Spraying Mode Effect on Droplet Formation and Ion Chemistry in Electrosprays

详细信息    查看全文

• 作者：Peter Nemes ; Ioan Marginean ; Akos Vertes
• 刊名：Analytical Chemistry
• 出版年：2007
• 出版时间：April 15, 2007
• 年：2007
• 卷：79
• 期：8
• 页码：3105 - 3116
• 全文大小：7029K
• 年卷期：v.79,no.8(April 15, 2007)
• ISSN：1520-6882

文摘

Depending on the spraying conditions and fluid properties, a variety of electrospray regimes exists. Here weexplore the changes in ion production that accompany thetransitions among the three axial spraying modes, theburst mode, the pulsating Taylor cone mode, and thecone-jet mode. Spray current oscillation and phase Doppler anemometry measurements, fast imaging of theelectrified meniscus, and mass spectrometry are utilizedto study the formation, size, velocity, and chemicalcomposition of droplets produced in the three modes.High-speed images indicate that the primary droplets areproduced by varicose waves and lateral kink instabilitieson the liquid jet emerging from the Taylor cone, whereassecondary droplets are formed by fission. Dramaticchanges in the droplet size distributions result from thevarious production and breakup mechanisms observedat different emitter voltages and liquid flow rates. Wedemonstrate that droplet fission can be facilitated by spacecharge effects along the liquid jet and in the plume.Compared to the other two regimes, a significantly enhanced signal-to-noise ratio, a lower degree of analyteoxidation, and milder fragmentation are observed for thecone-jet mode.