Protocol: Tancpxs  Sequence: tancpxs.c  Apptype: solidseq1d

Description: 

Constant, linear or tangent-ramped cross polarization (CP) with a
choice of SPINAL16, SPINAL32, SPINAL64 or TPPM decoupling. Used
for calibration of the Hartmann-Hahn Match and calibration of
the 90-degree pulse width pwH90 with X detection.

This Version uses the MPSEQ spnlH tather than the DSEQ router.

Setup: 

Load a calibrated data set and select the protocol Tancpxs. For a 
new nucleus first use Onepul to calibrate pwX90.  Select 'H1' as 
the observe nucleus and calibrate pwX90 again for protons. Reselect
the X nucleus and copy pwH90 = pwX90 (of protons) and aH90 = aX90
(of protons) to transfer the calibrations to the decoupler. It is
helpful to calibrate pwH90 with the same value as pwX90. 

After calibration select the protocol Tancpx. Select the desired
decoupling method, TPPM or SPINAL. The manual file Onepuls describes
calibration of decoupling and the method can also be applied with 
Tancpxs. 

To run constant-amplitude CP select Shape = 'const' and Channel =
'from'.  Set aHhx to the desired proton amplitude during CP and 
set aXhx to the desired X amplitude during CP.  A good starting 
value for aXhx is a calibrated value of aX90 that produces a 
pulse width in the range 4 to 5 us.  A good value of aHhx is the
calibrated value of aH90 that produces the same pulse width as
aXhx.  After setting the match, leave pwH90 and aH90 at their 
calibrated values. pwH90 is used as the proton excitation pulse.
Optionally reset aH90 and pwH90 for a different calibration 
if that is desired.  Set the contact time tHX for maximum 
sensitivity.  A good starting value is 1.0 ms. 

Array either aHhx or aXhx to provide a fine calibration of the 
Hartmann-Hahn match. When the sample is spinning the optimum match 
will occur at two amplitudes greater and less the the Hartmann-Hahn
match and the values will diverge for faster spinning rates.  Array
pwH90 to provide a fine calibration of the proton excitation pulse. 

To run linear-ramped-amplitude CP first calibrate constant-amplitude 
CP. Select Shape = 'linear' and then set dHX = 100 to 400. The 
ramped channel is designated by Channel and can be either 'from' or 
'to' where from is protons and to is X.  The median of the ramp is 
the appropriate value aHhx (from) or aXhx (to). Do a fine calibration 
of dHX with an array. 

To run tangent-ramped-amplitude CP first calibrate linear-ramped CP.
Select Shape = 'tan' and set the value of bHX = 10 to 400. Calibrate
dHX and bHX simultaneously in a double array. Tangent-ramped CP is 
usually not used with routine samples. Note that when bHX is large
(>10000) a linear ramp and a tangent ramp are identical.  When bHX 
approaches 0 the tangent ramp approaches constant CP. Beware that
bHX > 0 and that if you go from Shape = 'linear' to Shape = 'tan'
with bHX = 0 constant CP will result. 

For all CP experiments do a fine calibration of tHX with an array. 
Nuclei with attached protons obtain maximum CP at about 1.0 ms 
or less.  Nuclei with distant protons may large values of tHX a
pproaching 10 ms or more. 

Parameter  Groups: 

90H:  Module:  no
Sequence:  tancpx.c  
Description:  Provides a 90-degree pulse on dec that can be used 
              as a preparation pulse. Also used to store the dec 
              calibration.
Parameters:  Channels Page
       aH90  - the amplitude of the pulse.
       pwH90 - the pulse length.

cpHX:  Module:  yes
Sequence:  tancpx.c
Description:  Implements constant, linear or tangent-ramped cross 
              polarization from dec to obs. 
Parameters:  Sequence Page
       shHX - 'c', constant, 'l', linear and 't', tangent shape on
               the channel designated with chHX. 
       chHX - the variable-amplitude channel, 'fr' from or 'to', to. 
       aHhx - median amplitude of the dec channel.
       aXhx - median amplitude of the obs channel.
       bHX -  +/- tangent curvature (>0 to 1.0e5).  
       dHX -  amplitude width of the ramp. A negative width sets a
              ramp that starts high and decreases in amplitude.
       tHX -  contact time
       ofHX - overall offset on the variable channel
       frHX = 'dec' -  channel with the initial polarization (must 
              be set - not shown).           
       toHX = 'obs' -  channel with the final polarization (must be
              set - not shown). 
Implementation:  CP hx = getcp("HX",0.0,0.0,0,1); 
Underscore functions: _cp_(hx, phHhx, phXhx);  
 
spnlH:  Module:  yes
Sequence:  tancpxs.c
Description:  Implements TPPM, SPINAL16 SPINAL32 and SPINAL64 as a
              MPSEQ. Used as an alternate to the DSEQ router.
Parameters:  Sequence Page
       aHspnl - amplitude of SPINAL or TPPM.
       pwHspnl - approximate 180-degree flip on dec.
       nHspnl - 2 for TPPM, 16, 32, 64 for SPINAL.
       qHspnl - Number of PULSES (not cycles!) in the .DEC file.
       ph1Hspnl - TPPM +/- phase, "phi".
       ph2Hspnl - additional SPINAL phase, "alfa".
       ofHspnl - overall frequency offset.

The Basic SPINAL cycle Q is: [(phi),(-phi)],(phi+alfa),(-phi-alfa),(phi+2alpha),
                             (-phi-2alpha),(phi+alfa),(-phi-alpha). Note that
                             the first two elements [(phi),(-phi)] are TPPM.
SPINAL repeats with: [[Q-Q]-QQ]-QQQ-Q]. where the [] include 16,32 and 64 pulses.
                     The "Supercycle" of this SPINAL is one PULSE, (not Q).
Implementation: MPSEQ spnl = getspnl("spnlH",0,0.0,0.0,0,1);
Underscore functions: _MPSEQ functions.
