Varian Solid-State NMR - FLIPFLOP - Pulse Width and Phase Transient Calibration; Figure 22. Pulse Sequence for Flipflop.C

4.9 FLIPFLOP - Pulse Width and Phase Transient Calibration
01-999162-00 C0402 VNMR 6.1C User Guide: Solid-State NMR 68
4.9 FLIPFLOP - Pulse Width and Phase Transient
Calibration
The flipflop.c pulse sequence (Figure 22) is the standard sequence for multiple-pulse tune
up. It is applicable for UNITYplus and
UNITY
INOVA as well as UNITY and VXR-S with
a Sync Module. It is used for measurement of the pulse width and removal of phase
transient.
Macro
The macro flipflop calls the sequence and a parameter set.
Parameters
pw is the 90
o
pulse length, in microseconds.
phase1 is the phase of the first 90-degree pulse, and is set to 0 (x).
phase2 is the phase of the second 90 degree pulse. It is set to 0 (x) for FLIPFLIP and 2 (-x)
for FLIPFLOP.
trig='y' for UNITY and VXR-S with a Sync Module. Otherwise trig='n'.
np is the number points and np=128 or 256.
tau is interpulse delay, in microseconds, including pw. The minimum tau is about 7.0
µs
when pw=1.5
µs. See rof1 and rof2.
rof1 is the amplifier unblanking time before each pulse. The receiver is also immediately
blanked and a T/R switch if present is placed in transmit mode. Set rof1=1.5 µs.
rof2 is the receiver unblanking time after each pulse. A T/R switch is placed in receive
mode immediately. For
1
H the receiver comes on after about 2.0 µs. For lowband nuclei
the receiver is set to come on after 8.0 ms. these two times are controlled by hardware
adjustment in the magnet leg. Set rof2=0.2
µs for a High-Power preamp. Set
rof2=0.5
µs for a Solids
1
H/
19
F preamp.
dtau rof1rof2
acq
dtau rof1rof2
acq
tau tau
d1
pw
pw
[phase1] [phase2]
'np'/4 times
Figure 22. Pulse Sequence for flipflop.c