field-free region

field-free region

A region in the flight path of an ion from the source of the mass spectrometer through the mass analyser to the detector which has no specific magnetic or electric field, as occurs in the ion path between the electric and magnetic analysers in a double-focusing mass spectrometer, or between the source and the first sector of single- and double-focusing mass spectrometers.

Unimolecular ion dissociations in these regions may give rise to signals in the mass spectrum recorded under normal conditions (metastable ions), or can be specifically analysed.
References in periodicals archive ?
More specifically, for the experimental data measured in the field-free region, the main result is that the characteristic time of purely photoinduced reorientation, [t.sub.e], strongly depends on the initial irradiation doses [t.sub.e] [approximately equal to] 23 min at [D.sub.p] = 0.27 J/[cm.sup.2] and [t.sub.e] [approximately equal to] 85 min at [D.sub.p] = 0.55 J/[cm.sup.2].
Figure 9(a) shows how the histogram of the easy axis angle evolves with the exposure time in the field-free region (E = 0 V/[micro]m) at [D.sub.p]= 0.07 J/[cm.sup.2].
In addition, as opposed to the case of field-free region, no disordering effects are observed within the interelectrode gaps (see Figure 9(b)).
Perhaps a more immediate concern is the possible causal relationship between field-free regions having high potentials and the anomalous adverse health changes that have been observed in such regions.

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