Vacuum electrospray of volatile liquids assisted by infrared laser irradiation.
Vacuum electrospray of volatile liquids assisted by infrared laser irradiation.
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DOI：
10.1002/rcm.6181
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发表时间：
2012-04
期刊：
影响因子：
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通讯作者：
S. Ninomiya;L. Chen;Hiroaki Suzuki;Y. Sakai;K. Hiraoka
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文献类型：
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作者：
S. Ninomiya;L. Chen;Hiroaki Suzuki;Y. Sakai;K. Hiraoka
原理：目前的大型簇光源，如C（60）或氩，使用气相光源，亮度低，不能有效地聚焦到直径大于1微米的光斑尺寸。高亮度大簇离子源的开发对于实现有机物二次离子质谱成像的高分辨率至关重要。方法提出了一种新的高亮度大簇离子源，以及一种在真空条件下产生挥发性液体稳定电喷雾的技术。众所周知，挥发性液体如水的真空电喷雾是极其困难的，因为通过蒸发冷却在真空中引入的液体会冻结。为了避免冻结，用连续波红外激光照射电喷雾发射器的尖端。结果在没有连续激光照射的情况下，水/甲醇溶液的真空电喷雾在泰勒锥形状和电流方面是不稳定的，而连续激光照射产生的水电喷雾是稳定的。即使在真空条件下，用光学显微镜也能清楚地观察到典型的电喷雾模式。通过提高真空压力来抑制放电，利用激光来保持液体状态，可以实现稳定的真空电喷雾。结论：本文首次描述了一种稳定的挥发性液体真空电喷雾的生产方法。这种真空电喷雾技术有望产生一种新型的高亮度大簇离子束源。
RATIONALE Current large cluster sources such as C(60) or argon utilize gas-phase sources which are of low-brightness and cannot be focused efficiently to better than 1 micron diameter spot size. The development of a high-brightness large cluster ion source is of critical importance to achieve high resolution in secondary ion mass spectrometry (SIMS) imaging of organics. METHODS We propose a new high-brightness large cluster ion source, and a technique for producing a stable electrospray of volatile liquids under vacuum. It is known that vacuum electrospray of volatile liquids such as water is extremely difficult because of freezing of the liquids introduced in vacuum by evaporative cooling. To avoid freezing, the tip of the electrospray emitter was irradiated by a continuous wave infrared laser. RESULTS Without continuous laser irradiation the vacuum electrospray of a water/methanol solution was unstable with respect to the shapes of the Taylor cone and current, whereas continuous laser irradiation produced a stable electrospray of water. The typical modes of electrospray were clearly observed with an optical microscope even under vacuum conditions. A stable vacuum electrospray could be achieved by improving the vacuum pressure to suppress electric discharge and by using the laser to maintain the liquid state. CONCLUSIONS This is the first description of the production of a stable vacuum electrospray of volatile liquids such as water. This vacuum electrospray technique can be expected to produce a novel high-brightness large cluster ion beam source.