Search results for "COHERENT"
showing 10 items of 303 documents
Acousto-Plasmonic Hot Spots: Driving Enhanced Raman Scattering in Metallic Nanoparticles
2010
We study theoretically and experimentally the coupling of acoustic vibrations (phonons) and surface plasmons in metallic nano-objects. The modulation of the surface charge density allows for the interpretation of experimental Raman-Brillouin spectra in silver nanorods.
Shot-by-shot frequency calibration of CARS spectra: Application to the measurement of the collisional line shift in oxygen
1996
A technique using a Fabry-Perot interferometer has been developed to calibrate high-resolution spectra obtained by Coherent Anti-Stokes Raman Spectroscopy (CARS). This technique was used to measure simultaneously the Raman frequency and the Raman signal at each laser shot. We demonstrate the accuracy of the method by measuring theQ(15) line shifts of molecular oxygen due to collisions with oxygen and water vapour.
Polarized and resonant Raman spectroscopy on single InAs nanowires
2011
We report polarized Raman scattering and resonant Raman scattering studies on single InAs nanowires. Polarized Raman experiments show that the highest scattering intensity is obtained when both the incident and analyzed light polarizations are perpendicular to the nanowire axis. InAs wurtzite optical modes are observed. The obtained wurtzite modes are consistent with the selection rules and also with the results of calculations using an extended rigid-ion model. Additional resonant Raman scattering experiments reveal a redshifted E1 transition for InAs nanowires compared to the bulk zinc-blende InAs transition due to the dominance of the wurtzite phase in the nanowires. Ab initio calculatio…
Silicon nitride-based deep sub-λ slit for ultra-broadband THz coherent detection
2018
We report on the characterization of a new type of CMOS-compatible device for terahertz solid-state biased coherent detection, which relies on a 1-µm-wide metallic slit embedded in a thin film of PECVD-grown silicon nitride.
Transverse chemical interface detection with coherent anti-Stokes Raman scattering microscopy
2011
International audience; Transverse "chemical" interfaces are revealed with a conventional two beam narrowband coherent anti-Stokes Raman scattering microscopy setup in a collinear configuration. The exciting "pump" and "Stokes" beams are focused on the sample in two opposite directions. The subtraction of the two generated anti-Stokes signals gives rise to a signal that is directly proportional to the pure Raman spectrum of the resonant medium. This property is used to highlight an interface between glass and N,N-dimethylformamide (DMF) and recover the pure Raman spectrum of DMF around its 1408 cm−1 vibrational band.
Strong enhancement of the Breit-Wigner-Fano Raman line in carbon nanotube bundles caused by plasmon band formation
2002
We investigate the origin of the Breit-Wigner-Fano line in the Raman spectra of individual single-walled carbon nanotubes and their bundles. Using confocal Raman microscopy and atomic-force microscopy we found that the Breit-Wigner-Fano line intensity increases strongly with the bundle thickness. We confirmed this result by Raman investigations of partially decomposed bundles, which were additionally investigated by transmission electron microscopy. Our random-phase approximation based theory, which identifies the Breit-Wigner-Fano line as an excited band of plasmon-phonon modes, is fully consistent with the experimental results.
Femtosecond Raman time-resolved molecular spectroscopy
2004
Abstract The applicability of several femtosecond time resolved non-linear coherent techniques such as Raman induced polarization spectroscopy (RIPS), degenerate four-wave mixing (DFWM) and coherent anti-Stokes Raman spectroscopy (CARS) for molecular spectroscopy is presented. All methods rely on the initial coherent excitation of molecular states producing wavepackets, whose time evolution is then measured. In the case of RIPS and DFWM only pure rotational transitions are involved, whereas in CARS vibrational states can be excited. First the methodology of concentration and temperature measurements using RIPS in gas mixtures involving N2, CO2, O2, and N2O is shown. In addition some applica…
Comment on “Infrared and Raman selection rules for elastic vibrations of spherical nanoparticles”
2006
This Comment demonstrates again that selection rules established several years ago for the infrared absorption and the Raman scattering by vibrations of a spherical nanoparticle are correct and that the claimed errors about them are wrong.
Seeing a single molecule vibrate through time-resolved coherent anti-Stokes Raman scattering
2014
The vibrations of the chemical bonds of a single molecule are observed by employing time-resolved coherent anti-Stokes Raman scattering. A gold nanoantenna is used to enhance the signal from the molecule.
Alignment-free, all-spliced fiber laser source for CARS microscopy based on four-wave-mixing
2012
An environmentally-stable low-repetition rate fiber oscillator is developed to produce narrow-bandwidth pulses with several tens of picoseconds duration. Based on this oscillator an alignment-free all-fiber laser for multi-photon microscopy is realized using in-fiber frequency conversion based on four-wave-mixing. Both pump and Stokes pulses for coherent anti-Stokes Raman scattering (CARS) microscopy are readily available from one fiber end, intrinsically overlapped in space and time, which drastically simplifies the experimental handling for the user. The complete laser setup is mounted on a home-built laser scanning microscope with small footprint. High-quality multimodal microscope image…