Accurate intensity calibration of multichannel spectrometers using Raman intensity ratios

The protein (PN), polysaccharide (PS), and extracellular DNA (eDNA) percent concentrations of extracellular polymeric substances (EPS) of biofilm samples harvested from a pilot-scale nitrifying moving bed biofilm reactor (MBBR) were investigated at various operating temperatures and hydraulic retention times (HRTs). Chemically measured EPS PN/PS ratios were shown to correlate to Raman intensity ratios of amide III to carbohydrate at 362 rel. cm−1. The study also demonstrates that tertiary nitrifying MBBR systems may be optimized to operate at HRTs as low as 0.75 to 1.0 h as opposed to conventional HRTs of 2.0 to 6.0 h. The EPS of the nitrifying MBBR biofilm exhibited the lowest percent PN content and the highest percent PSs and eDNA content. In particular, PN/PS ratios lower than 3 were indicative of non-optimal operation of the nitrifying MBBR systems, whereas PN/PS ratios with values significantly below 3 were observed for ammonia underloaded systems at high operating temperatures and hydraulically overloaded systems at low HRTs. This study demonstrates that the PN/PS ratio in EPS is a potential metric to identify non-optimal operation of nitrifying MBBR systems.

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Chromium-Doped Luminescent Glasses for Raman Intensity Calibration with 785 nm Laser Excitation

Microscopy and Microanalysis ◽

10.1017/s1431927600026878 ◽

2001 ◽

Vol 7 (S2) ◽

pp. 160-161

Author(s):

Edgar S. Etz ◽

Wilbur S. Hurst ◽

Steven J. Choquette ◽

Douglas H. Blackburn

Keyword(s):

White Light ◽

Laser Excitation ◽

Broad Band ◽

Emission Spectra ◽

Calibration Procedure ◽

Rare Earth Ions ◽

Excitation Wavelength ◽

Raman Intensity ◽

Instrument Response Function ◽

Intensity Calibration

In work reported previously we, and the McCreery Group at Ohio State University, have proposed the use of glass luminescence standards for the calibration of the Raman spectral intensity. We now have a program underway that is directed at the development of such secondary standards for the calibration of the Raman instrument response function. The first Raman intensity standard to be certified and issued by NIST this year will be for the relative intensity calibration of Raman spectra excited at 785 nm. in general, for any laser excitation wavelength, the calibration procedure is based on the use of luminescent glasses, doped with either transition metal or rare earth ions, that will furnish structureless, broad-band emission spectra upon laser excitation, over any chosen Raman range. For any selected glass standard, the intensity of the luminescence spectrum is calibrated versus the radiant output of a NIST-calibrated white light source, thereby transferring the white light calibration onto the output emission of the luminescent glass.

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Effect of polarization and geometric factors on quantitative laser-induced fluorescence- to-Raman intensity ratios of water samples and a new calibration technique

Journal of the Optical Society of America B ◽

10.1364/josab.20.001980 ◽

2003 ◽

Vol 20 (9) ◽

pp. 1980 ◽

Cited By ~ 8

Author(s):

Vasanthi Sivaprakasam ◽

Dennis K. Killinger

Keyword(s):

Water Samples ◽

Laser Induced Fluorescence ◽

Raman Intensity ◽

Calibration Technique ◽

Geometric Factors ◽

Intensity Ratios

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Development and Certification of NIST Standard Reference Materials for Relative Raman Intensity Calibration

Microchimica Acta ◽

10.1007/s00604-004-0315-2 ◽

2005 ◽

Vol 149 (3-4) ◽

pp. 175-184 ◽

Cited By ~ 13

Author(s):

Edgar S. Etz ◽

Steven J. Choquette ◽

Wilbur S. Hurst

Keyword(s):

Reference Materials ◽

Standard Reference Materials ◽

Raman Intensity ◽

Intensity Calibration

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Detection and quantitation of cellulose II by Raman spectroscopy

10.21203/rs.3.rs-661415/v1 ◽

2021 ◽

Author(s):

Umesh P. Agarwal ◽

Sally A. Ralph ◽

Carlos Baez ◽

Richard S. Reiner

Keyword(s):

