Search results for "RAMAN"

Peregrine soliton generation and breakup in standard telecommunications fiber

2011

International audience; We present experimental and numerical results showing the generation and breakup of the Peregrine soliton in standard telecommunications fiber. The impact of non-ideal initial conditions is studied through direct cut back measurements of the longitudinal evolution of the emerging soliton dynamics, and is shown to be associated with the splitting of the Peregrine soliton into two subpulses, with each subpulse itself exhibiting Peregrine soliton characteristics. Experimental results are in good agreement with simulations.

HIGH RESOLUTION STIMULATED RAMAN SPECTROSCOPY WITH A 3 MHz ACCURACY WAVEMETER

1987

UV–Vis, IR, Raman and theoretical characterization of a novel quinoid oligothiophene molecular material

2003

A quinoid-type oligothiophene, 3 0 ,4 0 -dibutyl-5,5 00 -bis(dicyanomethylene)-5,5 00 -dihidro-2,2 0 :5 0 ,2 00 -terthiophene, which can be viewed as an analog of TCNQ, has been investigated by spectroelectrochemistry and density functional theory calculations, in its neutral and dianionic states. Electrochemical data show that the molecule can be both reduced and oxidized at relatively low potentials. Upon reduction, both experiments and theory agree well with the generation of a dianionic charged species. The model shows that the electronic structure of the dianion is consistent with two anionic dicyanomethylene groups attached to a central terthienyl spine having an aromatic structure. T…

Theoretical description of the Raman spectrum of a vinylene-bridged quaterthiophene oligomer

2003

The Raman spectrum of a quaterthiophene oligomer incorporating a central vinylene spacer has been investigated using density functional theory B3LYP/6-31G** calculations. The spectrum has been fully assigned with the aid of the calculations and in comparison with unsubstituted quaterthiophene. The spectrum preserves most of the vibrational features of linear oligothiophenes. The vibrations of the vinylene spacer are clearly differentiated from those of the rest of the chain. The vinylene spacer increases the conjugation length of the molecule and induces a frequency downshift of < 20 cm 21 for the normal modes associated with the nas(CyC) and ns(CyC) vibrations of the thiophene rings. The m…

Condensation of classical optical waves beyond the cubic nonlinear Schrodinger equation

2012

International audience; A completely classical nonlinear wave is known to exhibit a process of condensation whose thermodynamic properties are analogous to those of the genuine Bose-Einstein condensation. So far this phenomenon of wave condensation has been studied essentially in the framework of the nonlinear Schrodinger (NLS) equation with a pure cubic Kerr nonlinearity. We study wave condensation by considering two representative generalizations of the NLS equation that are relevant to the context of nonlinear optics, the nonlocal nonlinearity and the saturable nonlinearity. For both cases we derive analytical expressions of the condensate fraction in the weakly and the strongly nonlinea…

In situ analysis with portable Raman and ED-XRF spectrometers for the diagnosis of the formation of efflorescence on walls and wall paintings of the …

2014

This work presents the results of field Raman analyses, assisted by a hand-held energy dispersive X-ray fluorescence spectrometer, for the experimental determination of efflorescence from walls and wall paintings of two Pompeian houses, one with many luxurious decorative elements (House of Marcus Lucretius, Regio IX, Insula 3, House 5/24) and a more modest building (Regio IX, Insula 3, House 1-2). Both exposed and protected rooms were measured in different year seasons, spring (May 2010) and summer (September 2011 and 2012) and considering different orientations. Chemical attacks of acid gases (CO2, SO2 and NOx) on the original compounds of the mortars, biominerals formed by the biological …

A combination of portable non-invasive techniques to study on reverse glass paintings at Mistretta museum

2019

Abstract Reverse painting on glass is an old decorative technique used since the Roman time consisting in applying a cold paint layer on the reverse side. The Sicilian Regional Museum of forestry and pastoral traditions in Mistretta (Messina, Italy) houses the largest collection of reverse glass paintings in Italy with a total of 195 artworks. The artworks are attributed to the different Italian geographic area from north to south Italy. A combination of non-invasive analysis by using complementary portable spectroscopic instrumentations (mainly XRF and Raman Spectrometers) was applied on some selection of reverse glass paintings. The goal of the work is the characterization of the nature o…

TiO2/Ag2O immobilized on cellulose paper: A new floating system for enhanced photocatalytic and antibacterial activities

2021

Paper-TiO2-Ag2O floating photocatalysts were produced under mild condition and their photocatalytic activity for the degradation of aromatic amine under sunlight stimulant was investigated. Characterizations by Raman, XRD, XPS, DRS and PL confirmed the presence of TiO2 and Ag2O, and the morphology of the appended TiO2/Ag2O layer was probed by FE-SEM. The photocatalytic activity of the prepared samples was investigated by the degradation of aniline (AN) in water under simulated sun-light illumination and constrained conditions, i.e. non-stirring and non-oxygenation. The presence of Ag2O combined with TiO2 was shown to improve the resistance of paper to bacteria attack, thus increasing the du…

Optical coherence tomography and Raman spectroscopy for ex vivo characterization of canine skin and subcutaneous tumors: preliminary results

2021

Cancer is one of the leading causes of companion animal mortality. Up to 30% of all canine and feline tumors appear on or directly under the skin. To date, only a limited number of studies applied biophotonics techniques for optical characterization and detection of tumors in pets. In this work, we acquired ex vivo optical coherence tomography (OCT) images and Raman spectra of native skin and the most common canine and feline skin and subcutaneous tumors; lipomas, mast cell tumors, and soft tissues sarcomas. Lipomas exhibited the most distinctive tissue morphology (i.e., honeycomb structure) and biochemistry (lipid-related Raman peaks of 1063, 1301, and 1652 cm-1). Moreover, lipomas had sig…

FT-Raman determination of Mepiquat chloride in agrochemical products

2004

Abstract A fast and environmentally friendly procedure has been developed for Fourier transform Raman (FT-Raman) determination of a quaternary ammonium compound, Mepiquat chloride, in pesticide emulsifiable concentrate formulations. The method is based on the measurement of peak area values between 711 and 701 cm −1 corrected using a baseline defined at 620 cm −1 and interpolated in an external calibration of Mepiquat chloride standards dissolved in water. FT-Raman spectra were collected over 1.5 min from samples confined in screw cap standard chromatographic glass vials, at a nominal resolution of 4 cm −1 accumulating 25 scans per spectra and using a laser power of 1000 mW. Five commercial…