Ion-molecule reaction chemistry of Fe+ with NO: excited-versus ground-state reactions

Abstract

Ion-molecule reactions of excited- and ground-state Fe[sup +] with NO are reported. The charge-exchange and clustering ion-molecule reactions of Fe[sup +] with Fe(CO)[sub 5] are used to study the reaction dynamics of metastable versus ground electronic state Fe[sup +] ions. The ground-state [sup 6]D(4s[sup 1]3d[sup 6]) Fe[sup +] ions are unreactive with NO. Conversely, the metastable electronic states react with NO to form charge-transfer product ions (NO[sup +]) and radiative association adduct ions [Fe[sup +](NO)] and by the collisional relaxation process. The collisional relaxation process gives rise to the ground-state [sup 6]D(4s[sup 1]3d[sup 6]) and excited-state [sup 6]S(4s[sup 2]3d[sup 5]) Fe[sup +] ions. The [sup 6]S(4s[sup 2]3d[sup 5]) Fe[sup +] ion is unreactive with NO and constitutes approximately 6% of the Fe[sup +] ion population. Molecular orbital concepts are used to explain the lack of reactivity for the [sup 6]S(4s[sup 2]3d[sup 5]) Fe[sup +] ions and also the collisional relaxation process by the high-lying 4s[sup 1]3d[sup 6] states to form the [sup 6]S(4s[sup 2]3d[sup 5]) Fe[sup +] ions. 31 refs., 5 figs.