Atoms on the surface may also desorb. The product molecules then desorb from the surface and diffuse away. The storage trays can either desorb or absorb the hydrogen gas from the core. The nitrogen molecules desorb analytes from the surface. The process then swings to low pressure to desorb the adsorbed material. Substantial methane also continues to desorb from coal placed into storage and from abandoned mines. Generally speaking single-particle measurement instruments desorb particles one at a time using a pulsed laser.