This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: An NMR spectrometer can reveal molecular structure down to the atomic level, but weak signals limit what it can see. Now, Aarhus University researchers have used AI to let the spectrometer learn the best pulse sequence directly from the sample.
Imagine trying to shepherd a group of sugar-fueled children through an amusement park. You cannot work out in advance exactly which combination of words, tone of voice, timing and body language will keep everyone moving in the right direction. The children react differently, they influence one another, and the larger the group, the harder it becomes to predict what will work.
At some point, the best strategy is simply to try something, see what happens and adjust. That is roughly the strategy the Aarhus researchers have applied to a very different problem: controlling large systems of atomic nuclei and electrons. Spin is a quantum property that makes atomic nuclei and electrons behave somewhat like tiny magnets.
It is the physical basis of nuclear magnetic resonance, NMR, and of MRI scanners. The difficulty is that only a very small excess of nuclear spins points in one direction rather than the other, which produces a weak overall signal. "NMR has the same disadvantage as MRI scanners: it is relatively insensitive.
The samples need to contain a high concentration of whatever you want to analyze," says professor Niels Chr. Nielsen from Aarhus University. Electrons can help because their magnetic moment is about 660 times larger than that of a proton.
Their spins can therefore become much more strongly ordered in a magnetic field. Using carefully designed microwave pulses, researchers can transfer some of this order from the electrons to the atomic nuclei. The technique is known as dynamic nuclear polarization, or DNP.
Extract — continue reading at the source.
