Combined deconvolution and curve fitting for quantitative analysis of unresolved spectral bands

Pierce, John A.; Jackson, Richard S.; Every, Kenneth W. Van; Griffiths, Peter R.; Gao, Hongjun

doi:10.1021/ac00204a011

Cited by 76 publications

(40 citation statements)

References 32 publications

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“…An effective approach to resolve the individual peaks of overlapping bands is the least‐squares curve‐fitting techniques, which calculates an optimized model for the spectrum by use of an iterative procedure to minimize the sum of the squares of the differences between the curve‐fitted spectrum and the data. However, one of the main drawbacks of curve fitting is the appearance of artifacts due to the numerical treatment, when the bands become more overlapped, or the number of overlapped bands increases 26. The most important values for input to the curve‐fitting routine are the number of bands and their positions.…”

Section: Resultsmentioning

confidence: 99%

Quantitative IR characterization of urea groups in waterborne polyurethanes

Shi

Zhan

Luo

et al. 2008

J. Polym. Sci. A Polym. Chem.

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The purpose of this study is to propose a correlation between IR spectra and the urea fraction of waterborne polyurethanes (PUs) to investigate the side reaction, that is, isocyanate–water reaction, during polymerization. This method is based on the decomposition of the spectrum in amide I range, that is, 1600–1800 cm−1, where the bands of interest overlap. Several individual bands present in this region were resolved by employing Fourier self‐deconvolution (FSD) and Gaussian curve‐fitting techniques, and the intensity ratio of urethane's CO to urea's CO was determined. To realize some quantitative measurements, a calibration curve was established with some polyurethane‐urea samples, characterized by 1H NMR, which were used as standards. The concentration ratios of urethane groups to urea groups were determined from 1H NMR. A good correlation was evidenced between IR and 1H NMR measurements. Moreover, waterborne PUs were prepared by miniemulsion polymerization of IPDI with diols. From quantitative IR analysis, it was shown that a vinylic monomer, as a solvent of polyaddition, restrained the isocyanate–water reaction, and this side reaction was influenced by the hydrophilicity of the vinylic monomers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2433–2444, 2008

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Section: Resultsmentioning

confidence: 99%

Quantitative IR characterization of urea groups in waterborne polyurethanes

Shi

Zhan

Luo

et al. 2008

J. Polym. Sci. A Polym. Chem.

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“…However, since the exact composition of the coal is not known, the selection of parameters, such as the number, position, and width of the bands, is not straightforward. The application of Fourier self-deconvolution, maximum likelihood restoration, and the calculation of derivative spectra has been shown capable of narrowing bandwidths in order to facilitate the selection of these parameters [11,12]. However, these techniques provide poor results for spectra with highly overlapped bands, baseline errors or high noise levels [11,12] Although coal spectra typically exhibit these shortcomings, some of these approaches have been utilized [9,13].…”

Section: E Ft-ir Spectroscopy Methods For Carboxyl and Phenolic Groumentioning

confidence: 99%

“…The application of Fourier self-deconvolution, maximum likelihood restoration, and the calculation of derivative spectra has been shown capable of narrowing bandwidths in order to facilitate the selection of these parameters [11,12]. However, these techniques provide poor results for spectra with highly overlapped bands, baseline errors or high noise levels [11,12] Although coal spectra typically exhibit these shortcomings, some of these approaches have been utilized [9,13]. As an alternative to the approach mentioned above, Solomon et al [14,15] defined a set of 24 Gaussian bands with fixed positions and widths that could reproduce coal spectra within the experimental error.…”

Section: E Ft-ir Spectroscopy Methods For Carboxyl and Phenolic Groumentioning

confidence: 99%

The dual role of oxygen functions in coal pretreatment and liquefaction: Crosslinking and cleavage reactions

Serio¹,

Kroo²,

Teng³

et al. 1991

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“…[49][50][51][52][53][54][55][56][57][58][59] The combination of deconvolution and curve fitting allows for qualitative as well as quantitative information on complex spectra. [55][56][57][58][59] These recent developments in band analysis techniques have prompted this study of CO adsorbed on Pt/K-LTL. It will be shown that by combined FSD and curve fitting the linear-CO region of the IR spectrum of Pt/K-LTL consists of a larger number of highly overlapped components, which are grouped into a high-and low-frequency region due to the promotion effect of potassium cations.…”

Section: Introductionmentioning

confidence: 99%

Deconvolution and Curve Fitting of IR Spectra for CO Adsorbed on Pt/K-LTL: Potassium Promoter Effect and Adsorption Site Distribution

1996

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Diffuse reflectance infrared (DRIFT) spectra have been obtained for carbon monoxide adsorbed with and without H 2 O on Pt/K-LTL zeolite. The complex spectra of CO linearly adsorbed on highly dispersed Pt have been analyzed by the combination of Fourier self-deconvolution and curve fitting. The linear-CO spectrum is composed of two broad multiplets: a high-frequency band (HFB) at 2100-1980 cm -1 and a low-frequency band (LFB) at 1990-1860 cm -1 . The relative intensities of the HFB and LFB depend on the amount of coadsorbed water in the zeolite pores. The LFB is associated with an ion-dipole interaction between the oxygen atoms of CO species with potassium cations from the zeolite support. The HFB is associated with linear-CO unperturbed by the alkali promoter effect. It is proposed that water preferentially adsorbs on the K + ions, shielding the ion-dipole interaction. The individual components of the complex HFB and LFB are proposed to be due to CO molecules adsorbed on platinum atoms with different coordination numbers. The average coordination number of the Pt atoms in K-LTL, determined in the applied deconvolution and curvefitting program, corresponds well with that obtained by EXAFS, indicating a metal particle size distribution with particles containing between 1 and 13 platinum atoms. By applying the newly developed method, several literature IR CO spectra of Pt/K-LTL with different relative intensities in the HFB region have been analyzed successfully by adjusting the particle size distribution only. In view of the new results showing the prominent effects of particle size distribution and potassium promotion on the IR spectra of adsorbed CO, previously reported conclusions concerning metal-support interactions in PT/K-LTL should be reconsidered when based on infrared spectroscopic data.

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Combined deconvolution and curve fitting for quantitative analysis of unresolved spectral bands

Cited by 76 publications

References 32 publications

Quantitative IR characterization of urea groups in waterborne polyurethanes

Quantitative IR characterization of urea groups in waterborne polyurethanes

The dual role of oxygen functions in coal pretreatment and liquefaction: Crosslinking and cleavage reactions

Deconvolution and Curve Fitting of IR Spectra for CO Adsorbed on Pt/K-LTL: Potassium Promoter Effect and Adsorption Site Distribution

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