Magnetic time‐of‐flight photoelectron spectrometer for mass‐selected negative cluster ions

• Published in: Review of scientific instruments 1987-11, Vol.58 (11), p.2131-2137
• Main Authors: Cheshnovsky, O., Yang, S. H., Pettiette, C. L., Craycraft, M. J., Smalley, R. E.
• Format: Article
• Language: English
• Subjects: Electron, positron and ion microscopes, electron diffractometers and related techniques; Exact sciences and technology; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Physics
• ISSN: 0034-6748; 1089-7623
• DOI: 10.1063/1.1139475

Design considerations and initial results are presented for a new type of time‐of‐flight photoelectron spectrometer which is particularly suited to the study of cold metal and semiconductor cluster anions prepared in a supersonic molecular beam. The desired cluster is extracted from the molecular beam, mass‐selected after an initial time‐of‐flight, and decelerated as it enters the photoelectron spectrometer. Photoelectrons ejected from the cluster by an ArF excimer laser are collected with >98% efficiency in an intense pulsed magnetic field of carefully controlled divergence. This divergent field parallelizes the photoelectron trajectories and maps smoothly onto a low, uniform magnetic field which guides the electrons along a 234‐cm flight tube leading to a microchannel‐plate detector. The strong magnetic fields and simple, open design provide excellent rejection of stray photoelectrons in a clean, ultrahigh‐vacuum environment. The UPS spectrum of Si2 0 − is given as an example.