Raman Spectroscopy of Redox Activity in Cathodically Electrodeposited Nickel Hexacyanoferrate Thin Films

2002 ◽  
Vol 56 (8) ◽  
pp. 1021-1029 ◽  
Author(s):  
William A. Steen ◽  
Kavita M. Jeerage ◽  
Daniel T. Schwartz
Keyword(s):  
Thin Films ◽  
Raman Spectroscopy ◽  
Raman Spectra ◽  
Oxidation State ◽  
Principal Component ◽  
Redox Activity ◽  
Nickel Hexacyanoferrate ◽  
The Matrix ◽  
Electrodeposited Nickel ◽  
Spectral Variance

The intercalation of cations into electrodeposited nickel hexacyanoferrate (NiHCF) depends on the stoichiometry and oxidation state of the material. To better understand this material's performance as a cation separation matrix, the oxidation state needs to be measured independently from the stoichiometry, regardless of the particular intercalated cation. Reported is the use of Raman spectroscopy to quantify the absolute oxidation state of NiHCF thin films. Raman spectroscopy probes NiHCF's cyanide bonds, which are sensitive to the oxidation state of the matrix. The oxidation state is controlled via potentiostatic experiments in electrolytes containing Na+, K+, and Cs+ (NO3− is the common anion). Principal component analysis (PCA) on the Raman spectra shows that more than 90% of the spectral variance is captured by one principal component, with a score value shown to be directly related to the oxidation state of the film. A universal, predictive regression model was developed using these score values as the dependent variables and Raman spectra as the independent variables. The results were confirmed with electrochemistry and energy dispersive X-ray spectroscopy.

Laser Induced Oxidation Effects in Bismuth Thin Films

2012 ◽  
Vol 1477 ◽  
Author(s):  
Marco A. Zepeda ◽  
Michel Picquart ◽  
Emmanuel Haro-Poniatowski
Keyword(s):  
Thin Films ◽  
Raman Spectroscopy ◽  
Laser Irradiation ◽  
Raman Spectra ◽  
Exposure Time ◽  
Oxidation Process ◽  
Energy Dispersion Spectroscopy ◽  
Irradiation Power ◽  
Pure Bismuth ◽  
532 Nm

ABSTRACTThe Laser induced oxidation process of bismuth was investigated using Raman spectroscopy. Upon laser irradiation (λ = 532 nm) pure Bismuth was transformed gradually into Bi2O3. Raman spectra of the samples showed the characteristics peaks for pure Bi located at 71 cm-1 and 96 cm-1. The oxidation process was monitored by Raman spectra with four additional bands located at about 127 cm-1, 241 cm-1, 313 cm-1 and 455 cm-1. Maintaining constant the exposure time of irradiation, the intensity of these bands depended on laser irradiation power. The presence of Bi2O3 in the sample was confirmed through by energy dispersion spectroscopy (EDS).

Heating Effects of Desi Ghee Using Raman Spectroscopy

2018 ◽  
Vol 72 (6) ◽  
pp. 833-846 ◽  
Author(s):  
Naveed Ahmad ◽  
Muhammad Saleem ◽  
Mushtaq Ahmed ◽  
Shaukat Mahmood
Keyword(s):  
Principal Component Analysis ◽  
Raman Spectroscopy ◽  
Raman Spectra ◽  
Principal Component ◽  
Nondestructive Technique ◽  
Molecular Changes ◽  
Spectral Bands ◽  
Heating Effects ◽  
Excitation Laser ◽  
First Time

Raman spectroscopy as a fast and nondestructive technique has been used to investigate heating effects on Desi ghee during frying/cooking of food for the first time. A temperature in the range of 140–180℃ has been investigated within which Desi ghee can be used safely for cooking/frying without much alteration of its natural molecular composition. In addition, heating effects in case of reuse, heating for different times, and cooking inside pressure cookers are also presented. An excitation laser at 785 nm has been used to obtain Raman spectra and the range of 540–1800 cm−1 is found to contain prominent spectral bands. Prominent variations have been observed in the Raman bands of 560–770 cm−1, 790–1160 cm−1, and 1180–1285 cm−1 with the rise in temperature. The spectral variations have been verified using classifier principal component analysis. It has been found that Desi ghee can be reused if heated below 180℃ and it can be heated up to 30 min without any appreciable molecular changes if a controlled heating can be managed.

