Varian Solid-State NMR - Figure 54. WLEXCH1 Pulse Sequence

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. Figure 54 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 page 117 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 pwmagic magic
AB C
at