Kobzar Kyryl, Skinner Thomas E, Khaneja Navin, Glaser Steffen J, Luy Burkhard
Institut für Organische Chemie und Biochemie, Technische Universität München, Lichtenbergstrasse 4, D-85747 Garching, Germany.
J Magn Reson. 2008 Sep;194(1):58-66. doi: 10.1016/j.jmr.2008.05.023. Epub 2008 Jun 30.
In [K. Kobzar, T.E. Skinner, N. Khaneja, S.J. Glaser, B. Luy, Exploring the limits of broadband excitation and inversion, J. Magn. Reson. 170 (2004) 236-243], optimal control theory was employed in a systematic study to establish physical limits for the minimum rf-amplitudes required in broadband excitation and inversion pulses. In a number of cases, however, experimental schemes are not limited by rf-amplitudes, but by the overall rf-power applied to a sample. We therefore conducted a second systematic study of excitation and inversion pulses of varying pulse durations with respect to bandwidth and rf-tolerances, but this time using a modified algorithm involving restricted rf-power. The resulting pulses display a variety of pulse shapes with highly modulated rf-amplitudes and generally show better performance than corresponding pulses with identical pulse length and rf-power, but limited rf-amplitude. A detailed description of pulse shapes and their performance is given for the so-called power-BEBOP and power-BIBOP pulses.
在[K. 科布扎尔、T.E. 斯金纳、N. 哈内贾、S.J. 格拉泽、B. 卢伊，《探索宽带激发与反转的极限》，《磁共振杂志》170 (2004) 236 - 243]中，最优控制理论被用于一项系统研究，以确定宽带激发和反转脉冲所需的最小射频幅度的物理极限。然而，在许多情况下，实验方案并非受射频幅度限制，而是受施加到样品上的总射频功率限制。因此，我们针对带宽和射频容限对不同脉冲持续时间的激发和反转脉冲进行了第二项系统研究，但这次使用了一种涉及受限射频功率的改进算法。所得到的脉冲呈现出各种具有高度调制射频幅度的脉冲形状，并且总体上比具有相同脉冲长度和射频功率但射频幅度受限的相应脉冲表现更好。文中给出了所谓的功率 - BEBOP和功率 - BIBOP脉冲的脉冲形状及其性能的详细描述。
