Hiroshi Mima

Preparation of Pd thin film photo-cathodes using ion-beam sputtering

Abstract We have proposed a new type of vacuum gauge using a palladium (Pd) thin film as a photo-cathode for measuring vacuum pressure. A photo-induced electron was adopted in place of the thermoelectron used in a conventional ionization gauge. The Pd thin film photo-cathode was prepared on a quartz substrate using the ion-beam sputtering method. It was irradiated by ultra violet (UV) light from a deuterium lamp. The photoelectron current emitted from the Pd thin film increased with decreasing film thickness. A maximum current of 240 nA was obtained from a film of 4 nm-thickness. It was found that the ionization gauge with the Pd photo-cathode at 7 nm thickness showed a linear response in the pressure range of 10 −2 -10 Pa in an Ar gas atmosphere. The photoelectric emission from the Pd surface by UV irradiation is affected by the sputtering conditions.

On an Intrinsic Cracking Pattern in a B-A Gauge Type Ion Source

A new method is proposed here for the derivation of mass spectrum cracking pattern, which is supposed to be possessed by ions generated in a variety of electron bombardment type ion sources used in mass spectrometry.The intrinsic cracking pattern is derived from partial ionization cross section of the sample gas with the aid of l - V distribution data of the ionizing electron, which represents the specific ionizing electron path length li of an electron having an energy of eVi. The results were applied to examine the characteristics of a cage type ion source.