Protocol hssmall  Sequence: hssmall.c  Apptype: solidseq1d

Description:

Provides the sequence "{XYYXXYYX}N" with small angle adjustments to X
and Y for measurements of small angle phase difference. ph2Xhssmall is
the difference between the "Y" phase deviation and the "X" phase
deviation.  ph1Xhssmall is the "X" phase deviation. Set scalesw =
90.0 *8.0*tauXhssmall*1e-6 with axis = 'h' to display "degrees"
from - 45.0 to 45.0. 

Note that for VNMRS the actual spectral width is set by the DDR. Use only 
values of tauXhssmall such that sw = 1.0/(8.0*tauXhssmall*1e-6). A value 
of 10 us works. 

Additional Software:

reset_hssmall - Uses the calibrated values of pwX90 and aX90 to calculate
the initial calibrations for hssmallX and it is run from the protocol.

hs90anal(phase,step) - A macro to calculate phases. Processs an array of
spectra obtained with a constant phase jump, ph2Xhssmall, using an array of
starting phases, ph1Xhssmall. The argument "phase" is the constant phase
jump and "step" is the step of starting phase in the array. With one
argument, step has a default of 1.0 degree.

Process the data with wft('dodc') with a full sinebell and absolute value
mode. Display the upper sideband and set the threshold to pick the peak. The
macro picks each peak and records "degrees".  normalize =  'y' averages the
data to the assigned step. hard copy = 'y' produces a plot.

hssmallanal - A macro to calculate phase deviation of an array of phase
jumps. Processs an array of spectra obtained with an array of phase jumps, 
ph2Xhssmall, and a constant starting phase, ph1Xhssmall. Each point is the 
error from the set phase jump. The accuracy of HS90 is *not* independent of 
the phase jump unless the sequence is perfectly calibrated. Use this macro 
only over small arrays of phase. 

hssmallanal2 - A macro to calculate actual phase from an array of phase
jumps. Processs an array of spectra obtained with an array of phase jumps, 
ph2Xhssmall, and a constant starting phase, ph1Xhssmall. Each point is the 
actual phase . The accuracy of HS90 is *not* independent of the phase jump 
unless the sequence is perfectly calibrated. Use this macro only over small
arrays of phase. 

Procedure: 

Place a sample of water (20% H2O in D2O to avoid overload)in the probe
and tune to 1H. Calibrate a 90-degree pulse and set the water on 
resonance. Obtain reasonable shims. Type Hsmall to setup the sequence. 

Determine whether the defaults are appropriate. A Liquids probe may need 
longer values of pwXhssmall and tauXhssmall. The defaults set a 25% duty 
cycle for hssmall. The value of pwXhssmall should not exceed the decoupler
spec, and one should be cautious if the acquisition time exceeds the spec
for maximum time on. The maximum time on is for a 100% duty cycle, lower 
duty cycle may allow you to increase the time, but be cautious - there are 
no promises. 

Be sure the DDR sets sw = 1.0/(8.0*tauXhssmall*1e-6). 

For good stability run Hssmall with a long recycle, to avoid RF heating 
of the probe.  Set an array of 1 scan and determine a d1 for which the 
result is stable. 

Run a test array over aXhssmall to calibrate the result for a fixed phase.
One will see a center peak with sidebands at the phase jump angle. The macros 
work with the upper sideband. HS90 is very sensitive to amplitude changes. 
Be sure you are in a region of stable amplitude calibration. Also be sure you 
are on resonance.  HS90 is very unstable off resonance. 

To measure stability as a function of starting phase set ph2Xhssmall to the 
desired phase jump and array ph1Xhssmall over the desired starting phases. 
Use hs90anal to process. 

To measure an array of phase jumps set ph1Xhssmall to a fixed starting phase 
and array ph2Xhssmall over the desire phase jumps. Use hssmallanal and 
hssmallanal2 to process. 

Parameter Groups:

scaleX:  (processing)  Module:  no
Sequence:  br24.c
Description:  Shows the F2 scale factor, scalesw, for evolution of the
              obs nuclei under a multiple-pulse waveform.
Parameters:  Sequence Page
       scalesw - the F2 scale factor. Typically scalesw is the inverse
              of the mutiple-pulse scale factor.

hssmallX:  Module:  yes
Sequence:  hssmall.c
Description:  Implements HSSMALL on obs with acquisition in the first 
              window.
Sequence: hssmall.c
Parameters:  Sequence Page
       aXhssmall - amplitude of obs pulses.
       pwXhssmall - 90-degree flip on obs.
       r1Xhssmall - prepulse delay (similar to rof1).
       r2Xhssmall - postpulse delay (similar to rd or rof2).
       r3Xhssmall - T/R-to-rcvron delay (must equal rof3 or 2.0 us if
              rof3 is not defined).
       tauXhssmall - time for one "one-tau" window and pulse.
       npaXhssmall - number of 100 ns ticks in the detection window.
       ph1Xhssmall - small angle phase 1
       ph2Xhssmall - small angle phase 2
       chXhssmall = 'obs' must be set (not shown).
Implementation:  WMPA hs = getmrev8("hssmallX");
Underscore function: _hssmall(hssmall,phXhssmall);  phXhssmall is the overall
phase table.

