Protocol: Pisema2d  Sequence: pisema2d.c  Apptype: solidseq1d

Description: 

A sequence to correlate X chemical shift with the X-H dipolar 
interaction in the rotating frame.  PISEMA is used to characterize 15N-
1H dipolar interactions for static, oriented membrane protein samples. 

Additional Software: 

reset_pisema2d - This macro uses the calibrated values of pwH90 and 
aH90 to calculate the initial parameters for the fslgH waveform and 
sets up 2D parameters.  This macro is run from the protocol. 
 
Setup:

Load a calibrated data set and select the protocol Pisema2d.   For a 
new nucleus calibrate CP with Onepul and Tancpx and then select 
Pisema2d.  
   
Select the desired decoupling method, TPPM or SPINAL. The manual file 
onepul describes calibration of decoupling.

The macro reset_pisema2d performs the next 5 steps. 

1. Set aHfslg = aH90.  Set pwHtilt = pwH90*35.3/90.0.  pwHtilt has the 
same amplitude as aH90. 
2. Set pwHfslg = sqrt(2/3)*4.0*pwH90.  pwHfslg is rounded to a 100 ns 
grid and aHfslg is adjusted to accommodate the change. 
3. Set ofdHfslg = 1.0/(sqrt(3)*pwHfslg*1e-6)).  Note that ofdHfslg = - 
1.0/(sqrt(3)*pwHfslg*1e-6)) is incorrect. 
4. Set sw1 = 1.0/(8.0*pwHfslg*1e-6). Set ni = 64 and phase = 1,2. 
5. Set aXfslg = aX90, pwXfslg = pwHfslg, ofdXfslg = 0.0. 

Set scalesw1 = 0.801

Collect a 2D dataset and process with wft2da.  

PISEMA is very sensitive to phase transient on the X and H channels. 
Side effects of a large transient are a short T2 in F1 and potential 
amplifier overload on X from a large reflected power during phase 
changes. It is recommended that one spend significant effort to remove 
phase transient for PISEMA.  A typical reference compound is a crystal 
of 15N labelled N-acetyl valine (NAV).  One should be able to sustain 
the F1 signal for 3 to 5 ms if phase transient is controlled. Details 
about removal of phase transient are described in the manual file 
tunerp. 
 
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);  

fslgH:  Module:  yes 
Sequence:  tancpxfslg.c      
Description:  Implements "frequency switched Lee Goldburg", FSLG, 
              homonuclear decoupling on the dec channel.
Parameters:  Sequence Page
       aHfslg - amplitude of the FSLG dec pulses.
       pwHfslg - 360-degree flip on dec, off resonance (the length of 
              each of the two FSLG pulses).  
       nHfslg - FSLG cycles represented in the .DEC file. 
       ofdHfslg - +/- frequency offset of alternating pulses, a 
negative value indicates that 
              the first pulse has negative offset. 
       ofHfslg - overall frequency offset.
       chHfslg = 'dec' must be set (not shown). 
Implementation: MPSEQ fslg = getfslg("fslgH",0,0.0,0.0,0,1); 
Underscore functions: _MPSEQ functions.   

fslgX:  Module:  yes 
Sequence:  none      
Description:  Implements "frequency switched Lee Goldburg", FSLG, 
              homonuclear decoupling on the obs channel.
Parameters:  Sequence Page
       aXfslg - amplitude of FSLG obs pulses.
       pwXfslg - 360-degree flip on obs, off resonance (the length of 
              each of the two FSLG pulses).  
       nXfslg - FSLG cycles represented in the .DEC file. 
       ofdXfslg - +/- frequency offset of alternating pulses, a 
              negative value indicates that the first pulse has negative offset. 
       ofXfslg - overall frequency offset.
       chXfslg = 'obs' must be set (not shown). 
Implementation: MPSEQ fslg = getfslg("fslgX",0,0.0,0.0,0,1); 
Underscore functions: _MPSEQ functions.  scalef1H:  (processing) 

scalef1H: (processing)  Module:  no 
Sequence:  hetcorlgcp2d.c
Description:  Shows the F1 scale factor, scalesw1, for evolution of the 
              dec nuclei under a multiple-pulse waveform.
Parameters:  Sequence Page
       scalesw1 - the F1 scale factor. Typically scalesw1 is the 
              inverse of the mutiple-pulse scale factor. 
 
Hseq:  Module:  yes 
Sequence:  tancpx.c      
Description:  Chooses SPINAL or TPPM decoupling on the dec channel 
              during acquisition.
Parameters:  Sequence Page - the Hspinal and Htppm groups overlap. 
       Hseq - chooses the decoupling sequence, TPPM or SPINAL. 
Implementation:  DSEQ dec = getdseq("H");  The router implements 
              getspinal() or gettppm(). 
Underscore functions: _dseqon(dec); runs _tppm(); or _spinal();
              _dseqoff(dec); runs decprgoff();  

Hspinal:  Module:  yes 
Sequence: tancpx.c  
Description:  Implements SPINAL decoupling on the dec channel during 
              acquisition.  
Parameters:  Sequence Page
       aHspinal - amplitude of the dec channel. 
       pwHspinal - approximate 180-degree flip angle on resonance. 
       phHspinal - +/- small angle phase. SPINAL64 is implemented with 
              phases = +/- 1.0, +/- 1.5 and +/-2.0 times phHspinal. 
       chHspinal = 'dec' must be set (not shown).
Implementation: SPINAL dec = getspinal("H"); or DSEQ dec = 
              getdseq("H");  
Underscore functions: _spinal(dec); and decprgoff(); or _dseqon(dec); 
              and _dseqoff(dec);   

Htppm:  Module:  yes
Sequence:  tancpx.c
Description:  Implements TPPM decoupling on the dec channel during
              acquisition.
Parameters:  Sequence Page
       aHtppm - amplitude of the dec channel. 
       pwHtppm - approximate 180-degree flip angle on resonance. 
       phHtppm - +/- small angle phase. TPPM is implemented 
              with phases = +/- 1.0 times phHtppm for alternating pulses.  
       chHtppm = 'dec' must be set (not shown).
Implementation: TPPM dec = gettppm("H"); or DSEQ dec = getdseq("H");   
Underscore functions: _tppmon(dec); and decprgoff(); or _dseqon(dec); 
              and _dseqoff(dec);   
