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Combining Shaped Pulses and Pulsed Field Gradients Excitation Sculpting

6 COMBINING SHAPED PULSES AND PULSED FIELD GRADIENTS EXCITATION SCULPTING  [Pg.308]

It is rather tedious to move the spectral window every time we want to select a peak with a shaped pulse, but it is necessary as the center of the Gaussian excitation profile is at [Pg.309]

SHAPED PULSES, PULSED FIELD GRADIENTS, AND SPIN LOCKS [Pg.312]

The only problem is that we need to find this magic selective pulse that delivers a 180° rotation everywhere but the center of the spectral window. There are shaped pulses that do this, but it turns out that the simplest solution is a series of six hard pulses separated by equal delays. If we divide the 90° rotation into 13 small rotations of equal angle, the sequence is [Pg.312]

Now let s return to the 3-9-19 sequence. For the water peak, it s simple. As there is no evolution during the r delays, it is just a sequence of six pulses whose rotation is exactly balanced between ccw rotations (3-9-19) and cw rotations (19 — 9 — 3). The net rotation is zero and the water magnetization ends up on the +z axis, where it started. Water is not affected by the pulse train. The same is true if the offset is v0 — vr = 1/r [Pg.312]




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Excitation pulse, shaped

Excitation pulsed

Excitation sculpting

Excited gradient

Exciting field

Exciting pulse

Field excitation

Field gradient

Field pulses

Gradient pulse

Gradient pulsed

Pulse excitation

Pulse field gradient

Pulse field gradients, pulsed

Pulse shape

Pulsed field gradient

Pulsed fields

Sculpt

Shaped gradient pulses

Shaped pulse

Shapes Combined

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