Dynamics of Field-Induced Droplet Ionization: Time-Resolved Studies of Distortion, Jetting, and Progeny Formation from Charged and Neutral Methanol Droplets Exposed to Strong Electric Fields

• DOI: 10.1021/jp0450540
• Publication Date: 2005-04-21T04:39:47Z
• Authors: Ronald L. Grimm; J. L. Beauchamp
• Keywords: Time Factors; Models, Chemical; Methanol; Electric Conductivity; Electrochemistry; 530; 01 natural sciences; 0104 chemical sciences

We recently reported that strong electric fields may be employed to directly extract positive and negative ions for mass analysis, including intact proteins, from neutral droplets. The present study investigates the dynamics of this process using switched high enable time-resolved studies droplet distortion, Taylor cone formation, charged progeny extraction 225 μm methanol After a specific time in field, flashlamp is triggered record distortions shadow photography. At critical field strength Ec0 corresponding limit, droplets exhibit prolate elongation along axis forming symmetric cone-jets negatively droplets, approximately 10 diameter. This termed field-induced ionization (FIDI). Because scale FIDI related frequency shape oscillations occur below models field-dependent oscillation become an important predictor jet formation. Droplets with net charge q distort into asymmetric tear shapes emit single at Ecq less than Ec0. measured decrease stream indicates total loss can greater original on droplet, resulting oppositely Interestingly, above Ec0, sequentially same polarity as followed by reverse emitted opposite direction. For both increasing decreases form jets combination higher-than-critical has compound effect accelerating implications our results FIDI-mass spectrometry on-demand ion sampling are discussed.