Search results for "RAMAN"
showing 10 items of 1328 documents
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…
Multi-frequency near-field enhancement with graphene-coated nano-disk homo-dimers.
2019
In this paper, a 3D sub-wavelength graphene-coated nano-disk dimer (GDD) is proposed for multi-frequency giant near-field enhancement. We observed that the dual-band operation originates from the excitation of hybridized localized surface plasmons on top and bottom faces of the disks along with the mutual coupling from the adjacent particle. Due to the sub-wavelength nature of the disks, the excited localized surface plasmons on the sidewalls are weak but they still can affect the dual operating bands. On the other hand, the strength and resonance frequency of the enhanced fields can be simply modulated by tuning the relative distances of 2D graphene disks on top and bottom faces. Adjustabl…
Raman Studies of Photorefractive Lithium Niobate Single Crystals
2014
A study of Raman spectra of lithium niobate single crystals: stoichiometric, ostensibly pure congruent LiNbO3, and congruent LiNbO3 containing admixture of yttrium is reported. Raman bands observed in spectra excited by visible laser radiation are thoroughly compared to the same bands excited by infrared laser radiation. The broadening of Raman bands excited by radiation of shorter wavelengths is attributed to photo-refraction induced by visible radiation (514 nm) while being absent under infrared radiation (1064 nm). Attributing the effect of photo-refraction to radiation-induced structural changes in the illuminated part of the crystal lattice the authors interpret the observed broadening…
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.
Structural and Optical Homogeneity in Lithium Niobate Crystals of Low Photorefractivity
2015
Comprehensive studies by Raman and photo-induced light scattering complemented by laser conoscopy and electron spectroscopy of structural and optical homogeneity of nominally pure and modified lithium niobate crystals are reported.
Combination of Confocal Raman Spectroscopy and Electron Microscopy on the Same Individual Bundles of Single-Walled Carbon Nanotubes
2002
We report a method to investigate the same individual single-walled carbon nanotube (SWNT) bundles with both transmission electron microscopy (TEM) and Raman spectroscopy. Free-standing individual bundles are obtained by depositing a solution of suspend SWNTs on a carbon film with a regular pattern of holes, which can be localized by TEM and also by confocal Raman microscopy. While most of the TEM images predict that the bundles consist of tubes with a similar diameter, we will show that occasionally a certain tube diameter can be associated with a particular radial breathing mode frequency of the Raman spectrum. Single-walled carbon nanotubes (SWNTs) are one-dimensional molecular structure…
Erratum: Polarized and resonant Raman spectroscopy on single InAs nanowires (vol 84, 085318, 2011)
2012
We found out that the polar pattern for the zinc-blende InAs LO mode displayed in Fig. 2(b) of our original paper represents the backscattering Raman intensities from a (11¯2) top surface and not as stated in the original manuscript from a (110) top surface.In the latter the LO mode is forbidden for all configurations.
Acousto-plasmonic coupling in engineered metal nanocomposites
2010
This work shows the production of self-assembled elongated nano-objects embedded in an oxide host oriented perpendicular to the substrate and their acousto-plasmonic dynamics. Electromagnetic “hot spots” are created that activate anomalous Raman vibrational modes.
Raman spectra of (PbS)1.18(TiS2)2 misfit compound
2007
Abstract A Raman study on the (PbS)1.18(TiS2)2 semiconductor structure with incommensurate layers (misfit) is reported. The different bands observed in the spectra are attributed to both the TiS2 host layers, at 219 (Eg) and 333 (A1g) cm−1, and the intercalated PbS layers: the LO(Γ), 2LO and 3LO phonons at 203, 412 and 634 cm−1, respectively. A phonon peak probably related to the superposition of TiS2 and PbS vibrations, was observed near 286 cm−1. The decrease of the phonon wave numbers (of the modes located at 203, 333, 412, and 634 cm−1) with increasing laser power pointed out negative temperature coefficients of these modes. A peak appearing with laser power near 151 cm−1 is discussed. …
High-harmonic km-long self-pulsed Raman fiber laser
2011
Raman all-fiber lasers have attracted considerable interest during the past two decades due to their convenient use and extended wavelength coverage when compared to rare-earth-doped fiber lasers. Still, little is known about their potential as pulsed laser sources. Mode locked Raman fiber lasers have been demonstrated quite recently [1,2], as well as harmonic mode-locking with a record of 500,000 intra-cavity pulses in a dissipative four-wave mixing configuration using a fiber Bragg grating [3].