We demonstrate the isomer-resolved spectroscopy of gas-phase ions, with different geometries separated prior to spectroscopic probe using ion mobility techniques. Specifically, ring and chain isomers of carbon cluster anions with 10̄–12 atoms have been separated by ion mobility/mass spectrometry and examined by photoelectron spectroscopy. This methodology should also apply to other ion spectroscopies, including IR photodissociation.

• Received 22 February 2002

DOI:https://doi.org/10.1103/PhysRevLett.89.083001