High resolution threshold photoelectron spectroscopy by electron attachment

US4158775A · kind A · utility

Inventors

• Robert A. Administrator of the National Aeronautics and Space Frosch · La Cañada Flintridge, US
• Ara Chutjian · La Cañada Flintridge, US
• Joseph M. Ajello · Arcadia, US

Key dates

• Filing date: Nov 30, 1977
• Grant date: Jun 19, 1979
• Expiry date: Nov 30, 1997

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N27/64
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A system for determining the stable energy levels of a species ion, of an atomic, molecular, or radical type, by application of ionizing energy of a predetermined level, such as through photoionization. The system adds a trapping gas to the gaseous species to provide a technique for detection of the energy levels. The electrons emitted from ionized species are captured by the trapping gas, only if the electrons have substantially zero kinetic energy. If the electrons have nearly zero energy, they are absorbed by the trapping gas to produce negative ions of the trapping gas that can be detected by a mass spectrometer. The applied energies (i.e. light frequencies) at which large quantities of trapping gas ions are detected, are the stable energy levels of the positive ion of the species. SF.sub.6 and CFCl.sub.3 have the narrowest acceptance bands, so that when they are used as the trapping gas, they bind electrons (to form negative ions) only when the electrons have very close to zero kinetic energy.