GB1100481A - Method of mass spectrometry employing a high-frequency transverse electric field - Google Patents

Abstract

1,100,481. Mass spectrometers. COMMISSARIAT A L'ENERGIE ATOMIQUE. 21 Jan., 1965 [31 Jan., 1964], No. 2722/65. Heading HID. In a mass spectrometer, a monoenergetic or constant mass ion beam is passed in series through two slits into a perpendicular, homogeneous, high frequency electric field, only those ions arriving at an exit pair of slits with zero transverse velocity being capable of passing through the latter to a collector electrode; the ion mass or velocity satisfying the latter condition depends upon the frequency of the field, which is swept over a suitable bandwidth. The ion beam passes through slits in water-cooled diaphragms 36 and 38 and between capacitor plates 2 and 4<SP>1</SP>, spaced by PTFE members 32<SP>1</SP>, the intermittent exit beam from the slits in diaphragms 40 and 42 passing to a collector 30 connected to a coaxial cable 54 and screened by an electrode 52. The collected ions follow oscillatory paths which lie on one side only of the beam axis; to eliminate unwanted ions which follow paths oscillating alternately to either side of the beam axis, the capacitor plates are asymmetrically disposed with respect to the latter. Numerical data are given, and the use of a sawtooth or square-wave, rather than sinusoidal, voltage is referred to; for these voltages, the exit slits must be displaced from the beam axis.