When xenon atoms are at their ground energy state , they repel each other and will not form a bond . When xenon atoms become energized , however , they can form an excimer ( excited dimer ) until the electrons return to the ground state . This entity is formed because the xenon atom tend to fill its outermost electronic shell , and can briefly do this by adding an electron from a neighboring xenon atom . The typical lifetime of a xenon excimer is 1 – 5 ns , and the decay release photons with wavelengths of about 150 and 173 nm . Xenon can also form excimers with other elements , such as the halogens bromine , chlorine and fluorine .