Analysis of a Multipole State Separator and Focuser for Polarizable Molecules

Abstract

The electrostatic field of a multipole focuser, consisting of parallel rods arranged in a circle, is treated. The field equation is derived from the known field of a two‐wire line, and results are given in the form of equations that express the field in terms of practical parameters. The field and the radial gradient of a (p+q)‐pole focuser is compared to that of a p‐pole focuser in order to indicate the value of increasing the number of poles. Both a complete and a simplified set of differential equations (in cylindrical coordinates) of the path of polarizable molecules in this inhomogeneous field are also given. Based on the simplified differential equations, the path of a NH₃ molecule in the J=K=3 (M_J=3) inversion state is graphically presented.