8 0 0 ▁| - ▁| Z r Ar + ▁| 2 . 7 2 ▁| D 0 ▁= ▁ 2 7 0 6   cm − 1 ▁| 3 . 0 5 0 ▁| 1 1 7 9   cm − 1 ▁| - ▁| N b Ar + ▁| 2 . 6 7 7 ▁| 3 7 , D 0 = 3 1 0 6   cm − 1 ▁| - ▁| Ag Ar + ▁| ▁| ▁| - ▁| In Ar + ▁| ▁| ▁| - ▁| Ar I + ▁| ▁| ▁| - ▁| B a Ar + ▁| ▁| 6 0 0   cm − 1 ▁| } ▁ ▁Poly atomic ▁c ations ▁ ▁Metal ▁ ions ▁can ▁also ▁form ▁with ▁more ▁than ▁one ▁arg on ▁atom , ▁in ▁a ▁kind ▁of ▁arg on ▁metal ▁cluster . ▁D ifferent ▁s ized ▁metal ▁ ions ▁at ▁the ▁centre ▁of ▁a ▁cluster ▁can ▁fit ▁different ▁geomet ries ▁of ▁arg ons ▁atoms ▁around ▁the ▁ion . ▁ ▁Arg ides ▁with ▁multiple ▁arg on ▁atoms ▁have ▁been ▁detected ▁in ▁mass ▁spect rom etry . ▁These ▁can ▁have ▁variable ▁numbers ▁of ▁arg on ▁attached , ▁but ▁there ▁are ▁magic ▁numbers , ▁where ▁the ▁complex ▁more ▁commonly ▁has ▁a ▁particular ▁number , ▁either ▁four ▁or ▁six ▁arg on ▁atoms . ▁These ▁can ▁be ▁studied ▁by ▁time ▁of ▁flight ▁mass ▁spect rom eter ▁analysis ▁and ▁by ▁the ▁phot od is soci ation ▁spectrum . ▁Other ▁study ▁methods ▁include ▁C oul omb ▁explos ion ▁analysis .