Search results for "ROTATIONAL"
showing 10 items of 381 documents
Neutron Radiography Visualization of Solid Particles in Stirring Liquid Metal
2015
Abstract This paper presents the analysis of the first dynamic neutron radiography experiment that visualized motion of solid particles in liquid metal, which was stirred by a system of four counter-rotating magnets. The paper also contains the quantitative results derived from neutron images: the distribution of particle concentration, number of admixed particles and velocities as functions of the magnet rotation speed.
Temperature measurement in gas mixtures by femtosecond Raman-induced polarization spectroscopy
2003
European Conference on Nonlinear Optical Spectroscopy (ECONOS) MAR 30-APR 01, 2003 BESANCON, FRANCE; The potential of femtosecond Raman-induced polarization spectroscopy (RIPS) for the simultaneous determination of temperature and concentrations was investigated. These measurements were related to the rotational time response of the molecular gas mixture, which was measured as a function of the pump-probe time delay. The change of the polarizability anisotropy with respect to the vibrational levels was taken into account. The results of temperature measurements in pure CO2 showed good agreement with the values obtained by a thermocouple. The RIPS technique was also applied to a CO2-N2 gas m…
Trapped Ion Oscillation Frequencies as Sensors for Spectroscopy
2010
The oscillation frequencies of charged particles in a Penning trap can serve as sensors for spectroscopy when additional field components are introduced to the magnetic and electric fields used for confinement. The presence of so-called "magnetic bottles" and specific electric anharmonicities creates calculable energy-dependences of the oscillation frequencies in the radiofrequency domain which may be used to detect the absorption or emission of photons both in the microwave and optical frequency domains. The precise electronic measurement of these oscillation frequencies therefore represents an optical sensor for spectroscopy. We discuss possible applications for precision laser and microw…
Spherical Top Theory and Molecular Spectra
2011
In this article, we present an overview of the present state of the art of the theory of high-resolution spherical-top spectra in the framework of the effective Hamiltonian approach. We describe the specific features of this class of molecules to explain the basic concepts of the theoretical methods used for the analysis (line positions and intensities) and the simulation of absorption (including pure rotation) and Raman spectra of such species. The non conventional formalism that we use is essentially based on irreducible tensor methods and is especially adapted to computational treatments and global analyses of complex interacting band systems. We give examples concerning mainly methane (…
Rotational collisional line broadening at high temperatures in the N2 fundamental Q-branch studied with stimulated Raman spectroscopy
1986
Self broadened N 2 Q-branch spectra are measured by high resolution stimulated Raman spectroscopy in the pressure region 0.25-1.9 atm. and in the temperature range 295-1310 K. Non additivity of the Q(J) components due to line overlap arising in the highest pressure range explored is carefully taken into account. Excellent fit of the whole spectra is thus obtained for each pressure with linearly density-dependent line widths. Semi-classical calculations of the line-broadening coefficients lead to consistent values with all the measured ones. These calculations are extended to higher J values and to higher temperatures (up to 2500 K). At last, a simple phenomenological model based on a polyno…
Collisional Relaxation Processes Studied by Coherent Raman Spectroscopy for Major Species Present in Combustions
1992
The effects of collisional relaxation processes on the Q-branch profile of major species present in combustions have been studied by high resolution stimulated Raman spectroscopy. Particular interest has focused on the following collisional systems: N2-N2, O2-O2, CO2-CO2, O2-N2, N2-CO2 and N2-H2O. For each colliding pair, starting from accurate determinations of line broadening coefficients over a wide temperature range, state-to-state rates for rotational energy transfers have been deduced by using various fitting laws. Among these rate laws, special attention has been paid to the temperature dependence of the energy corrected scaling (ECS) law combined with a hybrid exponential-power law …
ChemInform Abstract: Cyclic SiS2: A New Perspective on the Walsh Rules.
2012
Cyclic SiS2 is detected in the low-current dc discharge products of a mixture of SiH4 and H2S by Fourier transform microwave spectroscopy.
High Resolution Coherent Raman Spectroscopy: Studies of Molecular Structures
1992
One of the main advantages of the non-linear coherent Raman techniques is the high resolution that can be achieved in rovibrational spectroscopy. Typically an instrumental function of the order of several thousandths of a wavenumber is routinely achieved in SRS or CARS experiments. Since the first recording of the stimulated Raman spectrum of 12CH4 in 1978 [1], numerous studies of molecules have been performed [2–8]. We have built a stimulated Raman experiment in Dijon in which particular attention has been paid to the frequency measurement of the Raman lines [9]. We will describe the application of our experiment to a wide variety of molecules over the last few years: linear molecules, sph…
Vibrational Perturbations and Ligand–Layer Coupling in a Single Crystal of Au144(SC2H4Ph)60 Nanocluster
2015
We have determined vibrational signatures and optical gap of the Au144(PET)60 (PET: phenylethylthiol, SC2H4Ph) nanocluster solvated in deuterated dichloromethane (DCM-D2, CD2Cl2) and in a single crystal. For crystals, solid-state (13)C NMR and X-ray diffraction were also measured. A revised value of 2200 cm(-1) (0.27 eV) was obtained for the optical gap in both phases. The vibrational spectra of solvated AU144(PET)60 closely resembles that of neat PET, while the crystalline-state spectrum exhibits significant inhomogeneous spectral broadening, frequency shifts, intensity transfer between vibrational modes, and an increase in the overtone and combination transition intensities. Spectral broa…
Three-dimensional core-collapse supernovae with complex magnetic structures: I. Explosion dynamics
2021
Magnetic fields can play a major role in the dynamics of outstanding explosions associated to violent events such as GRBs and hypernovae, since they provide a natural mechanism to harness the rotational energy of the central proto-neutron star and power relativistic jets through the stellar progenitor. As the structure of such fields is quite uncertain, most numerical models of MHD-driven core-collapse supernovae consider an aligned dipole as initial magnetic field, while the field's morphology can actually be much more complex. We present three-dimensional simulations of core-collapse supernovae with more realistic magnetic structures, such as quadrupolar fields and, for the first time, an…