Fig. 2.
Two-dimensional images taken with multitone current signals (Vcurrent = 1.5 mV). Two illustrative situations are shown: the top row shows images taken with a current pulse containing 70- and 130-Hz frequencies, both with (A) the standard constant-amplitude spin lock at resonance and with (B) a ramped spin lock that increases from 70% to 130% of the resonant power (τsl = 100 ms). The bottom row shows images taken with a current pulse containing frequencies from 70 to 130 Hz, in 10-Hz increments, again (D) with and (C) without a ramped spin lock.