Researchers tend to use the units of kHz to represent the power of decoupling or shaped pulses in research papers. The reason for the use of this unit is to easily transfer the pulse-widths & power-levels used in the experiment from one spectrometer to another, as one can back calculate the pulse-widths & power-levels as described below. The pulse frequency that is described here (in Hz) is the precession frequency about the magnetic field experienced due to the pulse in the rotating frame. This is not the frequency of pulse (B_{0}), so please don’t confuse with this value.

The flip angle of any given pulse is given by

Where τ_{α} is the duration of the pulse to cause the flip angle α, with B_{1} being the magnitude of the magnetic field caused in the rotating frame. But the precession frequency(Hz) is defined as

Solving for B_{1} will result in

And for a 90° flip angle we can substitute α=90 or π/2, we get

For example, a 25 kHz decoupling pulse would have a 90° flip angle of 10 µs.

Now that we know how long the pulse need to be applied, we still need to figure out the power level for this pulse. Assuming a linear amplifier, we use the following equation for determining the unknown power level,

So if a calibrated pulse of 7 µs at -9.6 dB is known, a 25 kHz (ie 10 µs pulse) would require -6.5 dB power level to flip desired magnetization by 90°.

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