Multiple ionization of oxygen studied by coincident measurement

We experimentally study double and triple ionization of oxygen using a reaction microscope. The kinetic energy releases (KERs) and angular distributions are obtained through coincidentally measuring the ionic fragments of doubly or triply charged parent ions. The pathway O-2(2+) -> O+ + O+ proceeds through some excited electronic states. The KERs exhibit definite structures independent of the laser intensity and the pulse duration. However, the angular distribution of coincident O+ reflects the symmetry of the highest occupied molecular orbital (HOMO) only for fewcycle laser pulses at low intensity. The pathways O-2(2+) -> O2+ + O and O-2(3+) -> O2+ + O+ occur through some repulsive states. The KERs show a single broad peak and decrease with increasing the pulse duration. The decrease of KER comes from the stretch of the internuclear distance in intense laser fields (c) 2010 Optical Society of Americahttp://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000277560000067&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701OpticsSCI(E)EIPubMed4ARTICLE1010395-104031