RESONANT ION PAIR FORMATION (RIP) IN ELECTRON-MOLECULAR ION COLLISIONS W. Zong$^\1,2$, G. Dunn$^\1$, N. Djuric$^\1$, M. Larsson$^\2$, A. Al-Khalili$^\2$, A. Neau$^\1,2$, A. Derkatch$^\2$, L. Vikor$^\2$, W. Shi$^\2$, A. Le Padellec$^\3$, S. Rosen$^\2$, H. Danared$^\4$, M. af Ugglas$^4$ $^\1$JILA, Univ. of Colorado and NIST, Boulder, CO 80309-0440, USA $^\2$Dept. Molec. Physics, Stockholm Univ., Box 6730, S-113 85 Stockholm, Sweden$^\3$Univ. Cath. de Louvain, Inst. de Phys., 2-B1348, Louvain-la-Neuve, Belgium $^\4$Manne Siegbahn Laboratory, Frescativagen 24, S-104 05, Stockhom, Sweden Resonant ion pair formation (RIP) has been observed and measured in the Stockholm heavy-ion storage ring, CRYRING for electrons impacting on HD$^\+$ and HF$^\+$, and an upper limit was put on RIP for OH$^\+$. The HD$^\+$ results are characterized by a spectacular set of 14 resonances which we divide into three groups. We can speculate on the formation mechanisms for two of the groups, but for the third group any reasonable hypothesis escapes us. The HF$^\+$ ion is particularly interesting because of certain degeneracies that occur.