Structures of cobalt oxide cluster cations studied by ion mobility mass spectrometry

- Cobalt oxide clusters are microscopic models of useful materials.
- Structures of cluster cations were studied by ion mobility mass spectrometry.
- Structures of (CoO)3-5+ are monocyclic ring.
- Compact tower structures are found for (CoO)6,7+.
- Structural transition from ring to compact structures occurs at (CoO)6+.