GB904033A - Improvements in or relating to the separation or separate detection of charged particles having different specific charges - Google Patents

Abstract

904,033. Mass spectrometers. SIEMENSSCHUCKERTWERKE A.G., and PAUL, W. Dec. 23, 1958 [Dec. 27, 1957], No. 41540/58. Drawings to Specification. Class 39 (1). In a high-frequency mass spectrometer such as described in Specification 773,689, ions of different specific charges are brought into a periodic electric field the potential # of which has the general form: #=f(t).(αx<SP>2</SP>+ #y<SP>2</SP>- γz<SP>2</SP>) and an additional alternating resonance field whose frequency is approximately a fundamental or harmonic frequency of the natural oscillation of the ions of a given specific charge is superimposed on the original field and forces the given ions on to unstable paths so as to be separated out. A frequency corresponding to half the frequency of the main field is excluded. A plurality of additional fields of different frequencies may be superimposed simultaneously. Also by varying the frequency and amplitude of the superimposed fields the beat amplitude of ions of a given specific charge may be determined. The fundamental oscillation frequency of the ions is a function of its specific charge, the magnitude of the unidirectional field, the amplitude of the first applied alternating field, the magnitude of the frequency of that field and it also depends upon the electrode spacing. Since the magnitude of the alternating field, preferably of high frequency, is the only variable a proportionality constant K exists. Exact tuning is not required since in the case of small frequency differences, the ions may be made to execute beats, the amplitude of which may become so large that separation occurs. This method is particularly suitable for rapid variation of the composition of isotope mixtures. The range of separation of the superimposed field varies with the amplitude of that field.