Define the shape from the XWIN-NMR shape tool:

• Select the desired BURP pulse from the Shapes-->Burp menu:

Excitation: G4 Cascade Inversion: G3 Cascade 90 deg: Q5 Cascade 180 deg: Q3 Cascade Your own Gaussian Pulse Cascade

and modify the following parameter if required:

Size of Shape: 1000

• Store the shape from the File-->Save As ... menu.
• Otherwhise, the shape can be generated directly from the XWIN-NMR command line:
Syntax:
st generate <shape type> <size>
or
st generate <shape type> <size> false

In the second case only amplitude data are generated.
string <shape type> = one of:

GaussCascadeG3 (Inversion), GaussCascadeG4 (Exitation)
GaussCascadeQ3 (180 deg.), GaussCascadeQ5 (90 deg.)
int <size> = shape size in number of points

Example: st generate GaussCascadeG4 1000

From the Analyze menu we can obtain the following information:

• Calculate Bandwith for Excitation [bandw2]
• Calculate Bandwith for Inversion [bandw2i]
• Calculate Bandwith for Refocusing -My [bandw2ry]
• Calculate gammaB1max on Resonance [calcb1m]
• Calculate gammaB1max off Resonance [calcb1mo]
• Calculate average Power Level [calcpav]
• Integrate Shape and compare to Square [integr]
• Integrate Shape compared to Hard Pulse [integr2]

 

Shape	G4	G3	Q5	Q3
Amplitude relative to a   square pulse of 100%	0.053	0.14	0.054	0.015
Corresponding difference to a 100%   square pulse of the same duration (in dB)	25.44	17.12	25.27	16.39

 
 

G4 Cascade  (in ms)	1	5	10	20	40	60	80	100
Maximum gammaB1   (on resonance) (in Hz)	4680	936	468	234	117	78	58.5	46.8
Corresponding 90 degree  square pulse (in ms)	0.053	0.27	0.53	1.07	2.14	3.20	4.27	5.34
Change of power level   compared to level of a 10 us hard  90 degree pulse (in dB)	14.55	28.53	34.55	40.57	46.59	50.12	52.61	54.55

 

G3 Cascade   (in ms)	1	5	10	20	40	60	80	100
Maximum gammaB1   (on resonance) (in Hz)	3589	717.8	358.9	179.4	89.7	59.8	44.9	35.9
Corresponding 90 degree  square pulse (in ms)	0.07	0.35	0.7	1.39	2.79	4.18	5.57	6.97
Change of power level   compared to level of a 10 us hard  90 degree pulse (in dB)	22.88	35.86	42.88	48.9	54.92	58.44	60.94	62.88

 
 

Q5 Cascade   (in ms)	1	5	10	20	40	60	80	100
Maximum gammaB1   (on resonance) (in Hz)	4586.3	917.2	458.6	229.3	114.7	76.4	57.3	45.9
Corresponding 90 degree  square pulse (in ms)	0.054	0.27	0.54	1.09	2.18	3.27	4.36	5.45
Change of power level   compared to level of a 10 us hard  90 degree pulse (in dB)	14.73	28.71	34.73	40.75	46.77	50.29	52.79	54.73

 
 

Q3 Cascade   (in ms)	1	5	10	20	40	60	80	100
Maximum gammaB1   (on resonance) (in Hz)	3300.8	660.1	330.1	165	82.5	55	41.3	33
Corresponding 90 degree  square pulse (in ms)	0.075	0.38	0.75	1.51	3.03	4.54	6.06	7.57
Change of power level   compared to level of a 10 us hard  90 degree pulse (in dB)	23.61	37.59	43.61	49.63	55.65	59.17	61.67	63.61

 

 More sophisticated excitation schemes can be derived from the Manipulate menu.

 The theoretical excitation and inversion profiles of the Gaussian Cascade shaped pulses can be visualized from the NMRSIM program:

A) G4 (or Q5) shaped pulse as a excitation element:

1. Select the corresponding File-->Experiment Setup-->Load from File ... menu.
2. Choose the profile.cfg configuration file.
3. Set the shape to G4.shp (or Q5.shp) in the Go-->Check Experiment parameters menu.
4. Select the Go-->Run Experiment menu.
5. The result of the simulation is displayed in the nmrsim 1 1 file into the XWIN-NMR window. Transform the data with ef (lb=1).
6. The duration of the shaped pulse can be modified by changing the P5 parameter (by default, 5 ms) in the Go-->Check Experiment parameters menu. Repeat the 4 and 5 steps to obtain the new profile.

 

B) G3 (or Q3) shaped pulse as a inversion element:

1. Select the corresponding File-->Experiment Setup-->Load from File ... menu.
2. Choose the profile180.cfg configuration file.
3. Set the shape to G3.shp (or Q3.shp) in the Go-->Check Experiment parameters menu.
4. Select the Go-->Run Experiment menu.
5. The result of the simulation is displayed in the nmrsim 1 1 file into the XWIN-NMR window. Transform the data with ef (lb=1).
6. The duration of the shaped pulse can be modified by changing the P5 parameter (by default, 10 ms) in the Go-->Check Experiment parameters menu. Repeat the 3 and 4 steps to obtain the new profile.

 

C) G3 (or Q3) shaped pulse as a refocussing element:

1. Select the corresponding File-->Experiment Setup-->Load from File ... menu.
2. Choose the spfge.cfg configuration file.
3. Set the shape to G3.shp (or Q3.shp) in the Go-->Check Experiment parameters menu.
4. Select the Go-->Run Experiment menu.
5. The result of the simulation is displayed in the nmrsim 1 1 file into the XWIN-NMR window. Transform the data with ef (lb=1).

The duration of the shaped pulse can be modified by changing the P5 parameter (by default, 10 ms) in the Go-->Check Experiment parameters menu. Repeat the 3 and 4 steps to obtain the new profile.