[P-PS24_1PO1] 宇宙における物質の形成と進化

[PPS24-P02] イオン誘起微粒子核生成II：水クラスターイオンの自由エネルギー

*日高 宏¹、中井 陽一²、小島 隆夫³、渡部 直樹¹ (1.北海道大学低温科学研究所、2.理化学研究所仁科センター、3.理化学研究所原子物理研究室)

キーワード：星間塵, クラスターイオン, 核生成

Ion-induce nucleation in gas phase is an important mechanism for grain formation in various circumstances. However, the number of works regarding this formation mechanism is very limited. To investigate the elementally processes of ion-nucleation mechanism, we recently developed a new apparatus (See, the presentation by N. Watanabe in this session). Using this apparatus, the cluster ion formation with an ion core mass-selected, which is the first stage of nucleation, can be observed quantitatively. In this presentation, we show the results of experiment on water-cluster ion formation in which free energies with the size of cluster have been determined. The experiment was performed at temperatures in range of 230-400 K with the supersaturation ratio of about 10^-3-10^-2.