A highly sensitive electron spectrometer for crossed-beam collisional ionization: A retarding-type magnetic bottle analyzer and its application to collision-energy resolved Penning ionization electron spectroscopy

A highly sensitive electron energy analyzer which utilizes a "magnetic bott le" combined with a retarding electrostatic field has been developed for Pe nning ionization electron spectroscopy. A beam of metastable rare-gas atoms is crossed with a continuous supersonic sample beam in the source region o f the analyzer. The emitted electrons are collected by an inhomogeneous mag netic field (the magnetic bottle effect) with a high efficiency of nearly 4 pi solid angle, which is more than 10(3) times higher than that of a conve ntional hemispherical analyzer. The kinetic energy of electrons is analyzed by scanning the retarding field in a flight tube of the analyzer in the pr esence of a weak magnetic field. The velocity of the metastable atoms can a lso be resolved by a time-of-flight method in the present instrument. Examp les of Penning ionization electron energy spectra as a function of collisio n energy are presented for Ar and N-2 with metastable He*(2 S-3) atoms. Thi s instrument has opened the possibility for extensive studies of Penning io nization electron spectroscopy for low-density species, such as clusters, i ons, electronically excited species, unstable or transient species, and lar ge molecules with low volatility. (C) 2000 American Institute of Physics. [ S0034-6748(00)05108-X].