Molecular Plasmas Created

A method for making ultracold plasmas out of molecules has been developed by a group led by Edward R. Grant, a chemistry professor at the University of British Columbia, in Canada (Phys. Rev. Lett. 2008, 101, 205005). Previously, such plasmas could only be made from atoms in group 1 or 2. The molecular plasmas are created by cooling a jet of gaseous material to 1 K and then ionizing it with a laser. Although Grant and colleagues worked with nitric oxide, the approach should theoretically work for any volatile substance, opening up a new field of study into the chemistry of plasmatic matter. Using the NO system, the researchers found that their plasma was composed of electrons and NO⁺ ions with a density on the order of 10¹² cm^-3—about three times denser than ultracold atomic plasmas. The molecules in the plasma also appeared to behave more like a liquid than a gas. Studying such systems could provide information on how stars make metals from gases; understanding electron transport and interactions in ultracold plasmas could provide insight into superconductivity, Grant says.