Spectral deconvolution

Natural minerals may contain simultaneously up to 20-25 luminescence centers, which are characterized by strongly different emission intensities. Usually one or two centers dominate, while others are not detectable by steady-state spectroscopy. In certain cases deconvolution of the liuninescence spectra may be useful, especially in the case of broad emission bands. It was demonstrated that for deconvolution of luminescence bands into individual components, spectra have to be plotted as a function of energy. This conversion needs the transposition of the y-axis by a factor A /hc (Townsend and Rawlands 2000). The intensity is then expressed in arbitrary imits. Deconvolution is made with a least squares fitting algorithm that minimizes the difference between the experimental spectrum and the sum of the Gaussian curves. Based on the presumed band numbers and wavelengths, iterative calculations give the band positions that correspond to the best fit between the spectrum and the sum of calculated bands. The usual procedure is to start with one or 

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S.C. Rutan and S.D. Brown, Pulsed photoacoustic spectroscopy and spectral deconvolution with the Kalman filter for determination of metal complexation parameters. Anal. Chem., 55 (1983) 1707-1710. 

Association Fran aise de Normalisation French Association for Standardisation (Paris, France) Automated Mass Spectral Deconvolution and Identification System (NIST)... 

The central engine of this data workflow is the process of spectral deconvolution. During spectral deconvolution, sets of multiply charged ions associated with particular proteins are reduced to a simplified spectrum representing the neutral mass forms of those proteins. Our laboratory makes use of a maximum entropy-based approach to spectral deconvolution (Ferrige et al., 1992a and b) that attempts to identify the most likely distribution of neutral masses that accounts for all data within the m/z mass spectrum. With this approach, quantitative peak intensity information is retained from the source spectrum, and meaningful intensity differences can be obtained by comparison of LC/MS runs acquired and processed under similar conditions. 

Caarls W, Celej MS, Demchenko AP, Jovin TM (2009) Characterization of coupled ground state and excited state equilibria by fluorescence spectral deconvolution. J Fluorescence 20 181-190... 

DAGAN, S., Comparison of gas chromatography-pulsed flame photometric detection-mass spectrometry, automated mass spectral deconvolution and identification system and gas chromatography-tandem mass spectrometry as tools for trace level detection and identification, J. Chromatogr., A., 2000,868,229-247. 

The Lunar Prospector orbiter carried a gamma-ray/neutron spectrometer (GRS) that made precise measurements of the concentration and distribution of thorium (Lawrence et al., 1998) and hydrogen (Feldman et al., 2001). Subsequent spectral deconvolutions (Prettyman et al., 2006) have produced analyses of iron, titanium, potassium, magnesium, aluminum, calcium, and silicon. The principles of these analytical techniques are explained in Box 13.1. 

Peak purity is based on the proprietary spectral contrast algorithm, which converts spectral data into vectors that are used to compare spectra mathematically. This comparison is expressed as a purity angle that is compared to the purity threshold. Spectral deconvolution techniques are used when two peaks coelute. 

Kende, A., Z. Csizmazia, T. Rikker, et al. 2006. Combination of stir bar sorptive extraction—retention time locked gas chromatography-mass spectrometry and automated mass spectral deconvolution for pesticide identification in fruits and vegetables. Microchem. J. 84 63-69. 

Extensive technical measures have been implemented to allow the ISP to protect confidential, commercial, or sensible military information during on-site analysis. These measures include in particular the option of blinding the GC/MS operating software and security level filters of AMDIS (Automated Mass Spectral Deconvolution and Identification System), the GC/MS raw data processing software. These measures can be applied separately or combined, offering the ISP the choice of a gradual restriction of the information revealed to the IT (for details see Chapter 2). 

Therefore, the information obtained, through onsite GC/MS analysis about the identity of compounds present in a sample should be restricted to chemicals relevant to the aim of the inspection. This is achieved by operating the instrument in a specially developed blinded mode, which shows neither the chromatogram nor mass spectra during or after the chromatographic run. Additionally, if the analysis is conducted in blinded mode, the only available postprocessing software is a specifically developed on-site version of AMDIS (Automated Mass Spectral Deconvolution and Identification System). This software works only with the OCAD, which contains only compounds relevant to the CWC thus, it reports exclusively the presence of compounds for which spectra are in this database library. 

AMDIS Automated Mass Spectral Deconvolution and Identification System... 

Figure 15 Spectral deconvolution of the 1064 cnT1 feature for samples with mTHF = 0.096 (A) and 2.76 U-gTHF/cm2 (B), shown in curves a and f in Figure 12B, respectively. (From Ref. 10.)...

Although the use of evolutionary computing within science is still in its early stages, scientific applications are already notable for their diversity. Evolutionary methods have been used to optimise the geometry of molecules, the shape of propellers, the properties of polymers and the order in which chemicals are produced in industrial flow fines. They have been used in the study of oil extraction, the natural degradation of toxic chemicals in the environment, spectral deconvolution, the interpretation of microwave spectra and in a wide range of other areas. The chapters that follow provide further illustration of the potential of these intriguing and versatile techniques. 

Figure 8 The absorption and MCD spectra of the phthalocyanine-ring-reduced radical anion species [MgPc(—3)] prepared electrochemically at room temperature and recorded at room and cryogenic temperatures (a). (Reproduced with permission from J. Mack, Ph.D. Thesis, University of Western Ontario 1994.) Spectral deconvolution analyses of the absorption and MCD spectra of ZnTPTANP recorded in CH2CI2 (b). (Reproduced with permission from J. Mack, Y. Asano, N. Kobayashi, M. J. Stillman (2005), J. Am. Chem. Soc. 127 17697 -17711. 2005 American Chemical Society)...

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