来自《耶鲁大学开放课程：生物医学工程探索 第21集 第21集》
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If that's done properly, you will start如果扰动得当 -
a kind of motion in these molecules,就会使这些分子产生某种运动 -
what's called a procession, where the molecules move like a top.称为自旋 分子像陀螺那样转动 -
When they are performing当它们在磁场中 -
this kind of motion within the magnetic field,这样转动时 -
they're trying to get back to the preferred alignment它们会试图回到有序排列的状态 -
but they're doing that in this top-like fashion.但它们同时还像陀螺一样转动 -
If you have many, many atoms that are如果许多许多的原子 -
all processing in the right way都以恰当的方式自旋 -
they will emit radio frequency waves就会释放出电磁波 -
that you can detect in this cylinder outside.被圆筒外部的设备检测到 -
This shows it sort of schematically.这里用图表来表示