Raman Spectroscopy ◽

Crystalline Cellulose ◽

Cellulose Ii ◽

Raman Intensity ◽

Cellulose I ◽

X Ray ◽

Pure Cellulose ◽

Natural Cellulose ◽

Intensity Ratios ◽

Cellulose Materials

Abstract In cellulose materials, the cellulose II polymorph is often present either exclusively or inconjunction with cellulose I, the natural cellulose. Moreover, in regenerated andmercerized fibers (e,g., viscose and lyocell), natural cellulose adopts to the crystalstructure cellulose II Therefore, its detection and quantitation are important for acomplete assessment of such materials investigations. In the Raman spectra of suchmaterials, a band at 577 cm -1 is typically observed indicating the presence of thispolymorph. In the present study, to quantify the content of cellulose II, a calibrationmethod was developed based on the intensity of the 577 cm -1 peak relative to the1096 cm -1 band of cellulose. For this purpose, in addition to pure cellulose I andcellulose II samples (respectively, Avicel PH-101 and mercerized Avicel PH-101; hencereferred to as Avicel I and Avicel II), a set of five samples were produced by mixingthem in known quantities of Avicel I and Avicel II. The crystalline cellulose II contents ofthe samples were calculated based on the X-ray crystallinity of mercerized Avicel I.These seven samples were included in the calibration set and their Raman spectrawere obtained. Subsequently, Raman intensity ratios I 577 /I 1096 were calculatedby taking ratios of peak intensities at 577 and 1096 cm -1 . These ratios were plottedagainst the % of crystalline cellulose II present in the calibration set samples and thetwo were found to be linearly correlated (R 2 = 0.9944). The set-samples were alsoanalyzed using XRD which were then compared with the Raman method developedhere. Compared to XRD, the Raman method was found to be more sensitive atdetecting and quantifying cellulose II. Additionally, several cellulose II containingmaterials were analyzed by the new Raman method.

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Filling rate dependence on theoretical Raman spectra of carbon C60 peapods

OAJ Materials and Devices ◽

10.23647/ca.md20161221 ◽

2016 ◽

Vol vol1 (1) ◽

Author(s):

Hassane Chadli ◽

A. Rahmani ◽

A. Ait Abdelkader ◽

F. Fergani ◽

B. Fakrach

Keyword(s):

Raman Spectra ◽

Single Wall Carbon Nanotubes ◽

Raman Intensity ◽

Filling Rate ◽

Spectral Moments ◽

Moments Method ◽

Polarization Theory ◽

Intensity Ratios ◽

Bond Polarization ◽

Good Agreement

We use the spectral moments method in the framework of the bond-polarization theory to calculate nonresonant Raman spectra of C60 peapods as a function of the concentration of fullerenes inside the single wall carbon nanotubes. The evolution of the average Raman intensity ratios between Raman mode of C60 molecules and nanotube as a function of the concentration of fullerenes has been analyzed and a general good agreement is found between calculations and measurements. #CARBON_NANOTUBES #PEAPODS #RAMAN_SPECTROSCOPY #SIMULATION #SPECTRAL_MOMENT_METHOD

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Influence of X-Ray Induced Fluorescence on Energy Dispersive X-Ray Analysis of Thin Foils

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100079164 ◽

1977 ◽

Vol 35 ◽

pp. 328-329

Author(s):

E. A. Kenik ◽

J. Bentley

Keyword(s):

Thin Foil ◽

Electron Excitation ◽

Simple Approach ◽

Foil Thickness ◽

X Rays ◽

X Ray ◽

Hole Spectrum ◽

Illumination System ◽

Thin Foils ◽

Intensity Ratios

Cliff and Lorimer (1) have proposed a simple approach to thin foil x-ray analy sis based on the ratio of x-ray peak intensities. However, there are several experimental pitfalls which must be recognized in obtaining the desired x-ray intensities. Undesirable x-ray induced fluorescence of the specimen can result from various mechanisms and leads to x-ray intensities not characteristic of electron excitation and further results in incorrect intensity ratios.In measuring the x-ray intensity ratio for NiAl as a function of foil thickness, Zaluzec and Fraser (2) found the ratio was not constant for thicknesses where absorption could be neglected. They demonstrated that this effect originated from x-ray induced fluorescence by blocking the beam with lead foil. The primary x-rays arise in the illumination system and result in varying intensity ratios and a finite x-ray spectrum even when the specimen is not intercepting the electron beam, an ‘in-hole’ spectrum. We have developed a second technique for detecting x-ray induced fluorescence based on the magnitude of the ‘in-hole’ spectrum with different filament emission currents and condenser apertures.

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Valence state analysis of elements by EPMA and its application

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100134752 ◽

1990 ◽

Vol 48 (2) ◽

pp. 230-231

Author(s):

Chen Liqing ◽

Liu Zuqin ◽

Zhang Wei

Keyword(s):

Valence State ◽

Line Intensities ◽

Valence States ◽

Valence Electrons ◽

Fe And Mn ◽

Intensity Ratios ◽

State Analysis

Valence state analyses of Fe and Mn in oxides by EPMA have been reported in literature. In this paper, the effects of valence state on intensity ratios ILα/IKα and ILα/ILβ of Cu, Ni, Co, Fe, Mn, Cr and their oxides, and on intensity ratios ILβ2/ILα1 and ILγ1/ILα1 of Mo, Nb, Zr and their oxides were studied. It was observed that intensity ratios change with valence states in accordance with some regularities, and these effects could be utilized for analyzing the valence states of catalysts.Valence state analysis of elements by EPMA is based on the fact that changes in the states of valence electrons in the outer shells of an atom cause corresponding changes in line intensities. The M electrons of Cu, Ni, Co, Fe, Mn, Cr and the N electrons of Mo, Nb, Zr are valence electrons. Line Kα1,2 and six lines of L are produced from the transitions of K-L2,3 and L-M or L-N respectively.

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