J

Same Area as

Gaussian

28.31 Hz

I yBt/27i

50.45% of area of rectangle

180° Rectangular Pulse

Figure 8.50

on the Bruker to be 15 |xs, corresponding to a 180° pulse width of 30 |xs. We need to know the pulse power in decibels that will give us a 180° rectangular pulse of duration 17.66 ms:

We use common sense to find the correct power level: We know we want lower power, and for Bruker that means a larger number. So we add this to 3 dB to get a power setting of 58.4 dB. As this power level corresponds to the maximum power of the Gaussian shaped pulse, we can set this power level for our shaped pulse and get a 180° rotation. This would be the starting point for the pulse calibration.

Further Reading

1. Bauer C, Freeman R, Frenkiel T, Keeler J, Shaka, AJ. Gaussian pulses. J. Magn. Reson. 1984;58:442-457.

2. Bothner-By AA, Stephens RL, Lee J-M. Structure determination of a tetrasaccharide: transient nuclear Overhauser effects in the rotating frame. J. Am. Chem. Soc. 1984;106:811-813.

3. Braunschweiler L, Ernst, RR. Coherence transfer by isotropic mixing: application to proton correlation spectroscopy. J. Magn. Reson. 1983;53:521-528.

4. Hurd RE. Gradient-enhanced spectroscopy. J. Magn. Reson. 1990;87:422-428.

5. Sklenaf V, Piotto M, Leppik R, Saudek V. Gradient-tailored water suppression for 1H-15N HSQC experiments optimized to retain full sensitivity. J. Magn. Reson. A 1993;102:241-245.

6. Stott K, Stonehouse J, Keeler J, Hwang T-L, Shaka AJ. Excitation sculpting in high-resolution nuclear magnetic resonance spectroscopy: application to selective NOE experiments. J. Am. Chem. Soc. 1995;117:4199-4200.

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