1 9 7 2 ) ▁in ▁theoretical ▁physics ▁from ▁Le high ▁University , ▁Pennsylvania . ▁He ▁won ▁several ▁awards ▁for ▁his ▁work ▁on ▁las er ▁science . ▁ ▁C ork um ▁is ▁both ▁a ▁the or ist ▁and ▁an ▁experimental ist . ▁In ▁the ▁ 1 9 8 0 s ▁he ▁developed ▁a ▁model ▁of ▁the ▁ion ization ▁of ▁atoms ▁( i . e . ▁pl asma ▁production ) ▁and ▁on ▁this ▁basis ▁proposed ▁a ▁new ▁approach ▁to ▁making ▁X - ray ▁las ers ▁( Opt ical ▁field ▁I on ization , ▁O FI ). ▁O FI ▁las ers ▁are ▁today ▁one ▁of ▁the ▁most ▁important ▁develop ments ▁in ▁X - ray ▁las er ▁research . ▁ ▁In ▁the ▁early ▁ 1 9 9 0 s ▁in ▁strong ▁field ▁atomic ▁physics ▁there ▁were ▁discover ies ▁of ▁high ▁harm onic ▁generation ▁and ▁correl ated ▁double ▁ion ization ▁( in ▁which ▁an ▁atom ▁can ▁abs orb ▁hundreds ▁of ▁phot ons ▁and ▁emit ▁two ▁electrons ). ▁C ork um ' s ▁Rec oll ision ▁Electron ▁Model ▁served ▁as ▁the ▁basis ▁for ▁the ▁generation ▁of ▁at to second ▁p uls es ▁from ▁las ers . ▁With ▁this ▁method ▁in ▁ 2 0 0 1 ▁C ork um ▁with ▁colle agues ▁in ▁Vienna ▁succeeded ▁in ▁demonstr ating ▁for ▁the ▁first ▁time ▁las er ▁pul se ▁lengths ▁last ing ▁less ▁than ▁ 1 ▁fem to second . ▁The ▁method ▁was ▁used ▁for ▁the ▁generation ▁of ▁higher ▁harm on ics ▁and ▁( as ▁a ▁type ▁of ▁las er ▁t unn