Fig. 2.

Comparison of ${\mid \text{X}}_{\text{k}}^{\text{p}}\mid$ for polyphase excitation (green dashed line) with N = 256, and | Xk |for rapid frequency scan (blue solid line) of ± 8.5 MHz. Calculations were done with B₁=1 and T=15 μs. The y axis scales linearly with B₁. The parameters were selected to correspond with experiment. The red dotted line is the limiting value for an infinitely wide scan. Resonator Q = 250 for the experiments corresponds to a 3 dB bandwidth of ±2.5 MHz which limits the bandwidth of frequencies that impact the spins. Since the signal bandwidth is much narrower than the bandwidth of the resonator, the impact of resonator Q on the excitation profile was not included in the calculation.