Internal energy of +ions

Fig. 2.2 Hypothetical distribution of internal energies of ions formed in a typical beam-type instrument. Ions with dissociation rate constants <10 s" remain intact on the timescale of the mass spectrometer (10 s). Those with rate constants > 10 s" are unstable ions and fragment in the ion source, while the intermediate situation (10 10 s" ) represents metastable ions...

Internal energy of ions and internal energy distribution... 

Luo, G. Marginean, L Vertes, A. Internal energy of ions generated by MALDI. Anal. Chem. 2002, 74, 6185-6190. 

Lindinger W and Smith D 1983 Influenoe of translational and internal energy on ion-neutral reaotions Reactions of Small Transient Species ed A Fonti]n and M A A Clyne (New York Aoademio)... 

Elastic scattering. An ion/neutral interaction wherein the direction of motion of the ion is changed, but the total translational energy or internal energy of the collision partners remains the same. 

Ion/neutral reaction. Interaction of a charged species with a neutral reactant to produce either chemically different species or changes in the internal energy of one or both of the reactants. 

FIG. 4 The calculated internal energy of a 1-1 salt (line) is compared with the corresponding simulation results (open circles) obtained by Van Megen and Snook (Ref. 20). The Debye-Hiickel (DH, dashed line) and corrected Debye-Hiickel (CDH, full line) theory were used together with a GvdW(I) treatment of the uncharged hard-sphere mixture. The ion diameter was 4.25 A, the temperature was 298 K and the dielectric constant e was 78.36. 

In most cases, ion activation in the reaction region or fragmentation zone is applied to increase the internal energy of the ions transmitted from the ion source. The most common means of ion activation in tandem mass spectrometry is collision-induced dissociation. CID uses gas-phase collisions between the ion and neutral target gas (such as helium, nitrogen or argon) to cause internal excitation of the ion and subsequent dissociation... 

Here, I designates the ion core (NHJ in the case of ammonia) and L the clustering ligand (e.g. NH3). The intensity and width of the metastable ion peaks carry information on the internal energy of the parent cluster ions. 

Figure 5.12. Intensities of ion peaks in mass spectra versus internal energy of M+".

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