Spinning up water beams

Researchers in Israel have found a way to separate water molecules that differ only in how their hydrogen nuclei are spinning. The discovery could help boost the sensitivity of nuclear magnetic resonance (NMR) spectroscopy by up to 100 000 times.

Quantum mechanics tells us that some particles, such as electrons and hydrogen nuclei (protons) have a property known as spin. Spin is unrelated to the rotation of an object, such as a ball, in the everyday world and is more akin to a type of 'charge'. Spin is designated as either up or down, but can be fractional too. A hydrogen molecule contains two hydrogen nuclei and so can have two different forms, or spin isomers, depending on whether or not the spins are aligned parallel (ortho -hydrogen) or antiparallel (para-hydrogen). Similarly, water molecules share this property and so can exist as both ortho and para water.