Ion kinetic energy spectrometry allows the study of both unimolecular and bimolecular reactions and is a unique source of information on thermochemistry, molecular structure, isotopic quantitation, and reaction dynamics

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The 70eV electron ionization mass spectra of polycyclic aromatic compounds are characterized by the presence of relatively stable multiply charged molecular iolls m]"+ (n=24). When generated from the compounds benzene, napthalene, anthracene, phenanthrene, 2,3-benzanthracene, 1,2-benzanthracene, chrysene, 9,lO-benzopbenanthrene and pyrene, the relative abundances of the multiply charged ions increase dramatically with the number of Mgs. These compounds form multiply charged molecular ions

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Various methods of scanning the electric and the magnetic sectors of a double focusing mass spectrometer are critically discussed and assessed.In double focusing mass spectrometers having separate electric and magnetic sectors it is possible to scan in various ways so as to observe the products of decompositions of metastable ions without interference from the stable ions that make up the normal mass spectrum.' It is the purpose of the present paper to consider all those ways that involve scanning so as to observe the products of fragmentations in the socalled first field free region, the region immediately following the accelerating region. All these scanning possibilities are independent of the order in which the electric ;and magnetic sectors are traversed by the product [m2]+ ions. The only scans that do depend on the field order are those designed to study fragmentations occurring in the second field free region, between the two sectors. Some of these special scans that lead to useful spectra are also discussed. Table 1 below, where the way in which V, E and B must be changed to transmit the product ions is shown corresponding to several different values of x. Interesting possibilities arise for the cases x = 0 and x = 1. In both cases a simple scan gives a spectrum of all the various precursor ions of any mass ml that give rise to the selected product ions [m2]+.

An important specific rearrangement process in oxygenated organic compounds has been found to involve the formation of carbon monoxide. A combination of accurate mass measurement and metastable peak analysis has provided in many cases unequivocal information on the course of the fragmentation processes involved. A fairly detailed study of the fragmentation of anthraquinone has shown that fresh bonds are formed to produce the ionized forms of fluorenone and o-diphenylene; in the case of hydroxy derivatives of anthraquinone the ion CnH,+ appears to have high stability. Other compounds, mainly aromatic ethers and ketones, are discussed in a similar way and in a few cases suggestions are made regarding the nature of the transition states involved in these s ecific rearrangements. Analogously, HCN, NO and other groups are eliminated from nitrogen-containing compounds suct as the nitroanilines. The theoretical implications of such specific low energy processes are considered briefly, with reference to the quasi-equilibrium theory of mass spectra.