Methods and methodology for FTIR spectral correction of channel spectra and uncertainty, applied to ferrocene

Islam, Mohammad Tauhidul; Trevorah, Ryan M.; Appadoo, Dominique; Best, Stephen P.; Chantler, Christopher T.

doi:10.1016/j.saa.2017.01.036

Cited by 8 publications

(4 citation statements)

References 19 publications

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“…In Figure 11 a (wavenumber ranged from 400 to 600 cm −1 ), the FTIR spectra displayed transmission bands at 432 and 455–469 cm −1 , which corresponded to the Fe-O bonding from the metal catalyst [ 45 , 46 ]. The samples exhibited metal cation lattice modes at 407 cm −1 [ 47 ], magnetite structure at 483 cm −1 [ 48 ] and ferrocene structure at 494 cm −1 [ 49 ]. Additionally, the sulfur component from the precursor (waste glove) contributed to the transmission band at 413 and 438 cm −1 , with respect to S-S stretching and SO 4 2- [ 45 , 50 ].…”

Section: Resultsmentioning

confidence: 99%

Waste NR Latex Based-Precursors as Carbon Source for CNTs Eco-Fabrications

et al. 2021

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In this work, the potential of utilizing a waste latex-based precursor (i.e., natural rubber glove (NRG)) as a carbon source for carbon nanotube (CNT) fabrication via chemical vapor deposition has been demonstrated. Gas chromatography-mass spectroscopy (GC-MS) analysis reveals that the separation of the lightweight hydrocarbon chain from the heavier long chain differs in hydrocarbon contents in the NRG fraction (NRG-L). Both solid NRG (NRG-S) and NRG-L samples contain >63% carbon, <0.6% sulfur and <0.08% nitrogen content, respectively, as per carbon-nitrogen-sulfur (CNS) analysis. Growth of CNTs on the samples was confirmed by Raman spectra, SEM and TEM images, whereby it was shown that NRG-S is better than NRG-L in terms of synthesized CNTs yield percentage with similar quality. The optimum vaporization and reaction temperatures were 350 and 800 °C, respectively, considering the balance of good yield percentage (26.7%) and quality of CNTs (ID/IG = 0.84 ± 0.08, diameter ≈ 122 nm) produced. Thus, utilization of waste NRG as a candidate for carbon feedstock to produce value-added CNTs products could be a significant approach for eco-technology.

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Section: Resultsmentioning

confidence: 99%

Waste NR Latex Based-Precursors as Carbon Source for CNTs Eco-Fabrications

et al. 2021

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“…Recently, a study was conducted on this system by transmission analysis with careful propagation of data information and uncertainty . This system therefore provides an excellent test of fluorescent multipixel data and further demonstrates the merit of using complementary techniques to confirm molecular geometries. , …”

Section: Introductionmentioning

confidence: 96%

“…12 This system therefore provides an excellent test of fluorescent multipixel data and further demonstrates the merit of using complementary techniques to confirm molecular geometries. 13,14 Fluorescence and transmission XAS measurements were simultaneously taken of two closely related organometallics: bis(N-n-propyl-salicylaldiminato) nickel(II), "n-pr", and bis(Ni-propyl-salicylaldiminato) nickel(II), "i-pr", at the Australian National Beamline Facility, Tsukuba, Japan. Next, 15 mM solutions of each complex were prepared using 60% butyronitrile + 40% acetonitrile as the solvent to avoid microcrystallization at cryostat temperatures, ca.…”

Section: ■ Introductionmentioning

confidence: 99%

New Features Observed in Self-Absorption-Corrected X-ray Fluorescence Spectra for Ni Complexes with Uncertainties

