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 (<lo ruJ 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-‘) achieved.