The internal energy of product ions formed in mass spectral reactions

Major factors which determine the distribution of internal energy of a primary product ion A + , P ( E ) A+ , at formation are delineated in terms of the quasi‐equilibrium theory and a variety of experimental evidence is offered to support these conclusions. These major factors include: the P ( E ) of the molecular ion, the rate constants as a function of energy, κ( E ), for M + ·→A + + N 0 and for competing reactions of M + ·, and the partitioning of excess internal energy between A + and N 0 . The ‘fluctuation effect’ on this partitioning makes P ( E ) A+ relatively insensitive to many structural and energy changes.