日本質量分析学会 第69回質量分析総合討論会会

演題概要

オーラルセッション

第1日 5月19日(水) 15:10~15:30 D会場(Zoom)

静電四重極レンズによるイオンビーム収束を利用した希ガス質量分析計用電子イオン源の高感度化

(1東大院総合文化2東大院理)
o角野浩史1長尾敬介2

Although noble gas isotopes are powerful tracers in geosciences, their extremely low abundances in mineral and rock samples make their analysis quite difficult. We report an attempt of improvement of sensitivity of a noble gas mass spectrometer by installation of a new electron ionization (EI) source (Giese-type source). The Giese-type EI source is equipped with two electrostatic quadrupole lenses. This source has been reported to have up to two orders of magnitude higher sensitivity than conventional Nier-type EI source because of the absence of a beam defining slit to collimate the ion beam and thus high transmission. We designed a Giese-type source to have an adequate resolution to separate 3He+ from HD+ and H3+, to have the source housing volume as small as possible, and to be bankable at up to 300°C to reduce outgas from the source materials. By using the new source, a sufficient mass resolution over 510 essential for 3He/4He analysis has been achieved with an improved sensitivity approximately three times higher than the previous condition. However, total ion transmission is estimated to be about 30%, suggesting further improvement is required to obtain the maximum sensitivity.