Veeco MS40 Operation And Maintenance Manual page 132

AVS Standard 2.3
2.3 SCANS
A scan is usually shown as a trace on a recorder chart, the abscissa is time,
mass, voltage, gauss, etc., and the ordinate is assumed proportional to ion
current or "output". It can also be shown as a table of values, an
oscilloscope trace, etc. (The term "mass spectrum" is synonymous with
scan or mass scan.) In this standard, it will be assumed for sake of
simplicity that the scan is a recorder trace (see Sec. 7.4 "Recorder"), and
that the recorder displacements are proportional to input currents.
3.11 PEAK WIDTH, W
In a graphical spectrum, the length of the base of a peak, the base being
defined by the intersection or tangency of the legs of the peak with a
reference base line. The specification of such a reference line is an
important function of this standard. In some discussions, the symbol ³m
or ³M is used for peak width rather than W. The units of W are atomic
mass units; in some cases, a conversion of units may be necessary (see 2.3
and 4.1).
3.16 RESOLUTION
3.16.1 General Definition
The ability, or a measure of the ability, of a mass spectrometer to separate
the peaks produced by ions of different mass/charge ratios.
3.16.2 Absolute Resolution. (See General Definition above).
A measure of the ion-separating ability of a mass spectrometer, at a given
mass M, given by the peak width, W, at M :
Absolute resolution (at M) = W amu
3.16.3 Unity Resolution Mass(es).
The mass number(s) at which the absolute resolution is one (amu) or "unity".
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