebtruvite components in the sample. The form of band profile may be correlated to the history of particle growth.     

Molecular Dynamics Simulation of the Structure I Empty Gas Hydrate

The 368 water molecule structure I empty gas hydrates with three possible hydrogen orientations are calculated using TIP4P potential molecular dynamical simulations.The thermodynamic properties and hydrogen bonding are compared with ice Ih.The density of states is analysed based on experimental measurements.The empty gas hydrate at low temperature is stable without gas molecules encaged.     

Intermolecular Vibrational Coupling A Model Calculation for the Out-of-Plane Vibration of CO3 −- in Compounds with the Aragonite Structure

Abstract

¹³CO₃ ^?- substituted compounds with the aragonite structure show a fine structure of the out-of-plane vibration in the infrared spectra. A simple quantum mechanical model of coupled oscillators is developed to describe quantitatively the observed spectra. The spectra can be interpreted in terms of isolated ^12CO ₃ ^?- and ¹³CO₃ ^?- clusters, whose eigenfunctions interact. The heavy ions have localized vibrations, whereas clusters of the light ion with more than one ion show only localized vibrations at small coupling; stronger coupling results in resonant modes. Intensitytransfer from light to heavy ion bands is explained and the consequences of interaction between different clusters are discussed.     

Vibrational Distribution of Hydrogen Molecular Ions in High-Energy Ionization Processes

A theoretical time-dependent wave-packet dynamics method is applied to calculate the distribution of vibrational states of hydrogen molecular ions produced in high-energy ionization processes of hydrogen molecules. The isotope effect is elucidated in agreement with the available experimental measurements. Our proposed method should be readily applied in other atomic and molecular processes considering great advances in electronic computation science and technology.     

Algebraic Hamiltonian for Vibrational Spectra of Stibine

An algebraic Hamiltonian, which in a limit can be reduced to an extended local mode model by Law and Duncan, is proposed to describe both stretching and bending vibrational energy levels of polyatomic molecules, where Fermi resonances between the stretches and the bends are considered. The Hamiltonian is used to study the vibrational spectra of stibine (SbH3). A comparison with the extended local mode model is made. Results of fitting the experimental data show that the algebraic Hamiltonian reproduces the observed values better than the extended local mode model.     

A Time-Distinguished Analysis of the Harmonic Structure from a Model Molecular Ion

We present high-order harmonic generation spectra resulted from a single-electron model molecular ion exposed to intense laser fields by numerically solving a one-dimensional time-dependent Schrodinger equation. There are three plateaus in the spectra and the maximal cutoff energy is Ip 8.5Up, when the inter-nuclear distance R     

Influence of the Structure of Water–Alcohol Solutions of Dyes on Their Molecular Association

The spectral and luminescence characteristics of water and water–ethanol solutions of dyes have been investigated. The efficiency of the process of association of dye molecules and the structure of the complexes formed depending on their concentration and the solvent composition have been established. The presence of inhomogeneities in the distribution of dissolved complex molecules in the water matrix which determine the high efficiency of the association processes in water solutions as compared with other solvents is shown. The characteristic sizes of these inhomogeneities have been estimated.     

The MACQM Calculation for the BInding Energy of the Equilateral Triangle Structure of H3^— Cluster

Considering that the equilateral triangle structure of H3^- cluster can be formed from the interaction of H^- with two hydrogen atoms,a modified arrangement channel quantum mechanics method has been used to calculate the total energy curve for this structure,The result shows that the cureve has a minimal energy-1.6672 a.u.at an internuclear distance of 1.77a0,so its dissociation energy(binding energy)is D(H^- H H)=0.1395,a.u.This means that the cluster H3^- may be formed in an equilateral triangle structure with a bond length of 1.77α0.     

Vibrational Spectra of Ion–Molecular Carbonate Crystals in the Pretransition Region near Structural Phase Transitions

Optics and Spectroscopy - Molecular relaxation processes in lithium (Li2CO3), sodium (Na2CO3), and potassium (K2CO3) carbonates are studied by Raman spectroscopy. It is found that the first-order...     

Synthesis,Redetermination and Molecular Conformation Analysis of the Structure of 2,2′-Diaminodiphenyl Disulfide

A new synthesis and the crystal structure of C₁₂H₁₂N₂S₂ have been described and redetermined. In order to optimize the geometry of the molecule, the semi empirical methods MNDO, AMI and PM3 were used. The conformation of the energy profile showed that the minimum energy conformation has the torsion angle θ [Cl-Sl-Sl′-Cl′] near 90°. The energy barrier at 0° attributed to the lone pair repulsion of sulphur atoms and interactions between NH…S and H(C6)…S non-bonded atoms.     

On the Structure of the B¨acklund Transformations for the Relativistic Lattices

Abstract

The B¨acklund transformations for the relativistic lattices of the Toda type and their discrete analogues can be obtained as the composition of two duality transformations. The condition of invariance under this composition allows to distinguish effectively the integrable cases. Iterations of the B¨acklund transformations can be described in the terms of nonrelativistic lattices of the Toda type. Several multifield generalizations are presented.     

Recent Analytical Applications of Molecular Spectroscopy in Bioorganometallic Chemistry—Part I: Metal Carbonyls

Abstract: This is the first part of a two-part review on the analytical applications of molecular spectroscopy in bioorganometallic chemistry since 2005. In this case, radiopharmaceutical studies are included and the review is focused particularly on biological molecules labeled with metal carbonyl fragments.     

Vibrational Spectroscopy of Stretching and Bending Modes of Nickel Tetraphenyl Porphyrin： an Algebraic Approach

We calculate the vibrational frequencies of nickel tetraphenyl porphyrin for 36 vibrational bands by using the U（2） algebraic approach. The algebraic parameters in the calculations are accurate with the experimental data.     

Implications of unitarity and analyticity for the Dπ form factors

We consider the vector and scalar form factors of the charm-changing current responsible for the semileptonic decay D → πlν. Using as input dispersion relations and unitarity for the moments of suitable heavy-light correlators evaluated with Operator Product Expansions, including O(α _s ²) terms in perturbative QCD, we constrain the shape parameters of the form factors and find exclusion regions for zeros on the real axis and in the complex plane. For the scalar form factor, a low-energy theorem and phase information on the unitarity cut are also implemented to further constrain the shape parameters. We finally propose new analytic expressions for the Dπ form factors, derive constraints on the relevant coefficients from unitarity and analyticity, and briefly discuss the usefulness of the new parametrizations for describing semileptonic data.