scholarly journals Composition of uranium oxide surface layers analyzed by μ-Raman Spectroscopy

2003 ◽  
Vol 802 ◽  
Author(s):  
Wigbert J. Siekhaus
Keyword(s):  
Raman Spectroscopy ◽  
Fourier Transform ◽  
Uranium Oxide ◽  
Diffuse Reflectance ◽  
High Sensitivity ◽  
Depth Resolution ◽  
Oxide Thickness ◽  
Oxide Surface ◽  
Surface Layers ◽  
The Past

AbstractOxide thickness and composition averaged over a few square millimeter have been measured with nm thickness resolution by diffuse reflectance Fourier transform infrared (FTIR) spectroscopy. μ-Raman spectroscopy has been done on powders and bulk samples in the past, and can now be done on surfaces layers with μm lateral and depth resolution using con-focal microscopy. Here we apply con-focal-microscopy-based μ -Raman spectroscopy to a freshly polished/lightly oxidized and to heavily oxidized uranium to determine its sensitivity. The spectra show that μ-Raman spectroscopy does detect oxide thickness and oxide composition with high sensitivity.

Decomposition Kinetics of EGDN on ZnO by Diffuse Reflectance Infrared Fourier Transform Spectroscopy

1995 ◽  
Vol 49 (4) ◽  
pp. 444-450 ◽  
Author(s):  
D. O. Henderson ◽  
R. Mu ◽  
Y. S. Tung ◽  
G. C. Huston
Keyword(s):  
Fourier Transform ◽  
Diffuse Reflectance ◽  
Fourier Transform Spectroscopy ◽  
Decomposition Kinetics ◽  
Oxide Surface ◽  
Suitable Material ◽  
Langmuir Kinetics ◽  
Ethylene Glycol Dinitrate ◽  
Diffuse Reflectance Infrared ◽  
Kinetics Of

Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was used to follow the decomposition kinetics of ethylene glycol dinitrate (EGDN) adsorbed on a zinc oxide surface at 313 K. The principal decomposition products are most likely a variety of carbonyl, carboxylate, and carbonate species. The appearance of these products follows zeroth-order Langmuir kinetics. Another decomposition product, carbon monoxide, exhibited more complex kinetics. Overall, because of its reactivity with EGDN, ZnO does not appear to be a suitable material for an explosive preconcentrator device.

Some Applications of Fourier Transform Infrared Photoacoustic Spectroscopy

1981 ◽  
Vol 35 (6) ◽  
pp. 549-557 ◽  
Author(s):  
K. Krishnan
Keyword(s):  
Fourier Transform ◽  
Infrared Spectra ◽  
Diffuse Reflectance ◽  
High Sensitivity ◽  
Fourier Transform Infrared ◽  
Chemical Systems ◽  
Infrared Photoacoustic Spectroscopy ◽  
Saturation Effects ◽  
Total Internal Reflectance ◽  
Internal Reflectance

A new photoacoustic cell for use with Fourier transform infrared spectrometers is detailed. Photoacoustic infrared spectra showing high sensitivity on a variety of chemical systems are presented. Comparison of the photoacoustic infrared spectra with transmission and attenuated total internal reflectance spectra show that saturation effects can play a prominent role in the photoacoustic spectra. Spectral subtractions and study of the situ chemical reactions are possible using the photoacoustic technique. The photoacoustic and diffuse reflectance techniques yield very similar spectra.

scholarly journals The growth of epitaxial uranium oxide observed by micro-Raman spectroscopy

2005 ◽  
Vol 893 ◽  
Author(s):  
Niña Caculitan ◽  
Wigbert J. Siekhaus
Keyword(s):  
Raman Spectroscopy ◽  
Optical Properties ◽  
Oxide Layer ◽  
Uranium Oxide ◽  
Signal Amplitude ◽  
Oxide Thickness ◽  
Grain Structure ◽  
Raman Signal ◽  
Oxide Growth ◽  
Micro Raman Spectroscopy

AbstractRaman spectroscopy can be performed with micrometer resolution and can thus be used to determine the dependence of oxide thickness on the substrate’s grain structure or local impurity inclusions. The Raman signal amplitude emitted from an epitaxial uranium oxide layer as a function of oxide thickness has been modeled for light of 632.8 nm wavelength incident on the oxide and reflected from the uranium substrate using the optical properties determined by spectrophotometry. The model shows that the Raman signal increases with oxide thickness and saturates at about 150 nm thickness. The model was compared with the measured Raman signal amplitude of an epitaxial uranium oxide layer growing in air with a known time dependence of oxide growth.

