Abstract: There is disclosed a direct imaging type SIMS (secondary ion mass spectrometry) instrument having a mass analyzer comprising superimposed fields. The superimposed fields consist of a toroidal electric field and a uniform magnetic field substantially perpendicular to the electric field. In said electric field, the central orbit of the ion beam is located in an equipotential plane. The mass analyzer causes an image of the region on the sample bombarded with a primary beam to be focused onto a two-dimensional detector to form a mass-filtered ion image. The SIMS instrument can operate in a mode where only the intensity of the magnetic field of the mass analyzer is set equal to zero. In this mode, only ions having a selected energy within a certain energy bandwidth produce an image, that is, an energy-filtered ion image is formed.

Abstract: A double-focusing mass spectrometer comprising a Wien filter and a homogeneous magnetic field. Daughter ions produced from parent ions of a certain ionic species differ in mass but have velocities substantially equal to that of the parent ions. The Wien filter is set up such that the velocities of the daughter ions satisfy the Wien condition. Thus, the daughter ions originated from the specified parent ions pass through the filter and are dispersed according to mass by the homogeneous magnetic field and focused into a focal plane. A two-dimensional ion detector is disposed along this focal plane in order to simultaneously detect said daughter ions and to obtain a spectrum of the daughter ions.

Abstract: Detection of unknown daughter ions using a mass spectrometer in which two mass spectrometric units are coupled together. The spectrometric unit in the front stage has either an electric field or superimposed fields. The spectrometric unit in the rear stage has superimposed fields. The voltage Vdx.sub.2 necessary to produce the electric field in the front stage and the voltage Vdx.sub.1 necessary to produce the electric field of the superimposed fields in the rear stage when daughter ions having known mass and energy are detected are found. Further, the voltage Vdx.sub.2 ' necessary to produce the electric field in the front stage and the voltage Vdx.sub.1 ' necessary to produce the electric field of the superimposed fields in the rear stage when unknown ions are detected are found. Both the mass and the energy of the unknown ions can be determined from these four voltages.

Abstract: A process of obtaining spectra of daughter ions which are produced by collision of sample ions with neutral molecules for dissociating the sample ions in a collision chamber disposed in an ion path to thereby provide a structural analysis of organic compounds. To carry out this process, a mass spectrometer is used which has mass spectrometric units located before and after the collision chamber. The spectrometric unit located behind the chamber has superimposed magnetic field B and electric field E perpendicular to the magnetic field. Daughter ions having a mass m.sub.x produced from parent ions having a mass m.sub.0 inside the chamber are detected and measured by sweeping the voltage Vd.sub.x for producing the electric field or the intensity B.sub.x of the magnetic field singly or sweeping both in an interrelated manner so as to satisfy the relation ##EQU1## where V.sub.00 is the voltage for producing the electric field used to detect the parent ions having infinitely large masses, B.sub.

Abstract: A mass spectrometer and process for using same comprises an ion source, a first field, a second field and a field-free region between the first and second fields. Parent ions are mass-selected by said first field and daughter ions are formed in the field-free region by ion dissociation or ion fragmentation. The daughter ions are dispersed by the second field. Superimposed electric and magnetic fields are used as the second field, the intensity of said magnetic field being changed from a first stage to a second stage and the intensity of said electric field being swept under both stages. Both energy and mass of the daughter ions can be measured by this mass spectrometer.

Abstract: A mass spectrometer comprising superimposed electric and magnetic fields arranged substantially at right angles. The central orbit of the ion beam produced by an ion source is located on an equipotential surface in the electric field. The ion beam is accelerated by a means for producing a constant accelerating voltage. The electric field is swept by a sweep means. The change of the focal length of the superimposed field when the electric field is swept by said sweep means is compensated by a compensating means, thereby providing a mass spectrometer capable of measuring ions having a wide range of mass to charge ratios and capable of scanning at high speed and having a high accuracy mass marker.