Search results for "COHERENT"
showing 10 items of 303 documents
High-resolution stimulated Raman spectroscopy of O2
1992
Abstract The S S and O O branches of the fundamental vibrational band of molecular oxygen in its electronic ground state have been resolved for the first time in Raman spectroscopy. The spectra have been observed, at room temperature and low pressure, with a stimulated Raman scattering (S.R.S.) spectrometer including a multipass cell. From these accurate Raman data combined with microwave data, we have improved the values of the vibrational, rotational, spin-spin, and spin-rotation interactions constants in the v = 1 vibrational state. Moreover, Raman Q branches of the first and second hot-bands have been recorded, allowing us to determine a set of molecular parameters for the v = 2 and v =…
Using Dynamic Light Scattering for Monitoring the Size of the Suspended Particles in Wastewater
2019
Abstract A coherent light scattering experiment on wastewater samples extracted from several stages of water processing within a wastewater processing plant was carried out. The samples were allowed to sediment while they were the subject of a Dynamic Light Scattering (DLS) measurement. The recorded time series were processed using an Artificial Neural Network based DLS procedure to produce the average diameter of the particles in suspension. The method, using a single physical procedure for monitoring the variation of the average diameter in time, indicates the dominant type of suspensions in water.
Polarized multiplex coherent anti-Stokes Raman scattering using a picosecond laser and a fiber supercontinuum
2011
International audience; We perform multiplex coherent anti-Stokes Raman scattering (CARS) micro-spectroscopy with a picosecond pulsed laser and a broadband supercontinuum (SC) generated in photonic crystal fiber. CARS signal stability is achieved using an active fiber coupler that avoids thermal and mechanical drifts. We obtain multiplex CARS spectra for test liquids in the 600–2000 cm−1 spectral range. In addition we investigate the polarization dependence of the CARS spectra when rotating the pump beam linear polarization state relative to the linearly polarized broad stokes SC. From these polarization measurements we deduce the Raman depolarization ratio, the resonant versus nonresonant …
Electronic structure and optical, mechanical, and transport properties of the pure, electron-doped, and hole-doped Heusler compound CoTiSb
2012
The Heusler compound CoTiSb was synthesized and investigated theoretically and experimentally with respect to electronic structure and optical, mechanical, and vibrational properties. The optical properties were investigated in a wide spectral range from 10 meV to 6.5 eV and compared with ab initio calculations. The optical spectra confirm the semiconducting nature of CoTiSb, with a strong exciton absorption at 1.83 eV. The calculated phonon dispersion as well as elastic constants verify the mechanical stability of CoTiSb in the cubic $C{1}_{b}$ system. Furthermore, solid solution series of CoTi${}_{1\ensuremath{-}x}$${M}_{x}$Sb ($M=\text{Sc}$, V and $0\ensuremath{\leqslant}x\ensuremath{\le…
Secondary relaxation in the glass-transition regime of ortho-terphenyl observed by incoherent neutron scattering.
1992
We report on incoherent-neutron-scattering measurements in the supercooled regime of the van der Waals liquid ortho-terphenyl. A secondary localized relaxational process on the picosecond time scale is found. In accordance with mode-coupling theories of the glass transition, the relaxational dynamics around a critical temperature ${\mathit{T}}_{\mathit{c}}$ decomposes into two time regimes.
Alloying experiments on heavy fermion compounds
1990
Abstract This paper is intended to demonstrate the usefulness of controlled alloying for the understanding of heavy-fermion physics: (1) Th-substitution for Ce in CeCu2Si2 emphasizes the dominating role of the dopant-induced strain fields in generating incoherent scattering and pair breaking, (2) replacement of Cu by Ni in Ce(Cu1-xNix)2Ge2 leads to phenomena which are interpreted as derived from a transition between local-moment and itinerant heavy-fermion magnetism, and (3) increasing Cu concentration in UCu4+xAl8-x is accompanied by an antiferromagnetic to nonmagnetic transition near xcr = 1.5 similar to what has been found before for several Ce-based systems. A heavy Fermi-liquid phase w…
Temperature-dependent resistivity and anomalous Hall effect in NiMnSb from first principles
2019
We present implementation of the alloy analogy model within fully relativistic density-functional theory with the coherent potential approximation for a treatment of nonzero temperatures. We calculate contributions of phonons and magnetic and chemical disorder to the temperature-dependent resistivity, anomalous Hall conductivity (AHC), and spin-resolved conductivity in ferromagnetic half-Heusler NiMnSb. Our electrical transport calculations with combined scattering effects agree well with experimental literature for Ni-rich NiMnSb with 1--2% Ni impurities on Mn sublattice. The calculated AHC is dominated by the Fermi surface term in the Kubo-Bastin formula. Moreover, the AHC as a function o…
Fast Local Motion around T g in a Molecular Glass as Observed by Incoherent Neutron Scattering
1987
Incoherent quasi-elastic neutron scattering experiments on a molecular glass (1,3,5-tri-α-naphtylbenzene, C36H24) are reported. We find clear evidence for an anomalously strong decrease of the elastic and a corresponding increase of the inelastic scattering around the glass transition temperature. The line shape of this extra inelastic intensity gives evidence for a quasi-elastic scattering implying the existence of a localized and fast (τc ≈ 4.10-12s) molecular motion. From the elastic incoherent structure factor (EISF) a mean jump length ≤ 0.6 A is estimated. The significance of this motion as precursor of the glass instability is discussed within the framework of dynamic glass transition…
Phonon Bridge Effect in Superlattices of Thermoelectric TiNiSn/HfNiSn With Controlled Interface Intermixing
2020
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