scholarly journals A Noninvasive Accurate Measurement of Blood Glucose Levels with Raman Spectroscopy of Blood in Microvessels

Molecules ◽  
2019 ◽  
Vol 24 (8) ◽  
pp. 1500 ◽  
Author(s):  
Nan Li ◽  
Hang Zang ◽  
Huimin Sun ◽  
Xianzhi Jiao ◽  
Kangkang Wang ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Blood Glucose ◽  
Raman Spectra ◽  
Interstitial Fluid ◽  
Time Lag ◽  
Back Propagation ◽  
Principal Component ◽  
Oral Glucose ◽  
Multiple Characteristic ◽  
Non Invasive

Raman spectra of human skin obtained by laser excitation have been used to non-invasively detect blood glucose. In previous reports, however, Raman spectra thus obtained were mainly derived from the epidermis and interstitial fluid as a result of the shallow penetration depth of lasers in skin. The physiological process by which glucose in microvessels penetrates into the interstitial fluid introduces a time delay, which inevitably introduces errors in transcutaneous measurements of blood glucose. We focused the laser directly on the microvessels in the superficial layer of the human nailfold, and acquired Raman spectra with multiple characteristic peaks of blood, which indicated that the spectra obtained predominantly originated from blood. Incorporating a multivariate approach combining principal component analysis (PCA) and back propagation artificial neural network (BP-ANN), we performed noninvasive blood glucose measurements on 12 randomly selected volunteers, respectively. The mean prediction performance of the 12 volunteers was obtained as an RMSEP of 0.45 mmol/L and R2 of 0.95. It was no time lag between the predicted blood glucose and the actual blood glucose in the oral glucose tolerance test (OGTT). We also applied the procedure to data from all 12 volunteers regarded as one set, and the total predicted performance was obtained with an RMSEP of 0.27 mmol/L and an R2 of 0.98, which is better than that of the individual model for each volunteer. This suggested that anatomical differences between volunteer fingernails do not reduce the prediction accuracy and 100% of the predicted glucose concentrations fall within Region A and B of the Clarke error grid, allowing acceptable predictions in a clinically relevant range. The Raman spectroscopy detection of blood glucose from microvessels is of great significance of non-invasive blood glucose detection of Raman spectroscopy. This innovative method may also facilitate non-invasive detection of other blood components.

scholarly journals Raman Spectroscopy in Colorectal Cancer Diagnostics: Comparison of PCA-LDA and PLS-DA Models

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Wenjing Liu ◽  
Zhaotian Sun ◽  
Jinyu Chen ◽  
Chuanbo Jing
Keyword(s):  
Colorectal Cancer ◽  
Raman Spectroscopy ◽  
Discriminant Analysis ◽  
Diagnostic Accuracy ◽  
Raman Spectra ◽  
Principal Component ◽  
Cancer Diagnostics ◽  
Analysis Model ◽  
Tissue Samples ◽  
Linear Discriminant

