Charging retention

In the mass spectrum (Figure 6) of 3-deoxy-l,2 5,6-di-0-isopropyli-dene-D-xt/Zo-hexofuranose (9) the fragmentations described above are found at m/e 229, 171, 143, 111, and 101. The fragments at m/e 143 and 101 arise by cleavage of C-4-C-5 with charge retention on C-4 and C-5, respectively (see Equations 17 and 18). Scheme 2 summarizes the losses of a methyl group, acetone from the second cyclic ketal function, and... 

Once again no molecular-ion peak is seen, but the M-CH3 peak is prominent at m/e 189 in Figure 7. An important peak at m/e 159 from C-4-C-5 cleavage with charge retention on C-4 establishes the presence of a furanose ring and of a 6-deoxy function. Charge retention on C-5 leads to the ion at m/e 45 (see Equations 19 and 20). 

Low initial cost and excellent charge retention, up to five years... 

J. Daniel-Ivad, K. Tomantschger, Charge retention of Hg-free RAM cells, Proc. 184th Meeting of the Electrochem. Soc., Oct. 1993. 

Side-chain fragmentation with charge retention on the iV-terminus... 

Cleavage of (O—C) Bonds with Charge Retention on the Oxygen Atom Carrying Part... 

Note The term a-cleavage for this widespread radical-site initiated process with charge retention can be misleading, because the bond cleaved is not directly attached to the radical site, but to the next neighboring atom. 

The McLafferty rearrangement itself proceeds via charge retention, i.e., as alkene loss from the molecular ion, but depending on the relative ionization energies of the respective enol and alkene products, the charge migration product, i.e., the corresponding alkene molecular ion is also observed. This is in accordance with Stevenson s rule (Chap. 6.2.2). 

Studying the competition of McLafferty rearrangement either with charge retention or charge migration and double hydrogen transfer has revealed that ion-neutral complex intermediates (Chap. 6.12) can also play a role for the latter two processes. [102]... 

Another problem still to be solved in polymer batteries is the self-discharge of the polymer electrode in common electrolyte media. Effectively, the majority of the polymer electrodes show a poor charge retention in organic electrolytes. In situ spectroscopic measurements (Scrosati et al., 1987) have clearly demonstrated the occurrence of spontaneous undoping processes. A typical example is illustrated in Fig. 9.17 which is related to the change of the absorbance of doped polypyrrole upon contact with the electrolyte. 

Eiceman et d. [23] determined that mixtures of product ions, M 02 and (M-H), can be observed when ion formation and determination are fast, as with an atmospheric pressure ionization (API) mass spectrometer. In contrast, usually (M—H) or M-02 (but not both) is observed with explosives in IMS drift mbes where residence times for ions are Sms or greater, enough time for proton abstraction to be complete [24]. Alternatively, the M-02 ion may undergo dissociation with charge retention by the analyte molecule as shown in Eq. (3) and Figure 6 ... 

Fig. 6.S Charge retention in nickel-cadmium cells after prolonged periods of open circuit. (By courtesy of Chloride Alcad.)...

The sealed nickel-metal hydride cell (more consistently metal hydride-nickel oxide cell) has a similar chemistry to the longer-established hydro-gen-nickel oxide cell considered in Chapter 9. In most respects (including OCV and performance characteristics), it is very similar to the sealed nickel-cadmium cell, but with hydrogen absorbed in a metal alloy as the active negative material in place of cadmium. The replacement of cadmium not only increases the energy density, but also produces a more environmentally friendly power source with less severe disposal problems. The nickel-metal hydride cell, however, has lower rate capability, poorer charge retention and is less tolerant of overcharge than the nickel-cadmium cell. 

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