2020

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We present a new technology for analyzing the molecular structure and in particular subtle conformational differences in Ni complexes using X-ray absorption spectroscopy (XAS), enabling tighter and more robust constraints of structure and dynamic bond lengths. Self-absorption and attenuating effects have a large impact in fluorescence X-ray absorption spectroscopy (XAS), compromising accuracy and insight in structural and advanced analyses. We correct for these dominant systematic effects. We investigate nickel(II) complexes, that is, bis(N-n-propyl-salicylaldiminato) nickel(II), “n-pr”, and bis(N-i-propyl-salicylaldiminato) nickel(II), “i-pr”, in 15 mM solutions with 0.1% w/w Ni. One is “square-planar” and one is “tetrahedral”, with identical coordination numbers. We identify two key sources of uncertainty and provide robust estimates for them, reflecting the quality of the data, and provide meaningful estimates of χ r 2 suitable for hypothesis testing. We apply significance and model testing for fluorescence data, with direct uncertainty estimates. Two new peaks are revealed in the X-ray absorption fine structure (XAFS) at k ≈ 4.4 and 5.4 Å–1. The high intrinsic accuracy of our processed data allows these features to be well modeled and yields deeper potential insight. Three important notions in the field are addressed: resolvability of shell radii, estimation of the number of independent data points in least-squares or Bayesian analysis, and the effect of uncertainties on the determined structure and the determinability of key structural parameters. Conventional XAFS fitting requires a k min and a k max. The origin of these limits is explained from the data, in a quantitative manner. Being able to distinguish the isomers spectroscopically and structurally places strong demands on the data, the uncertainties, and the model interpretation, and this article reports success in this subtle structural identification. Two nearby shellsthe innermost two shellsare identified quantitatively, well below the conventional aliasing limit. This illustrates the application of new technology to gain new insight.

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“…This does, however, represent the ideal situation and it can often be the case that other sources of noise are present in the spectrum, e.g., periodic oscillations from interference fringing, and hence subtraction becomes insufficient at generating spectra suitable for quantitative analysis. 35 For other techniques where spectra are measured in finite times, such as in AFM-IR or SFG spectroscopy, there is an unavoidable temporal factor in the measurement. 36,37 Other noise features such as high-frequency periodic oscillations, e.g., from acoustic or electrical interference, can then appear in the spectra and subtraction is no longer appropriate, and smoothing/filtering methods can be much more suitable and effective.…”

Section: Introductionmentioning

confidence: 99%

Spectral Analysis and Deconvolution of the Amide I Band of Proteins Presenting with High-Frequency Noise and Baseline Shifts

2020

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The challenge of deriving quantitative information from the infrared spectra of proteins arises from the large number of secondary structures and amino acid side-chain functional groups that all contribute to the spectral intensity, such as within the amide I band (1600–1700 cm–1). The band is invariably heavily convoluted from overlapping spectral features, thereby making interpretation difficult such that deconvolution is usually required. This work critically examines the methods available to deconvolute the spectra and assesses the commonly used methods and algorithms applied to vibrational spectra for smoothing and peak identification. We show that unless their spectra have very high signal-to-noise ratios, quantitative analysis to decipher protein constituents is not feasible. The advantages and disadvantages of spectral smoothing using adjacent averaging, the Savitzky–Golay filter and the fast Fourier transform filter are examined in detail. The use of derivative spectra to identify peaks is described with particular reference to the influence and reduction of interfering water bands in the amide I region. The reliability of band narrowing techniques such as second-derivative analysis or Fourier deconvolution that lead to the identification of the contributing protein peaks is investigated. Both methods are shown to be limited in their capacity to resolve features with very similar frequencies. Additionally, the presence of narrow bands arising from high-frequency noise whether from atmospheric water vapor, acoustic vibrations, or electrical interference results in both methods becoming increasingly unusable as narrow bands are preferentially enhanced at the expense of broad ones such as the amide I bands. An optimal strategy is critically developed to allow accurate determination and quantification of protein constituents and their conformations. Additionally, quantitative methods are proposed to account for baseline shifts, which would otherwise introduce significant errors in similarity indices.

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Methods and methodology for FTIR spectral correction of channel spectra and uncertainty, applied to ferrocene

Cited by 8 publications

References 19 publications

Waste NR Latex Based-Precursors as Carbon Source for CNTs Eco-Fabrications

Waste NR Latex Based-Precursors as Carbon Source for CNTs Eco-Fabrications

New Features Observed in Self-Absorption-Corrected X-ray Fluorescence Spectra for Ni Complexes with Uncertainties

Spectral Analysis and Deconvolution of the Amide I Band of Proteins Presenting with High-Frequency Noise and Baseline Shifts

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