A Dual-Disk Chopper for Time-of-Flight Measurements

Abstract

A novel dual‐disk chopper for time‐of‐flight (TOF) measurements is described. Analytical expressions relating the dual‐disk TOF signals to the density and the pertinent parameters of the speed distribution function of a molecular beam are presented. It is demonstrated that use of this new chopper simplifies greatly the experimental and data reduction procedures by obviating, for the determination of most molecular beam parameters, the need for information concerning the gate function of the chopper, the dynamic function of the detector and its electronics, and the absolute zero‐time reference point.