One of the [[metastable state]]s of strongly non-ideal plasma is [[Rydberg matter]], which forms upon condensation of [[excited state|excited atom]]s. These atoms can also turn into [[ion]]s and [[electronelektron]]s if they reach a certain temperature. In April 2009, ''[[Nature (journal)|Nature]]'' reported the creation of Rydberg molecules from a Rydberg atom and a [[ground state]] atom,<ref>