Raman spectra of human colorectal tissue samples were employed to diagnose colorectal cancer. High-quality Raman spectra were acquired from normal and cancerous colorectal tissues from 81 patients. Subtle Raman variations, such as for peaks at 1134 cm−1 (protein, C-C/C-N stretching) and 1297 cm−1 (lipid, C-H2 twisting), were observed between normal and cancerous colorectal tissues. The average peak intensity at 1134 and 1297 cm−1 was increased from approximately 235 and 72 in the normal group, respectively, to 315 and 273 in the cancer group. The variations of Raman spectra reflected the changes of cell molecules during canceration. The multivariate statistical methods of principal component analysis-linear discriminant analysis (PCA-LDA) and partial least-squares-discriminant analysis (PLS-DA), together with leave-one-patient-out cross-validation, were employed to build the discrimination model. PCA-LDA was used to evaluate the capability of this approach for classifying colorectal cancer, resulting in a diagnostic accuracy of 79.2%. Further PLS-DA modeling yielded a diagnostic accuracy of 84.3% for colorectal cancer detection. Thus, the PLS-DA model is preferable between the two to discriminate cancerous from normal tissues. Our results demonstrate that Raman spectroscopy can be used with an optimized multivariate data analysis model as a sensitive diagnostic alternative to identify pathological changes in the colon at the molecular level.

Nanoindentation-Induced Phase Transformation in Silicon Thin Films

2013 ◽  
Vol 586 ◽  
pp. 112-115 ◽  
Author(s):  
Radim Ctvrtlik ◽  
Jan Tomastik ◽  
Vaclav Ranc
Keyword(s):  
Thin Films ◽  
Raman Spectroscopy ◽  
High Pressure ◽  
Phase Transformation ◽  
Raman Spectra ◽  
Structural Changes ◽  
Berkovich Indenter ◽  
Silicon Thin Films ◽  
Free Silicon ◽  
Amorphous Si

Nanoindentation-induced phase transformation of amorphous, annealed amorphous and microcrystalline hydrogen-free silicon thin films were studied. Series of nanoindentation experiments were performed with a sharp Berkovich indenter at various unloading rates. The structural changes in indentation deformed regions were examined using Raman spectroscopy. Analyses of indentation curves and Raman spectra suggest that high pressure phases appear more easily in annealed amorphous Si thin films than in microcrystalline ones.

scholarly journals Комбинационное рассеяние света в эвтектическом композите InSb-MnSb

2020 ◽  
Vol 54 (4) ◽  
pp. 341
Author(s):  
И.Х. Мамедов ◽  
Д.Г. Араслы ◽  
Р.Н. Рагимов ◽  
А.А. Халилова
Keyword(s):  
Thin Films ◽  
Frequency Shift ◽  
Raman Spectra ◽  
High Frequency ◽  
Theoretical Data ◽  
Eutectic Composite ◽  
Flash Evaporation ◽  
Evaporation Method ◽  
The Matrix ◽  
High Frequency Shift

Raman spectra of bulk samples of the InSb-MnSb eutectic composite and their thin films prepared by the flash evaporation method have been studied. In the Raman spectra observed TO and LO modes at frequencies of 179.5 cm-1 and 192.4 cm-1 correspond to InSb compound and also the peaks at frequencies 122 cm-1, 127 cm-1, 167 cm-1, 211 cm-1, 245.5 cm-1 correspond to theoretical data for MnSb as is well known from literature. The TO mode in the Raman spectra for films is shifted toward lower energies (178 cm-1), but the LO mode is higher (196 cm-1). The high-frequency shift of the LO mode in the composite with compared its value for InSb is probably due to the presence of deformation at the matrix-inclusion interface, as well as the contribution by surface phonons scattering.

Microchip Lasers as a Compact Excitation Source for Raman Spectroscopy

2000 ◽  
Vol 54 (5) ◽  
pp. 739-741 ◽  
Author(s):  
Alfons Schulte ◽  
Chris Fredricksen ◽  
Scott Buchter ◽  
Greg Mizell
Keyword(s):  
Thin Films ◽  
Raman Spectroscopy ◽  
Solid State ◽  
Raman Spectra ◽  
Solid State Laser ◽  
Microchip Laser ◽  
Laser Source ◽  
Spectral Measurements ◽  
Microchip Lasers ◽  
Raman Spectral

The application of a new microchip laser source for Raman spectral measurements is demonstrated. The performance of the device is evaluated and illustrated by Raman spectra of diamond thin films and a solid-state laser host material.

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