GB1339582A - Mass spectrometers and method of operating them - Google Patents

Abstract

1339582 Mass spectrometers ASSOCIATED ELECTRICAL INDUSTRIES Ltd 19 May 1971 [17 June 1970] 29499/70 Heading H1D A double-beam mass spectrometer, e.g. as described in Specification 1,161,432, arranged to produce two mass spectra simultaneously, is combined with spectral time displacement means for giving the spectra a relative time displacement, and displaced spectra combination means 34 for combining the relatively displaced spectra to form a single electric signal representing a combined spectrum. This signal can then be processed by a unit 36 requiring only a single processing channel 38 with one A/D converter 40. In the arrangement shown the time displacement is provided by a collector slit assembly 226 in which the slits 222 and 224 for the respective beams 18 and 20 emerging from the magnetic analyser 12 are displaced by a distance D. In an alternative arrangement (Fig. 3, not shown) the time displacement is produced by interposing a delay means, such as an electrical or ultrasonic delay line, or a continuous loop tape recorder with relatively displaced record and playback heads, between ion collector 30 and the signal combination circuit 34. In a further alternative arrangement (Fig. 4, not shown) one or both sectors of the electrostatic analyser 10 is/are split and supplied by a deflection voltage proportioning means connected to the means supplying the ion accelerating voltage to the ion sources 14 and 16, to provide a dual analyser giving the required time displacement. The spectrometer may be used for the comparative analysis of two substances, one of which may be a reference substance.