Hi, long time user, first time poster. A while back someone posted a great question https://www.physicsforums.com/showthread.php?t=33584 To paraphrase, can you explain on a spin-by-spin level exactly how a 181* pulse is possible? You always hear this really intuitive explanation of NMR pulses as a net imbalance of low energy state spins and as you excite them with RF energy, they go to high energy state. This causes the net imbalance to tip from 0*, to 180*. However, this explanation seems to only describe up to 180* pulses. The answers from 2004 trend towards bulk response and arm waving as soon as the questioner really presses on a 181* pulse. So what's going on? Is the common explanation actually lacking in completeness. This seems like such a great little thought experiment. Thanks for any insight.