Unstable high-field mobility

UNSTABLE HIGH-FIELD MOBILITY OF RUNAWAY IONS... 

The present performance of high field NMR instruments allows the recording of a spectrum in quantities of micrograms. Under these conditions, it is possible to install a flow cell of only a few microlitres into the magnet of the instrument which allows the spectra of the analytes to be recorded. The experiment is conducted with a very small flow rate of the mobile phase (D20 or CD3CN) or in the stop-flow mode. In this mode, the mobile phase is momentarily stopped in order to record the spectrum. This technique, which requires very expensive materials, is of limited use. It is used mainly to isolate and identify very unstable compounds that cannot be isolated through classical means. 

When apolar electron acceptors (p = 0) were examined the hole drift mobility increased with increasing electron affinity (EA) as can be seen from Fig. 4 and Table 1. This trend applies to all compounds listed in Table 1 However, compounds having EA exceeding 1.4 eV turned out to be chemically unstable at the high electric fields afforded for these measurements. TCNQ is a typical compound behaving in that way. 

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