Search results for "Raman spectroscopy."

Optimisation algorithms in the case of mineral detection using Raman Analysis

2013

Abstract Raman analysis can be used to analyse the existence of minerals in an ore sample. Especially the interest here is to analyse given ore sample rapidly, to find out what minerals it contains. Rapid analysis would enable more rapid exploration of minerals as analysis could be carried out on-site. For this study, ore samples were collected from two mines in Northern Finland, Kittila and Kevitsa. An optimisation algorithm was constructed to form a linear combination of reference spectra which best represent the measured spectrum from an ore sample. The reference spectra were collected from a public source. It was found that solving for an optimal summation of reference spectra can be a …

Methods for the vibrational spectroscopy analysis of beers

2009

The main possibilities and drawbacks of vibrational spectroscopy techniques, infrared (both in the middle and near infrared ranges) and Raman, for the analysis of beers have been reviewed taking into consideration methods proposed in the scientific literature for the determination of as many as possible compounds and parameters of beers. Details about the procedures available and comments on the future developments in this field have been based on the experience of authors and extended checking of the characteristics of the procedures published till now.

High Resolution Coherent Anti-Stokes Raman Spectroscopy (CARS) Of O 2 And CO 2

1988

With the help of high spectral quality (linewidth , 6 MHz) injection-locked flashlamp-pumped dye lasers, high resolution Coherent Anti-Stokes Raman Spectroscopy (CARS) has been applied to the study of the Q-branches of 0 2 and CO 2 . The Q-branch linewidths of 02 were obtained from the first nine transitions (J 2 = 1 to 17) recorded at pressures from 0.094 to 1 atm at room temperature. A least squares program was employed to fit calculated spectra to experimental spectra by adjusting different parameters. The collisional broadening coefficients we have obtained are consistent with available Raman data. We have also studied the Q-branch of the fundamental v1 band of CO 2 in the Fermi resonan…

Synthesis, Characterization of FexZr1-xO2Solid Solution Nanoparticles and Bulk Powders Prepared Using a Sol-Gel Technique

2015

Electrical Transport and Confocal Raman Studies of Electrochemically Modified Individual Carbon Nanotubes

2003

Erratum to ‘Raman spectroscopy of β-irradiated silica glass’ by B. Boizot, S. Agnello, B. Reynard, R. Boscaino and G. Petite [J. Non-Cryst. Solids 32…

2004

<title>Electrochromism of W-oxide-based films: some theoretical and experimental results</title>

1995

We survey some recent work related to electrochromic W-oxide-based thin films. The electronic structure of cubic (perovskite) WO3 and HWO3 was calculated from first principles. It was found, among other things, that hydroxide formation was energetically favored. Experimental studies were made on films prepared by reactive magnetron sputtering in Ar + O2 with and without CF4 addition and substrate bias. Structural studies by atomic force microscopy, x-ray diffraction, infrared reflectance spectroscopy, and Raman spectroscopy indicated that the electron bombardment associated with a positive substrate bias led to grain growth and partial crystallization while maintaining a high density of W e…

High Resolution Coherent Raman Spectroscopy: Studies of Molecular Structures

1992

One of the main advantages of the non-linear coherent Raman techniques is the high resolution that can be achieved in rovibrational spectroscopy. Typically an instrumental function of the order of several thousandths of a wavenumber is routinely achieved in SRS or CARS experiments. Since the first recording of the stimulated Raman spectrum of 12CH4 in 1978 [1], numerous studies of molecules have been performed [2–8]. We have built a stimulated Raman experiment in Dijon in which particular attention has been paid to the frequency measurement of the Raman lines [9]. We will describe the application of our experiment to a wide variety of molecules over the last few years: linear molecules, sph…

Optical study of gallium and nitrogen polarity layers of GaN grown on sapphire

2003

A confocal Raman spectroscopic study was carried out on either side of an intentionally grown GaN inversion domain boundary between a pair of strips with opposite (Ga- or N-) polarity. It is shown that the Raman spectra on the N-polarity side displays an A1(TO) mode, prohibited by symmetry considerations, meanwhile on Ga-polarity material this peak is absent, indicating a lower density of defects present in this region. The Raman spectra reveal that in the lateral direction, the change in structural quality accross the inversion domain boundary is rather continuous and extends along 4 ± 1 μm. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Effect of thermal annealing on the luminescence of defective ZnO nanoparticles synthesized by pulsed laser ablation in water

2016

This work concerns ZnO nanoparticles (NPs), with sizes of tens of nm, produced by ablation with a pulsed Nd:YAG laser of a Zn plate in H2O. TEM images evidence the formation of nanoparticles with sizes of tens of nm. Moreover, HRTEM images and Raman spectra show that the distance between the crystalline planes and the vibrational modes are consistent with ZnO nanocrystal in wurtzite structure. Their optical properties are characterized by two emission bands both excited above the energy gap (3.4 eV): the first at 3.3 eV is associated with excitons recombination, the second at 2.2 eV is proposed to originate from a singly ionized oxygen vacancy. The green emission is independent of water pH,…