The Use of Ratio-Recording Interferometry for the Measurement of Infrared Emission Spectra: Applications to Oxide Films on Copper Surfaces

1975 ◽  
Vol 29 (6) ◽  
pp. 496-500 ◽  
Author(s):  
D. Kember ◽  
N. Sheppard
Keyword(s):  
Emission Spectra ◽  
Black Body ◽  
Infrared Emission ◽  
Thin Layers ◽  
Oxide Surface ◽  
Surface Layers ◽  
Selective Reflection ◽  
Copper Surfaces ◽  
Emission And Absorption Spectra ◽  
Direct Correspondence

Infrared emission spectra from metal samples with oxide surface layers are shown to be very advantageously studied using the spectrum-ratioing facility of a recording infrared interferometer. The emission from a given sample is ratioed against that from a black-body emitter at the same temperature so as to give emittance as a function of wavenumber directly. This method has very useful application to irregularly shaped metal emitters. In the absence of selective reflection there is a direct correspondence between emission and absorption spectra for thin layers of an emitting substance. However, the presence of selective reflection leads to reduced emission and to considerable differences in the appearance of “absorption” and emission spectra in regions of strong absorption. Emission spectra obtained from copper plates heated, above 150°C, for different periods in air are shown clearly to indicate the presence of cuprous, Cu(I), and cupric, Cu(II), oxides in the surface layer.

scholarly journals Barium Titanium Oxynitride from Ammonia-Free Nitridation of Reduced BaTiO3

Inorganics ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 62
Author(s):  
Hua Guo ◽  
Aleksander Jaworski ◽  
Zheng Chen ◽  
Can Lu ◽  
Adam Slabon ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Nmr Spectroscopy ◽  
Transition Metal ◽  
Signal Intensity ◽  
Diffuse Reflectance ◽  
Conduction Band Edge ◽  
Vacancy Ordering ◽  
Vis Spectroscopy ◽  
O Vacancy ◽  
Barium Titanium

We investigated the nitridation of reduced BaTiO3, BaTiO2.60H0.08, corresponding to an oxyhydride with a large concentration of O defects (>10%). The material is readily nitrided under flowing N2 gas at temperatures between 400 and 450 °C to yield oxynitrides BaTiO2.6Nx (x = 0.2−0.22) with a slightly tetragonally distorted perovskite structure, a ≈ 4.01 and c ≈ 4.02 Å, and Ti partially remaining in the oxidation state III. The tetragonal structure was confirmed from Raman spectroscopy. 14N MAS NMR spectroscopy shows a single resonance at 270 ppm, which is typical for perovskite transition metal oxynitrides. However, largely different signal intensity for materials with very similar N content suggests N/O/vacancy ordering when prolonging nitridation times to hours. Diffuse reflectance UV-VIS spectroscopy shows a reduction of the intrinsic band gap to 2.4–2.45 eV compared to BaTiO3 (~3.2 eV). Mott-Schottky measurements confirm n-type conductivity and reveal a slight negative shift of the conduction band edge from –0.59 V (BaTiO3) to ~–0.65 eV.

scholarly journals An infrared spectral biomarker accurately predicts neurodegenerative disease class in the absence of overt symptoms

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lila Lovergne ◽  
Dhruba Ghosh ◽  
Renaud Schuck ◽  
Aris A. Polyzos ◽  
Andrew D. Chen ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Neurodegenerative Disease ◽  
High Probability ◽  
Behavioral Characteristics ◽  
Brain Pathology ◽  
Disease Class ◽  
The Past ◽  
Infrared Spectral ◽  
New Biomarkers ◽  
Physiological Indicator

AbstractAlthough some neurodegenerative diseases can be identified by behavioral characteristics relatively late in disease progression, we currently lack methods to predict who has developed disease before the onset of symptoms, when onset will occur, or the outcome of therapeutics. New biomarkers are needed. Here we describe spectral phenotyping, a new kind of biomarker that makes disease predictions based on chemical rather than biological endpoints in cells. Spectral phenotyping uses Fourier Transform Infrared (FTIR) spectromicroscopy to produce an absorbance signature as a rapid physiological indicator of disease state. FTIR spectromicroscopy has over the past been used in differential diagnoses of manifest disease. Here, we report that the unique FTIR chemical signature accurately predicts disease class in mouse with high probability in the absence of brain pathology. In human cells, the FTIR biomarker accurately predicts neurodegenerative disease class using fibroblasts as surrogate cells.

Calibration Methods to Circumvent Unknown Component Spectra for Quantitative in situ Raman Monitoring of Co-Polymerisation Reaction

2021 ◽  
Author(s):  
Wendy Rusli ◽  
Pavan Kumar Naraharisetti ◽  
Wee Chew
Keyword(s):  
Raman Spectroscopy ◽  
Reaction Monitoring ◽  
The Past ◽  
In Situ Raman ◽  
Calibration Methods ◽  
Unknown Component

The use of Raman spectroscopy for reaction monitoring has been successfully applied over the past few decades. One complication in such usage is the applicability for quantitative reaction studies. This...

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