Search results for "RAMAN"
showing 10 items of 1328 documents
Highly textured boron/nitrogen co-doped TiO2 with honeycomb structure showing enhanced visible-light photoelectrocatalytic activity
2020
International audience; In this work, we report a novel photocatalyst based on boron and nitrogen co-doped TiO2 rutile (1 1 0) honeycomb structures. The photocatalyst has been prepared by simultaneously oxidizing and doping a Ti-foil substrate at 750 degrees C. The unit cell volume and the crystallite size of grown TiO2 films were measured by Rietveld refinement analysis. The co-doping by boron and nitrogen was achieved simultaneously with the oxidation of the titanium, resulting in a rutile (1 1 0) textured TiO2 film. X-ray photoelectron spectroscopy analysis revealed the presence of Ti-O-N and Ti-O-B-N bonds, and the presence of crystal defects in the lattice was detected and displayed by…
Collisional shifting and broadening coefficients for the rovibrational anisotropic S(J) lines of nitrogen studied by inverse Raman spectroscopy
1996
0377-0486; Line shifting and broadening coefficients of the anisotropic S(J) lines (v = 0, J --> v = 1, J + 2) of the nitrogen molecule were measured at room temperature using high-resolution stimulated Raman spectroscopy. A rotational quantum number dependence of the S(J) line shifts was observed. In order to avoid an asymmetry of experimental origin, a suitable theoretical profile was fitted to the experimental lineshapes. This study allows the testing of the theoretical methods for calculating the line broadening coefficients in anisotropic Raman scattering, which have already been used in the analysis of infrared absorption data. The behaviour of the modified sum rule and the RPA (rando…
Metālisko un heterogēno nanodaļiņu iegūšana ar lāzera ablācijas metodi šķidrumā
2017
Metāliskas kodola-apvalka nanodaļiņas ir jauns inovatīvs un perspektīvs materiālu veids. To izmantošanas iespējas ir plašas, ieskaitot pielietojumus triboloģijā un ūdens elektrolīzē. Īpaši prioritārais nanodaļiņu iegūšanas ar lāzera starojuma palīdzību veids ir impulsa lāzera ablācijas metode. Darbā tiek izpētīta metālisko mērķu lāzera ablācija šķidrumos, kā arī apskatīti lāzera ablācijas metodes fizikālie pamati. Šīs metodes priekšrocības ir, ka pastāv iespēja iegūt galaproduktu bez piemaisījumiem un sakārtot iegūtās nanodaļiņas ar elektriskā lauka palīdzību, lai iegūtu noteikto struktūru. Iegūtās metāliskās nanodaļiņas tiek raksturotas ar skenējošas elektronu mikroskopijas, transmisijas 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.
Water Splitting on Multifaceted SrTiO3 Nanocrystals: Calculations of Raman Vibrational Spectrum
2022
The financial support of M-ERA.net SunToChem project is greatly acknowledged by L.L.R. and Y.A.M. This paper is partly based upon COST (European Cooperation in Science and Technology) Action 18234 Short Term Scientific Mission. The support is greatly acknowledged by E.K. and V.K. The Institute of Solid State Physics, University of Latvia (Latvia) as the Centre of Excellence has received funding from the European Union’s Horizon 2020 Frame-work Programme H2020-WIDESPREAD-01-2016-2017-Teaming Phase2 under grant agreement No. 739508, project CAMART2. The computer resources were provided by the Stuttgart Supercomputing Center (HLRS project DEFTD 12939) and Latvian Super Cluster (LASC).
Infrared based saliva screening test for COVID‐19
2021
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in an unprecedented need for diagnostic testing that is critical in controlling the spread of COVID-19. We propose a portable infrared spectrometer with purpose-built transflection accessory for rapid point-of-care detection of COVID-19 markers in saliva. Initially, purified virion particles were characterized with Raman spectroscopy, synchrotron infrared (IR) and AFM-IR. A data set comprising 171 transflection infrared spectra from 29 subjects testing positive for SARS-CoV-2 by RT-qPCR and 28 testing negative, was modeled using Monte Carlo Double Cross Validation with 50 randomized test and model sets. The testing se…
Raman study of crystals
1997
In this work we present a polarized Raman study of single crystals for several values of the concentration made using different scattering geometries. The Raman spectra, composed of broad bands, have been fitted in accordance with a symmetry analysis which allowed us to assign the vibrational modes, and determine their frequencies and damping constants. The results are compatible with an average hexagonal symmetry for the solid solutions with x in the range . In each of the spectra we found two bands at about 590 and , probably associated with the existence of structures in the solid solutions.
Tunable Polarons in Bose-Einstein Condensates
2017
A toolbox for the quantum simulation of polarons in ultracold atoms is presented. Motivated by the impressive experimental advances in the area of ultracold atomic mixtures, we theoretically study the problem of ultracold atomic impurities immersed in a Bose-Einstein condensate mixture (BEC). The coupling between impurity and BEC gives rise to the formation of polarons whose mutual interaction can be effectively tuned using an external laser driving a quasi-resonant Raman transition between the BEC components. Our scheme allows one to change the effective interactions between polarons in different sites from attractive to zero. This is achieved by simply changing the intensity and the frequ…
Spectral and temporal distribution of biomolecules by Dynamic SERS
2014
In this thesis, the definition of SERS as a biosensor has been tested and a new approach developed for. Also, in terms of quantification, it has been shown that SERS can be an efficient tool. Concerning the selectivity, the spectral quality was improved. A low limit of detection associated to the statistical and dynamic approach allows a very good sensitivity (under the nanomolar). This approach also enables a high reproducibility in time of the sensor. Thus, as low as SERS does not well answer to the sensor capabilities in a classical approach, in our case the coupling between a non-functionalized GNPs substrate coupled with a microfluidic chip, all mounted on a confocal microscope for tem…
On the interpretation of the Raman spectra of Maya Blue: a review on the literature data
2011
The Raman spectroscopy of Maya Blue (MB), a nanostructured organic–inorganic hybrid material, has received considerable attention. A re-evaluation of the Raman literature data for indigo dye, genuine MB samples and model specimens obtained by the binding of indigo to phyllosilicate clays, such as palygorskite and sepiolite, using chemometric analysis of normalised spectra is reported. Available data present features in support of the following ideas: (1) dehydroindigo accompanies indigo in MB; (2) different topological isomers, i.e. dye molecules attached to different coordinative sites of the palygorskite framework, are involved in MB; and (3) different procedures were probably used for pr…