Effects of saturation on peak shape B-53
Dead-time saturation on centroid determination shifts the measured mass to
a lower value than that calculated from the empirical formula. In the
residuals box the calibration, insufficient dead time correction causes a
systematic shift of the largest ions in the spectrum (those with the highest
degree of dead time saturation) to a position below the line of best fit
compared to the smaller ions in the spectrum (those with the least degree of
dead time saturation).
If there is too much dead time correction applied, the converse is true. Within
this particular reference file that was used to set up Np (metri.ref), the first
and second carbon isotopes of the molecular ion at 284.9949 are present. Due
to the difference in the intensity of these two ions this region of the calibration
curve can be used to set the dead time correction to the optimum value for the
system.
See also:
• Configuring the TDC settings on page B-11.
• Setting up resolution for dead time correction manually on
page B-48.
• Setting the Np multiplier on page B-50.
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