Ion loss processes

Ferguson E E, Fehsenfeld F C, Dunkin D B, Schmeltekopf A L and Schiff FI I 1964 Laboratory studies of helium ion loss processes of interest in the ionosphere Planet Space Scl. 12 1169-71... 

Arnold, F., and D. Krankowsky, Ion composition and electron- and ion-loss processes in the earth s atmosphere, pp. 93-127, in Dynamical and Chemical Coupling Between the Neutral and Ionized Atmosphere. Grandal, B., and Holtet, J.A., (eds.), D. Reidel Publishing Company, Dordrecht, Holland, 1977. 

Reactions which are the reverse of those mentioned here as preparative techniques are important negative-ion loss processes under some conditions. Associative detachment, collisional detachment, ion-ion recombination, and photodetachment are the reverse processes to those discussed in Sections 2.1-2.4. Several reviews of these subjects are available. ... 

The electron impact positive ion spectrum of l,2,5-oxadiazolo[3,4-/]quinoline IV-oxide 46 shows the loss of N2O2 from the molecular ion, a process that must be followed by a substantial rearrangement to enable the observed loss of propyne-nitrile. This remarkable result apparently arises through a series of H-atom shifts which relocate the dehydroaromatic moiety in the heteroring (890MS465). 

Recently, the CH4+-CH4 reaction has been investigated (9) by measuring the CH4 + disappearance cross-section rather than CH5 + formation cross-sections. Results of this work are shown in Figure 9. Two mechanisms cause a loss of CH4 + ions from the total ion yield in the methane mass spectrum. There are loss processes in the ion source which generate new ions, CH5 +, and possibly other products. Other loss... 

Fig. 5 shows the time dependence of the solid-state ion exchange process. The process has pseudo first order kinetics in the investigated conversion range for both (i) the distribution and crystallinity loss of the CdCl2 salt and (ii) the formation of new Cd,H-Y phase. The rate constant obtained for the decay of... 

We have tacitly assumed that the photoemission event occurs sufficiently slowly to ensure that the escaping electron feels the relaxation of the core-ionized atom. This is what we call the adiabatic limit. All relaxation effects on the energetic ground state of the core-ionized atom are accounted for in the kinetic energy of the photoelectron (but not the decay via Auger or fluorescence processes to a ground state ion, which occurs on a slower time scale). At the other extreme, the sudden limit , the photoelectron is emitted immediately after the absorption of the photon before the core-ionized atom relaxes. This is often accompanied by shake-up, shake-off and plasmon loss processes, which give additional peaks in the spectrum. 

Note It has turned out that medium transmission is optimal for structure elucidation. Too strong reduction of the main beam favors ion losses due to scattering, charge exchange (M -i- N M + IST") or charge stripping processes (M -I- N -> + N" ) instead of delivering additional structural information. 

Following the above general description of the McLafferty rearrangement, the peak at m/z 44 in the mass spectrum of butanal can be explained by C2H4 loss from the molecular ion. The process may either be formulated in a concerted manner (a) or as a stepwise process (b) ... 

Also shown in Fig. 10(c)-(g) are the anion yield functions for submonolayer quantities of O2 deposited onto various multilayer atomic and molecular solids. The data represent part of a study [41] on the environmental factors involved in the DEA process. As can be seen, the yield of desorbed ions can vary greatly with substrate composition. Such variations can be attributed to the so-called extrinsic factors that modify the ESD process at times before attachment and after dissociation, for example, electron energy-loss processes in the substrate and postdissociation interactions (PDI) of ions with the surrounding medium [41]. These processes can be contrasted with intrinsic factors, which... 

The dotted lines in Fig. 1 show the stopping powers for the different ions at a constant velocity in units of MeV/amu. This unit of energy is very often used in heavy ion radiolysis and it is based on the classical formula for kinetic energy, E = V2 MV, where M is the heavy ion mass. As seen in Eq. (1), the ion velocity is a dominant parameter in energy loss processes and the MeV/amu energy unit is more convenient to use than converting to absolute velocity units. Remember that MeV/amu is actually proportional to the square of the velocity. 

Photo-excited SO2 and SO2 clusters have been observed to undergo a number of excited state and ion-state processes. Ion-state studies have, for example, identified the energy threshold of the ion-state oxygen loss channel of the SO2 monomer and dimer [1], Additionally, studies investigating the metastable decay process of SO2 clusters and mixed S02-water clusters have identified the dissociation pathways and the nature of the charged core of these cationic clusters [2]. The dynamics of oxygen loss of SO2 and SO2 clusters following excitation to the C (2 A ) state, which couples to a repulsive state, have also been studied to determine the influence of the cluster environment on the dissociation process [3]. 

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