Rovibrational analysis of the absorption spectrum of H2O around 1.02 μm by ICLAS-VECSEL

The very weak water vapor absorption spectrum has been investigated between 9520 and 10 010 cm⁻¹ by intracavity laser absorption spectroscopy based on a vertical external cavity surface emitting laser. The rovibrational assignment performed on the basis of the ab initio calculations of Schwenke and Partridge has allowed for determining 156 new energy levels belonging to a total of 13 vibrational states. The assignment process is detailed. The results are compared with the available databases and discussed in regard of recent investigations by Fourier transform spectroscopy.     

High-Order Resonances in the Water Molecule

The water-vapor spectra in the near-infrared and visible region were reanalyzed with the purpose of finding experimental evidences of unusual high-order resonance between "dark" high-bending and "bright" stretch vibration states. About 70 transitions to the (050), (060), (070), (080), (160), (061), (170), (071), and, even (0 10 0) bending states, and their resonating partners were assigned in the spectra that gives the experimental energy levels lying near or above the potential energy barrier to linearity. The assignments were confirmed by combination differences and simultaneous observation of both perturbed and perturbing levels. It was found that the high-order resonances with large changing of vibration quantum numbers are typical for the water molecule and they are caused by the strong centrifugal distortion near the linear configuration. These resonances destroy the usual polyad scheme originating from well-known Coriolis, Darling-Dennison, and Fermi resonances in H(2)O molecule. Copyright 2001 Academic Press.     

Investigation of the spectral and angular distribution of gamma radiation of ultrarelativistic electrons in crystals

A technique and experimental apparatus are described for measuring the properties of radiation from relativistic electrons in crystals as a function of frequency and angle. The results of these measurements are compared with calculations and with the results obtained by other workers.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 54–62, June, 1991.     

An expert system for identification of lines in vibrational-rotational spectra

An expert system for automatic identification of the complex vibrational-rotational spectra of molecules has been developed. An iteration approach is implemented in this system, in which employment of the exact combination rule is combined with determination of the spectroscopic constants by solving of the inverse problems and comparison of the calculated parameters of spectral lines with the corresponding measured values. In order to calculate the energy levels and the frequencies and intensities of lines, the Watson Hamiltonian, the Padé-Borel approximants, and generating functions are used. The system is based on the application of pattern-recognition algorithms. Recognition training makes it possible to obtain the required flexibility of the system and to use different methods of identification based on the application of combination rules both for the analysis of strong bands and for the assignment of weak single lines. The system developed can be used to analyze the spectra of the C _s and C _2V molecules, as well as employ the calculated spectrum of a molecule of any type prepared in advance. This system was successfully used to identify the H ₂ ¹⁶ O, H ₂ ¹⁷ O, H ₂ ¹⁸ O, D₂O, HDO, H ₂ ³² S, H ₂ ³⁴ S, and H ₂ ³³ S and molecules.     

Estimation of the σR-constants of the tetrazolyl groups on the basis of13C NMR spectra of vinyltetrazoles

On the basis of¹³C NMR spectra of tetrazole-containing vinyl monomers, the resonance _R constants of a series of tetrazolyl groups have been estimated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 236–237, February, 1987.The authors thank E. V. Borisov for his help in taking the NMR spectra.     

Generation of diversiform gold nanostructures inspired by honey's components: Growth mechanism, characterization, and shape separation by the centrifugation-assisted sedimentation

The green synthesis of irregular-shaped nanomaterials used for various applications in nanoplasmonics, medicine, and biotechnology creates an economical and environmental challenge. We describe the rapid wet-chemical approach to synthesis of stable and water-soluble gold nanostructues at room temperature. In addition to spherical and road-like nanoparticles, gold decahedra and triangular plates were grown using the one-step synthesis process of HAuCl(4) in the presence of honey, in which main components act as reducing (glucose) and stabilizing (fructose) agents; the mechanism of the process is discussed in details. The requirements for anisotropic phase boundaries for generation of polyhedral gold nanocrystals in solutions are highlighted. The synthesis, morphology, and separation procedure of gold nanoparticles are examined using the techniques of optical spectroscopy, transmission electron microscopy, and atomic force microscopy. We demonstrate that centrifugation can be used for efficient separation of nanoparticles with different shapes from a mixture. It was found that while centrifuging, the spheres sediment at the bottom of the tube, segregating from rods that form a deposit on the side wall, whereas polygons remain in the solution.     

Multidimensional Langevin approach to description of near-barrier heavy-ion fusion and deep-inelastic collisions

A six-dimensional Langevin approach is developed for the analysis of near-barrier heavy-ion fusion and deep-inelastic collisions. In its framework, vibrational and rotational degrees of freedom of both nuclei are taken into account explicitly. Calculated fusion cross sections, compound nuclei spin distributions, and angular and energy distributions of deep-inelastic products show satisfactory agreement with experimental data.     

High-Order Resonance Interactions in HDO: Analysis of the Absorption Spectrum in the 14 980-15 350 cm(-1) Spectral Region

The absorption spectrum of the HDO molecule recorded by intracavity laser absorption spectroscopy in the 14 980-15 350 cm(-1) spectral region was assigned and modeled in the frame of the effective Hamiltonian approach. The spectrum (496 lines) results, mainly, from transitions to the rotational sublevels of the (014) bright state. An important number of transitions involving the (142) and (0 12 0) highly excited bending states could be identified, borrowing their intensities through high-order resonance interactions with the (014) state. An original feature shown by the present analysis is that all the transitions involving unperturbed energy levels of the (014) state are exclusively of A type, while both A- and B-type transitions are observed when the upper states are perturbed by the resonance interactions. One hundred forty-five energy levels of the three interacting states were derived from the spectrum and fitted to the effective rotational Hamiltonian in Pade-Borel approximants form with 29 varied parameters yielding an rms deviation of 0.038 cm(-1). A few energy levels are affected by additional local resonances with perturbers which have been identified. Finally, 48 transitions of the very weak 6nu(1) band were assigned and fitted as an isolated band. Copyright 2000 Academic Press.