Resolution enhancement in the magnetic bottle photoelectron spectrometer by impulse electron deceleration

We present a modified time of flight magnetic bottle photoelectron spectrom eter (MBPES), designed to operate with mass-selected ion beams. It is based on a configuration in which the ion beam is coaxial with the electron flig ht tube. High resolution combined with high efficiency is achieved by apply ing impulse deceleration at the electron detachment zone immediately after detachment. The main effect of the impulse is to improve the resolution of the spectrometer by subtracting the ion velocity from the electron velocity . The impulse can also counteract the spread in the flight times caused by the alignment of the electrons in the magnetic bottle. Unlike previous desi gns of the MBPES, ultimate resolution is achieved without any loss in signa l intensity. Resolutions of 8, 25, and 48 meV were obtained for 0.28, 1.22, and 2.11 eV electrons, respectively, with 60% collection efficiency. This design also allows easy switching between high-resolution high-yield and po larization-sensitive photoelectron spectroscopy modes. Our simulations indi cate that, with careful attention to details, sub-meV resolution can be obt ained using this approach. (C) 2001 American Institute of Physics.