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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 6 (1992), S. 187-191 
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: An excimer pumped dye laser generating ultra-short (560 fs full width at half maximum, FWHM) pulses in the ultraviolet (UV, 248 nm) and visible (496 nm) spectral ranges is used to desorb protein ions from different matrices. The effects of laser-light energy and power density on secondary-ion yields from insulin are reported. These data are compared to data obtained by employing a nitrogen laser (337 nm, 3 ns FWHM). The existence of a threshold energy density for the matrix-asisted laser desorbtion (MALD) of insulin ions by the ultra-short pulses is established. This threshold energy is of the same order of magnitude for the two laser systems employed and does not depend on the laser pulse length (the energy deposition time). Thus we demonstrate that the amount of laser energy deposited into the sample, rather than the laser power, is the important parameter in the MALD process.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1976), S. 148-153 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The fragmentation patterns and major metastable ions of the mass spectra of the neopentyl-phosphorus derivatives [(CH3)3CCH2]3P, [(CH3)3CCH2]2P(O)H, [(CH3)3CCH2]nPX3-n (n = 1 and 2; X = H, Cl, C6H5 and CH = CH2), [(CH3)3CCH2]3PS, [(CH3)3CCH2]nP(S)R3-n (n = 1 and 2; R = C6H5 and CH = CH2), [(CH3)3 CCH2]2PCH2CH2P[CH2C(CH3)3]2, ([CH3)3CCH2]2PCH2PCH2-CH2P(H)C6H5 and [(CH3)3CCH2]2PCH2CH2P(S)(CH3)2 are described. Fragmentation of a neopentyl group by elimination of either C4H8 or CH3 is very favourable when the neopentyl group is bonded to either a tricoordinate or tetracoordinate phosphorus atom. In neopentylphosphines with two or three neopentyl groups, stepwise elimination of C4H8 from all of the neopentyl groups occurs very readily. The resulting [(CH3)nPX]+.3-n ions are often the most intense ions in the mass spectra.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 25 (1987), S. 1019-1021 
    ISSN: 0749-1581
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Metal(loid) NMR data are reported for a series of 1,1-bis(trimethylmetal)alk-1-enes of the type RR′C=C(MMe3)(M′Me3) (M = Si, Ge, Sn, Pb; M′ = Sn, Pb). These data are commented upon briefly, with particular respect to the two-bond metal-metal coupling constant.Two-bond coupling constants, heavier elements.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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