Reference Setting By Using Z0 Shim - JEOL JNM-ECA Series User Manual

Before repeating the above procedure, be sure to click the Undo button to cancel the
settings.
For the external reference, use the spectrum that was measured just before or was
measured immediately after the measurement of the target spectrum. If a long time
period exists between these two measurements, the error of the chemical shift be-
comes larger due to the drift of the static magnetic field.
3.6.2

Reference Setting by Using Z0 Shim

Measure the spectrum of the external-reference sample, and set up a reference by adjust-
ing Z0. When this method is used, perform the reference setting before measuring the
target sample.
We recommend that you correct Z0 periodically by this method. If the value of Z0 and
the measurement time are recorded, the average amount of drift can be calculated from
the values. Z0 drift can be corrected automatically by setting this amount of drift to the
drift canceler that is explained in the following section.
The reference setting is performed by the following procedure.
1.
Calculate the amount of drift of Z0 for an observed nucleus.
2.
Measure the reference substance, and examine the difference of the chemical
shift.
3.
Change Z0 by the value that is obtained by multiplying the amount of drift
calculated in step 1 by the difference of the chemical shift obtained in step 2.
For example, supposing that the spectrum of
Hz, the amount of change of Z0 to
a difference of 2 ppm from the correct chemical-shift value of the reference substance
chemical shifts can be adjusted by changing Z0 by 200 Hz.
NMECAXS_V50-SLD-2
3 SETTING OF INSTRUMENT CONDITIONS
13 C shifts 10 ppm when moving Z0 by 1,000
13 C will be set to 100 Hz/ppm. At this time, if there is
C,
13
3-9