Vibrational spectroscopy of clusters using a ‘‘magnetic bottle’’ electron spectrometer

The design of a high resolution ‘‘magnetic-bottle’’-type time-of-flight electron spectrometer suitable for the study of mass-separated metal and semiconductor cluster anions is described. A high collection efficiency is achieved by using magnetic fields to guide the photoelectrons, so that vibrationally resolved photoelectron spectra can be recorded at a low laser pulse energy (<10 μJ focused to 1 mm2) avoiding multiphoton processes. Spectra of clusters with a very low relative abundance, for example the products of chemical reactions involving clusters, can be recorded and an energy resolution of 6 meV (48 cm−1) achieved.