A method of ion kinetic energy analysis is provided by forming ions including metastable ions from a vaporized sample material, accelerating the ions toward a target collector electrode through an electric field, and for an interval of time for enhancing the probability of decomposition of the metastable ions in an area along a trajectory of the ions intermediate the ion source and the electric field, varying the electric field intensity for causing daughter ions of differing kinetic energy to be successively focused at a point along the trajectory and providing a spectrum display of the intensity of the ions formed at the point in synchronism with the field variation.
Electrostatic filtration of secondary ions of mass m in a given mass ratio with a primary ion of mass M which has formed the secondary ions by fission is carried out by a method which consists in forming a singly-charged primary ion of the substance having a molecular mass M and extracting the ion at a voltage V.sub.1 with respect to ground, in causing the primary ion to cross a potential barrier V.sub.2, in producing the dissociation of said ion into at least two fragments of secondary ions, in extracting the fragment ion of mass m at a voltage V.sub.2, in carrying out a filtration in an electrostatic analyzer through which only the ions of energy eV" are permitted to pass, in detecting the ions which have thus been filtered and the mass m of which is such that ##EQU1##
A spectrometer is provided for analyzing metastable decompositions which occur in certain ions. Metastable decompositions result in a precursor ion decomposing into a daughter ion and an uncharged particle of mass. The presence of such ions determine a unique spectra for certain compounds which are difficult to distinguish using conventional mass spectrometer techniques. The spectrometer utilizes a wedge-shaped beam afforded by the use of a relatively inexpensive electrostatic lens assembly. A drift space is provided to allow precursor ions to decompose and thence be analyzed.
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.
An electron/ion coincidence technique is employed to characterize the absolute mass dependent transmission efficiency of mass spectrometers. The technique is not dependent upon the partial pressure of the sample beam or the ionization cross sections of calibrant gases.
