Observation of Liquid Water with Ambient SIMS

Abstract

  Secondary ion mass spectrometry (SIMS) is powerful method for obtaining component information from solid samples, such as semiconductor devices and biological tissue. Moreover, SIMS has high surface sensitivity because of the use of a primary ion probe. The keV-energy ion probe is, however, unstable under low vacuum conditions and this makes evaluation of volatile liquid samples difficult. A new SIMS technique that uses an MeV-energy heavy ion probe, called ambient SIMS, enables measuring volatile liquid samples under ambient conditions by high transmission capability of the primary probe. In this study, water in liquid form, which has a relatively high vapor pressure (2,339 Pa at 20℃), was evaluated by ambient SIMS and gave some cluster ions with high intensity. This result suggests that ambient SIMS has significant potential for evaluating both solid and liquid samples with high sensitivity.