6.25 WLEXCH1—Wideline Solids Exchange
01-999162-00 C0402
VNMR 6.1C User Guide: Solid-State NMR
120
Macro
The macro
wlexch1
converts a solids parameter set obtained with SSECHO1 to the
WLEXCH1 spin I=1 solids exchange experiment. Power levels and
pw
are retained. If
tpwrm
is not present (as in many older parameter sets),
wlexch1
creates it and sets it to
the value of
tpwrf
. If
tpwrf
is not present,
tpwrm
is set to 4095.
It is recommended that you set the 90
°
pulse
pw
with
tpwrm
(use
s2pul1
) and obtain a
quadrupole echo spectrum (use
ssecho1
) before running
wlexch1
. The default
parameters provide a mixing period of zero and quadrupole echo pulse delay of 60
microseconds.
is a diagram of the WLEXCH1 pulse sequence.
Parameters
wlexch1
makes use of the
UNITY
INOVA and UNITYplus parameters
tpwr
,
tpwrm
,
dpwr
,
dpwrm
, and
pw
. See
for a description of these parameters.
wlexch1
is
based on the quadrupole echo pulse sequence
ssecho
, and
tau1
and
tau2
have similar
definitions.
pw
is the observe 90
°
pulse, in microseconds, pulses 1 and 4 of WLEXCH1.
magic
is a 54.7° pulse, in microseconds, pulses 2 and 3 of WLEXCH1.
mix
is the mixing period, in seconds, for development of the elliptical ridges due to
molecular motion.
phase
is set to 1,2 for hypercomplex phase sensitive detection. Use the command
wft2d(1,0,0,0,0,0,0,N)
for transformation (usually 0.5<
N
<2.0). Spin lattice
relaxation during the mixing period affects the intensities of the sine and cosine arrays
unequally. Use of
N
other than 1, corrects for unequal relaxation times. Set
N
to zero the
antidiagonal of the 2D spectrum.
tau1
is the delay, in microseconds, between pulses
p1
and
pw
of the quadrupole echo
pulse sequence.
tau2
is the exact (see NOTE below) delay, in microseconds, between the second pulse and
acquisition, set the value of
tau2
to less than
tau1
to begin acquisition before the echo,
use
lsfid
greater than 1 to begin the Fourier transform at the echo peak (see below).
NOTE: The delay to compensate for filter group delay (controlled by parameters
alfa
,
beta
, and
fb
) is not present in WLEXCH1. Adjust
tau2
or use
lsfid
to set the
beginning point of the Fourier transform.
References
Schmidt, C.; Blumich, B.; Spiess, H. W. J. Magn, Reson. 1988, 79, 269.
Figure 54. WLEXCH1 Pulse Sequence
d1
d2
mix
tau1
tau2
pw
pw
magic
magic
A
B
C
at