Protocol: Hetcorlgcp2d_1  Sequence: hetcorlgcp2d_1.c  Apptype: solidseq1d

Description:

    H to X HETCOR using FSLG during F1 followed by a Lee-Goldburg CP and
    acquisition on X with TPPM or SPINAL decoupling.

Apply a frequency offset to pw1Htilt, fslgH, pw2Htilt, pwHtilt3 to offset F1
FSLG without disturbing CP or decoupling on resonance.

Additional Software:

reset_hetcorlgcp2d_1 - This macro uses the calibrated values of pwH90 and aH90
to calculate the intial parameters for the fslgH waveform, set up 2D and set the
width of the three tilt pulses. This macro is run from the protocol.

Setup:

Load a calibrated data set and select the protocol Hetcorlgcp2d_1. For a
new nucleus calibrate CP with Onepul and Tancpx and then set up Lee
Goldburg CP with Lgcp. Then select the protocol Hetcorlgcp2d_1.

Select the desired decoupling method, TPPM or SPINAL. The manual file
onepul describes calibration of decoupling.

Lee-Goldburg CP and Decoupling should use an optimum dof value, usually used
for CP.

The macro reset_hetcorlgcp2d_1 is run from the Hetcorlgcp2d_1 protocol.  This
macro performs the next 4 steps.

1. Set aHfslg = aH90.  Set pwHtilt1 = pwH90*35.3/90.0.  pwHtilt2 =
pwH90*54.7/90.0, pwHtilt3 = pwH90.  aH90 governs the amplitude of the
three tilt pulses.
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.

The parameter pwHfslg is rounded to a 100 ns grid. The value of aHfslg
is readjusted slightly to accommodate the rounding of pwHfslg so that
it has an exact 360 degree flip angle.

Set pwX180 = 0.0 to not place an X refocusing pulse in the middle of the
F1 delay.  Most HETCOR's are run without a refocussing pulse.  A
refocusing pulse is only desirable if the X-H J-coupling is limiting
proton resolution.  MAS is adequate to remove the X-H dipolar
interaction.   If a refocusing pulse is desired then the spin rate must
be synchronized with the F1 dwell so that the refocusing pulse falls at
a multiple of the rotor period

For pwHtilt1, fslgH, pwHtilt2 and pwHtilt3, set the parameter with "of"
prefixto -1000 to -5000.  The F1 spectrum will be to the left of the
center and FSLG resolution will be the best with this offset if phase
transient is present.  There may be a center spike in F1. Be sure all
lines are to the left of the spike.

Collect a 2D dataset and process with wft2da.  Adjust ni to accommodate
greater or lesser proton resolution of the sample in F1.

HETCOR is very sensitive to phase transient on the proton channel. Side
effects of a large transient are a short T2 and an offset of the
spectrum in F1.  It is recommended that one spend significant effort to
remove phase transient for HETCOR.  The procedure for phase-transient
removal is in the manual file tunerp.

A good sample for a HETCOR setup is natural abundance glycine. A quick
HETCOR can be ni = 64, nt = 4, d1 = 1 and ss = 4.  Hetcorlgcp2d_1 works
best with spin rate of 8 to 14 kHz.  Calibrate the pwH90 = 2.5 us to do
100 kHz FSLG during F1 if the probe has the appropriate specification.
With a good result one will see a substantial splitting in the two upfield
methylene lines - from 20% to the baseline depending upon the probe and
calibration. In a Solenoid probe HETCOR can be improved by constricting
sample to 50% of the coil width.

The indirect axis of HETCOR is scaled by the value scalesw1 = sqrt(3).
It will be necessary to adjust scalesw1 to obtain the correct ppm scale.
A rough calibration with glycine is obtained by putting two cursors on 
the two methylene lines of glycine. On the command line type scalesw1 =
dfrq/delta.  In general, set two lines with a known ppm difference ?ppm
and set scalesw1 = ?ppm*dfrq/delta where ?ppm is the shift difference.

To reference F1 of a scaled HETCOR spectrum put a cursor on the peak
with a known ppm value and type rl1(ppm*dfrq/scalesw1). Note that
HETCOR spectra are displayed with axis ='pd' and refsource = 'dfrq'.

Parameter  Groups:

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

tiltnH:  Module:  yes  (n = 1,2,3)
Sequence:  hetcorlgcp2d_1.c
Description:  Implements a tilt pulse (35.3, 54.5, 90.0) on the dec2 channel
              with offset.
Parameters:  Sequence Page
       aHtilt  - amplitude of the dec pulses.
       pwHtilt - 35.3, 54.7 or 90.0 tip angle
       chHtilt = 'dec2' must be set (not shown).
       ofHtilt - offset of tilt pulse
Implementation:  shape p1 = getpulse("tiltH", 0.0,0.0,0,1);
Underscore function: _shape(p1,ph1Htilt);  ph1tilt is the overall phase
              table of the tilt pulse. 

fslgH:  Module: yes
Sequence:  hetcorlgcp2_1.c
Description:  Implements "frequency switched Lee Goldburg", FSLG,
              homonuclear decoupling on the dec2 channel.
Parameters:  Sequence Page
       aHfslg - amplitude of the FSLG dec2 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 = 'dec2' must be set (not shown).

Implementation: MPSEQ fslg = getfslg("fslgH",0,0.0,0.0,0,1);
Underscore functions: _MPSEQ functions.	  
    
cpHX:  Module:  yes
Sequence:  tancpxyr.c
Description:  Implements constant, linear or tangent-ramped cross
              polarization from dec2 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 dec2 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 = 'dec2' -  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);

Hseq:  Module:  yes
Sequence:  tancpx.c
Description:  Chooses SPINAL or TPPM decoupling on the dec2 channel
              during acquisition.
Parameters:  Sequence Page - 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 dec2 channel during
              acquisition.
Parameters:  Sequence Page
       aHtppm - amplitude of the dec2 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);

