Varian UNITY INOVA NMR, Hardware Installation, Page: 38 / 65

5.2 Wideline NMR Tests
01-999044-00 C0501 UNITY INOVA Solids Hardware Installation
37
Wideline Spectral Appearance
1. Insert wideline solids sample (Part No. 00-969104-00). Tune the probe carefully for
the
2
H frequency. If you need to, refer to the NMR Probes Installation manual for
tuning instructions.
2. Acquire a quadrupolar signal of the malonic acid-d
4
sample using the SSECHO
pulse sequence and following the instructions in the User Guide: Solid-State NMR.
Be sure to center the sample in the coil.
3. Enter
rtp('/vnmr/tests/H2wl')
to recall parameters.
4. Set the following parameters:
nt=16 d1=10 rof1=10 rof2=5 alfa=0.0
tau1=20 tau2=15 seqfil='ssecho' np=16384 lb=1000
.
The quality of the spectrum is very sensitive to acquisition and processing
parameters. Be sure that spectrum is processed in the phased (
ph
) mode, not the
absolute value (
av
) mode. If all previous tests have been successful, any spectral
imperfection is most likely due to these parameter settings and not hardware
malfunctions. When phased properly, the height of the two horns of the pattern
should differ by less than 5%.
The sample has D
2
O; therefore, you get a center spike that will phase correctly only
if
np=16384
.
5. Set
pw
to the 90° pulse for
2
H.
Figure 11 shows an example SSECHO FID using
lsfid
and correct phase. Refer
to Figure 12 for all other spectral parameters. Set
tof
on-resonance for the wideline
sample.
6. Acquire 16 transients of data.
7. Look for the following spectral characteristics:
a. The amplitude of the two “horns” (perpendicular singularities) should be
within 5% of each other. If the horns are not within the specification, the
tof
is not truly on resonance. To set the
tof
on-resonance, set the two cursors on
the horns of the wideline spectrum and enter
split
.
One cursor will be set at the middle of the broad peak. Enter
movetof
to set
the transmitter offset to this middle position of the broad resonance.
b. The “shoulders” to the very outside of the broad resonance should be clearly
visible and well-defined.
c. The broad resonance should be very symmetrical in appearance.
8. Set
compul='y'
.
Figure 11. SSECHO FID for Malonic Acid-d
6
Using
lsfid