1P-22 PDF
真空エレクトロスプレーを用いた二次イオン質量分析（ＳＩＭＳ）用イオン液体ビーム源の開発
To develop a vacuum-electrospray beam source for SIMS, we studied the beam characteristics generated by vacuum electrospray of ionic liquids. We electrosprayed the ionic liquid at gas pressures of 10-5 Pa and measured the transient response of a beam current. Transient response analysis enabled us to study m/z distribution of charged species in the beam, thereby showing that m/z values of EMI-TFSA charged droplets were smaller than those of DEME-TFSA. We also confirmed that the m/z values of EMI-TFSA charged droplets diminished with decreasing flow rate. Also, we demonstrated that a stable target current exceeding 30 nA were continuously generated even at a low flow rate of 3 nL/min. On the basis of the obtained m/z value of 7.9*104 at 3 nL/min, the average mass and charge number were estimated to be about 6.1*106 u and 77, respectively. The diameter of the corresponding droplet was estimated to be about 23 nm.