Search results for "raman scattering"
showing 10 items of 284 documents
Observation and analysis of Fano-like lineshapes in the Raman spectra of molecules adsorbed at metal interfaces
2015
Surface enhanced Raman spectra from molecules (bipyridyl ethylene) adsorbed on gold dumbells are observed to become increasingly asymmetric (Fano-like) at higher incident light intensity. The electronic temperature (inferred from the anti-Stokes (AS) electronic Raman signal increases at the same time while no vibrational AS scattering is seen. These observations are analyzed by assuming that the molecule-metal coupling contains an intensity dependent contribution (resulting from light-induced charge transfer transitions as well as renormalization of the molecule metal tunneling barrier). We find that interference between vibrational and electronic inelastic scattering routes is possible in …
Raman scattering in hcp rare gas solids under pressure
2008
We present Raman measurements of hcp rare gas solids (RGSs) at megabar pressures together with lattice dynamics calculations. The ${E}_{2g}$ phonon was measured in Xe up to metallization near 135 GPa and in Ar up to 58 GPa. A comparative analysis of first-principles and semiempirical calculations shows that three-body forces contribute to the energetics at low pressures and that at volume compressions greater than $\ensuremath{\sim}2.6$ higher-order many-body forces become important. The distinct behavior of He under pressure relative to that of the rest of the RGS family is discussed.
Electronic and vibrational properties of meso-tetraphenylporphyrin on silver substrates.
2014
The electronic and vibrational properties of meso-tetraphenylporphyrin (mtpp) on silver substrates are investigated using UV–vis and surface-enhanced resonance Raman scattering (SERRS) spectroscopy. Whereas the vibrational signatures associated with the tetrapyrrole backbone exhibit minor variations throughout sequences of consecutively recorded SERRS spectra, the C═C stretching vibrational modes localized on the meso-phenyl moieties of mtpp exhibit noticeable intensity fluctuations, masked in the average SERRS response. We attribute the observed vibrational-state-specific blinking events to conformational changes in mtpp, namely, torsional flexibility which mediates the coupling between th…
Nuclear Resonance Scattering Using Synchrotron Radiation (Mössbauer Spectroscopy in the Time Domain)
2010
Conventional Mossbauer spectroscopy (MS) can be considered as “spectroscopy in the energy domain.” It has been widely used since its discovery in 1958 [1]. Nuclear resonant forward scattering (NFS) of synchrotron radiation has been successfully employed as a time-differential technique since 1991 [2]. Another related technique, nuclear inelastic scattering (NIS) of synchrotron radiation [3], can be regarded as an extension of conventional, energy-resolved MS (in the range 10−9 to 10−7 eV) to energies on the order of molecular vibrations (in the range 10−3 to 10−1 eV). So far only a few “Mossbauer” stations for NFS and NIS measurements have become available in synchrotron laboratories, i.e.,…
Broadband stimulated Raman backscattering
2016
International audience; Broadband amplification employing stimulated Raman backscattering is demonstrated. Using seed pulses with a bandwidth of about 200 nm, we study the amplification in a wide spectral range in a single laser shot. With chirped pump pulses and a Ne gas jet, we observed under optimized conditions, amplification in a range of about 80 nm, which is sufficient to support the amplification of sub-20 fs pulses. This broad amplification range is also in excellent agreement with PIC simulations. The conversion efficiency is at certain wavelengths as high as 1.2% and was measured to be better than 6×10 −3 on average.
Incoherent Dispersive Shocks and Spectral Collapse
2014
We predict the existence of incoherent dispersive shock waves and collapse-like singularities that occur in the spectral evolution of incoherent optical waves propagating in a noninstantaneous nonlinear medium.
Spectral long-range interaction of temporal incoherent solitons.
2014
We study the interaction of temporal incoherent solitons sustained by a highly noninstantaneous (Raman-like) nonlinear response. The incoherent solitons exhibit a nonmutual interaction, which can be either attractive or repulsive depending on their relative initial distance. The analysis reveals that incoherent solitons exhibit a long-range interaction in frequency space, which is in contrast with the expected spectral short-range interaction described by the usual approach based on the Raman-like spectral gain curve. Both phenomena of anomalous interaction and spectral long-range behavior of incoherent solitons are described in detail by a long-range Vlasov equation.
Accurate spectroscopic constants of nitrogen determined from stimulated Raman spectra of the fundamental and first hot bands
1990
Nitrogen spectra of the Q-branch of the fundamental and the first hot bands were recorde with a high-resolution stimulated Raman spectrometer at atmospheric pressure and ca. 1300 K. The absolute frequencies of the Raman lines were measured with high accuracy, leading to a refinement of spectroscopic constants. A temperature estimation was also performed from the Raman intensities.
Investigation of the epitaxy of thin YBa2Cu3O7-delta films
1990
Abstract The degree of epitaxy of thin sputtered and laser ablated films have been investigated by Raman spectroscopy. Using the selection rules for Raman scattering for the different phonons in YBa 2 Cu 3 O 7−δ the superconducting films on SrTiO 3 and MgO are found to be epitaxially grown with the c -axis perpendicular to the substrate. On ZrO 2 the films also grow with their c -axis perpendicular to the substrate, but with randomly oriented a / b -directions in the plane of the film.
Raman scattering studies of ultrathin-layer YBa2Cu3O7/PrBa2Cu3O7 superlattices
1994
We present Raman scattering studies ofc-oriented ultrathin-layer superconducting (YBa2Cu3O7) m /(PrBa2Cu3O7) n superlattices. For the superlattice with (m=2,n=1) sequence, Raman spectra reveal a new line in the spectral region around 320 cm−1. It is interpreted as a mode representing a combination of IR optical phonons of the Y-sublayers with an admixture of aB1g type Raman active vibration in the Pr sublayers. This new line, which is similar to those from the interior of the Brillouin zone of the original lattice, does not exhibit superconductivity-induced self-energy effects, although its counterpart in the pure substance does. No additional line is found in the (m=1,n=2) superlattice in …