Shape of Molecular Infrared Absorption and Raman Scattering Lines as Probe of Hindered Molecular Motion and Site Symmetry in Crystals

New symmetrized angular auto-correlation functions (ACFs) are applied to the theoretical description of the line-shape of internal modes in the polarized light scattering and infrared absorption spectra of molecular crystals. The model of hindered molecular motion (HMM) used to simulate the ACFs involves a molecular rearrangement by means of random angular jumps of an intramolecular vector between its hindered states in different potential wells whereas the probability density of the vector orientation is continuously distributed over the angles. The hindered states are classified according to the irreducible representations of a point symmetry group of the molecule motion. The ACFs of first and second ranks, which are important in molecular spectroscopy, are presented in an explicit form as a function of the crystal orientation in an axial laboratory coordinate frame. They depend on both the motion and site symmetry of the molecule through the correlation times and dynamic weights of the hindered states, respectively. The quantitative data important for practical applications are tabulated. The surface-plot graphs drawn for the initial amplitude of the ACFs show how an ACF anisotropy varies on changing the dynamic weights. The polycrystalline ACFs are in an agreement with the ACFs corresponding to rotation diffusion models. Therefore, the present theory of HMM can be considered as a general one and can be used in a description of the line extension caused by HMM in condensed matter. Some well known experiments on infrared, Raman and Rayleigh spectroscopy in molecular monocrystals and liquids show the reliability of the theory. © 1998 John Wiley & Sons, Ltd

Experimental study of an impulse electric discharge with liquid electrodes

© 2017, Pleiades Publishing, Ltd.Experimental results are presented on transition of a streamer shape multichannel discharge into a multichannel spark discharge. We present current–voltage characteristics of a multichannel streamer discharge at atmospheric and reduced pressures as well as temperature distribution between a plate-like copper electrode and technical water

The theory of hindered molecular motion and its application to spectroscopic studies

A stochastic theory of the classical local hindered motion of small molecules in molecular and ionic crystals is presented in detail. The so-called extended angular jump model, being intermediate between the rotational diffusion model and the model of fixed angular jumps, approximates the motion. In spite of the fact that dynamical quantities of the model do not relate to the hydrodynamic parameters of the continuous medium, the outcomes of the theory are suitable for molecular liquids. Two crystallographic point symmetries, the symmetry of the molecular motion and the site symmetry, including their distortions, are taken into account in the model. Applications of the theory to the description of NMR-relaxation rates and the homogeneous broadening of spectral lines excited by dielectric, infrared, Raman, Rayleigh and neutron spectroscopy techniques are given. The validity of the approach presented is confirmed by the experimental data performed in single crystalline and powder samples. © 2010 Taylor & Francis

Some peculiarities of electric discharge between a solid electrode and technical water

© 2016, Pleiades Publishing, Ltd.We present the results of experimental study of the electric discharge between metal electrodes of various geometry and technical water within the pressure range of 8 × 103–105 Pa at the saw-tooth voltage generator frequency, f = 40 MHz, and the interelectrode distance, l = 3–30 mm. We consider transfer of the streamer discharge into spark one depending on the geometry of the metal electrode and its material. We investigate the electrical characteristics of the discharge between the plate electrode and the technical water within a wide pressure range. The essential influence of the streamer discharge type on the ozone release within the investigated parameters range is discovered

Thermograms of High-Frequency Capacitive Discharge Between Solid and Liquid Electrodes

© 2018, Pleiades Publishing, Inc. Abstract: We present the experimental results on thermograms and plots of temperature distributions along the streamer and spark discharges in a high-frequency capacitive field between solid and liquid electrodes for different electrode geometries

Peculiarities of microwave discharge between a copper pin electrode and technical water

© 2014, Pleiades Publishing, Ltd. Some experimental results on burning of the microwave discharge between a copper pin electrode and technical water, in air, are presented within the ranges of the voltage U = 28–75 kV, the frequency f = 40–100 MHz, and the interelectrode space l = 2–20 mm. The essential influence of the pulse repetition frequency and the interelectrode space on the development, the shape, and the structure of the microwave discharge between the copper electrode and the technical water is revealed. Also the transition of the weakly glowing microdischarges inside the microwave discharge into the multichannel spark discharge is revealed. A temperature decrease below room temperature in the interelectrode gap of the microwave discharge with the technical water is discovered

Acute Coronary Syndrome and Ischemic Heart Disease in Pregnancy: Data From the EURObservational Research Programme-European Society of Cardiology Registry of Pregnancy and Cardiac Disease

Background The prevalence of ischemic heart disease (IHD) in women of child-bearing age is rising. Data on pregnancies however are scarce. The objective is to describe the pregnancy outcomes in these women. Methods and Results The European Society of Cardiology-EURObservational Research Programme ROPAC (Registry of Pregnancy and Cardiac Disease) is a prospective registry in which data on pregnancies in women wit