Portal de Periódicos da CAPES

Metastable ion studies II. Computer assisted interpretation of the shapes of metastable peaks

1976; Elsevier BV; Volume: 19; Issue: 2 Linguagem: Inglês

10.1016/0020-7381(76)80005-8

1873-3034

John Holmes, Alexander D. Osborne, Gwyneth M. Weese,

Isotope Analysis in Ecology

Metastable peak shapes have been computed for the AEI-GEC MS902S mass spectrometer. The effects of instrument parameters, the masses of the precursor (m1) and daughter (m2) ions and the magnitude of the kinetic energy released upon fragmentation have been considered. The results confirm that dish-topped metastable peaks do not arise from single-valued energy releases, but from the release of a range of energies. Preliminary calculations for the distribution of released energies are presented for the fragmentation C3H7+ → C3H5+ + H2. The results show that Th, the energy release calculated from the peak width at the “horns” or upper extremities is close to the minimum energy released. This, in turn, is a minimum value for the reverse activation energy. The depth of dish, D, was also computed for 63 wide-ranging values of single-valued energy release (Ti) and of the mass quotient {(m1−m2)/m2}. Experimental values of D agreed well with those computed using Ti = Th. The significance of this agreement is discussed. A Monte-Carlo method for evaluating metastable peak shapes is also presented.