We propose a new algorithm for deconvolution of electrospray ionization mass spectra based on direct assignment of charge to the measured signal at each mass-to-charge ratio (m/z). We investigate two heuristics for charge assignment: the entropy-based heuristic is adapted from a deconvolution algorithm by Reinhold and Reinhold;10 the multiplicative-correlation heuristic is adapted from the multiplicative-correlation deconvolution algorithm of Hagen and Monnig.6 The entropy-based heuristic is insensitive to overestimates of z(max), the maximum ion charge. We test the deconvolution algorithm on two single-component samples: the measured spectrum of human beta-endorphin has two prominent and one very weak line whereas myoglobin has a well-developed quasi-gaussian envelope of 17 peaks. In both cases, the deconvolution algorithm gives a clean deconvoluted spectrum with one dominant peak and very few artefacts. The relative heights of the peaks due to the parent molecules in the deconvoluted spectrum of a mixture of two peptides, which are expected to ionize with equal efficiency, give an accurate measure of their relative concentration in the sample.
S I1 Einstein A-coefficientsEinstein A-coefficients for transitions among the 3s23p3 states of SII, calculated with the CIV3 code, are found to be up to -25% different from those of Mendoza and Zeippen. These new results are used to derive the theoretical emission line ratio R = 1(3s23p3 4S;iz-3s23p3 2D:/2)/ I(3s23p3 4S;/2-3s23p3 2D;/z) = I(6717 A)/1(6730A), which is a very useful electron density diagnostic for gaseous nebulae. The present diagnostin are up to 10% larger than those deduced using the A-values of Mendoza and Zeippen, and will lead to electron density estimates up to -50% greater.
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