Electrochemical Reactions of Ionic Liquid in Vacuum and Their Influence on Ion-Beam Production by Electrospray
Electrochemical Reactions of Ionic Liquid in Vacuum and Their Influence on Ion-Beam Production by Electrospray
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真空中离子液体的电化学反应及其对电喷雾产生离子束的影响
DOI：
10.1149/1945-7111/abcb3f
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发表时间：
2020
影响因子：
3.9
通讯作者：
Yukio Fujiwara
中科院分区：
文献类型：
--
作者：
松家祐太郎;岡田麻衣子;杉本岩雄;矢野和義;Yukio Fujiwara and Naoaki Saito;Yukio Fujiwara and Naoaki Saito;Yukio Fujiwara
金属与离子液体界面的电化学反应在离子液体离子源中具有重要的实用价值，它可以在真空中通过电喷雾产生负离子束和正离子束。这是因为离子束生产中涉及的电化学反应可能会导致发射器退化，从而导致束流不稳定。在这里，我们研究了用离子液体润湿的钨针产生离子束。我们还使用四极质谱计研究了离子液体在真空中钨电极上的电化学反应，这使得我们能够测量电化学反应生成的挥发性产物。测试了两种离子液体：丙基硝酸铵(PAN)和1-乙基-3-甲基咪唑双(三氟甲磺酰基)酰胺([EMIM][TFSA])，前者是质子型和亲水性的，后者是非质子型和疏水性的。束流测量表明，每种离子液体都能连续产生含有大团簇离子的负离子束。PAN的电化学测试表明，挥发性产物是通过电化学氧化和还原形成的，从而表明PAN的离子束可以在负离子和正离子模式下连续产生。与[EMIM][TFSA]的实验表明，[EMIM]+和[TFSA]−都发生了电化学还原，从而形成挥发性产物，表明这种反应使其能够连续产生负离子束。
Electrochemical reactions at interfaces between metal and ionic liquid are of great practical importance in ionic liquid ion sources, which can produce negative and positive ion beams by electrospray in vacuum. This is because electrochemical reactions involved in ion beam production can cause emitter degradation, leading to beam instabilities. Here we investigate ion beam production using a tungsten needle wetted with ionic liquid. We also investigate electrochemical reactions of ionic liquid at tungsten electrodes in vacuum with a quadrupole mass spectrometer, which allows us to measure volatile products formed via electrochemical reactions. Two types of ionic liquids were tested: propylammonium nitrate (PAN), which is protic and hydrophilic, and 1-ethyl-3-methyl imidazolium bis (trifluoromethanesulfonyl) amide ([EMIM][TFSA]), which is aprotic and hydrophobic. Beam measurements show that a negative ion beam containing large cluster ions can be produced continuously using each ionic liquid. Electrochemical measurements with PAN show that volatile products are formed via electrochemical oxidation and reduction, thereby indicating that ion beams of PAN can be produced continuously in both negative and positive ion modes. Experiments with [EMIM][TFSA] show that the electrochemical reductions of both [EMIM]+ and [TFSA]− occur and thus form volatile products, indicating that such reactions enable its continuous negative ion beam production.