Radical cations ionization energetics

More recent work on the chemistry of gaseous 1,3,5-cycloheptatriene radical cations concerns the energetics and dynamics of the interconversion with ionized toluene and the competing losses of H from both isomers. Lifshitz and coworkers22,143 have reported on the details of the energy surface of the ions. Most importantly, the critical energies... 

Once the sample has been introduced into the mass spectrometer, it must be ionized. There are a number of different ionization techniques which span a wide-range of different compound classes. The original ionization technique was termed electron impact (El). El involves the interaction of the compound of interest (M) with 70 eV electrons that have been emitted from a filament wire (1 eV = 1.6 10"19 Joule). This results in a relatively energetic reaction in which the compound of interest (M) loses an electron, thereby forming a radical cation. 

The protonated molecules are much less energetic than the related radical cations formed during electron impact and are less prone to fragmentation. Both El and Cl require volatile samples. This puts a tremendous limitation on the types of molecules that can be ionized, in particular, compounds found in biological systems. 

Reference data on total energies of forms 19-23 optimized by means of different theoretical methods in the gas phase are given in Table 2. Various energetic characteristics of tetrazoles can be successfully estimated. The vertical adiabatic ionization potentials of both neutral tautomers 20 and 21 were calculated for a- and Tt-radical cations <2000CPL(330)212>. The standard molar thermodynamic functions (enthalpies, heat capacities, and entropies) of... 

GC/MS analyses most often employ one of two complementary ionization processes, electron ionization (El) or chemical ionization (Cl). This is because both El and Cl are gas phase ionization phenomena and are therefore well suited to interface with a separation technique (GC) that is also accomplished in the gas phase. The extractables profiles shown in Figs. 3-5 along with the Abietic Acid GC/MS analysis shown in Fig. 1, were acquired using GC/MS with El. The El ionization process is based on the interaction of an energetic electron beam (70 eV) with neutral analyte molecules in the gas phase, producing a radical cation, or molecular ion (M+ ) that can undergo fragmentation in the gas phase after redistribution of excess... 

Acetylene radical cations dissociation process, 49 energetics, 49,50 ionization potentials, 49,50 ... 

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