{"title":"Positively Charged Water Microdroplets Ionize Surrounding Gas Molecules","authors":"Yuanyi He, Yifan Meng and Richard N. Zare*, ","doi":"10.1021/jasms.5c00178","DOIUrl":null,"url":null,"abstract":"<p >In electrospray ionization, a liquid solution is passed through a narrow capillary held at high voltage─typically +1 to +5 kV for generating positively charged microdroplets or −1 to −5 kV for negatively charged ones. It has recently been claimed that only negatively charged microdroplets can ionize surrounding gases, whereas positively charged microdroplets cannot. In contrast, we present multiple lines of evidence showing that positively charged water microdroplets are indeed capable of ionizing neutral molecules in their vicinity. Using stabilized nanoelectrospray of deionized water and high-resolution mass spectrometry, we detected ionization products of various neutral species, including oxygen, toluene, and other organic vapors. These results indicate that like their negatively charged counterparts, positively charged microdroplets can induce gas-phase ionization involving the loss of an electron from a neutral precursor, likely facilitated by the intense electric field at the microdroplet water–gas interface.</p>","PeriodicalId":672,"journal":{"name":"Journal of the American Society for Mass Spectrometry","volume":"36 9","pages":"1856–1859"},"PeriodicalIF":2.7000,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of the American Society for Mass Spectrometry","FirstCategoryId":"92","ListUrlMain":"https://pubs.acs.org/doi/10.1021/jasms.5c00178","RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"BIOCHEMICAL RESEARCH METHODS","Score":null,"Total":0}
引用次数: 0
Abstract
In electrospray ionization, a liquid solution is passed through a narrow capillary held at high voltage─typically +1 to +5 kV for generating positively charged microdroplets or −1 to −5 kV for negatively charged ones. It has recently been claimed that only negatively charged microdroplets can ionize surrounding gases, whereas positively charged microdroplets cannot. In contrast, we present multiple lines of evidence showing that positively charged water microdroplets are indeed capable of ionizing neutral molecules in their vicinity. Using stabilized nanoelectrospray of deionized water and high-resolution mass spectrometry, we detected ionization products of various neutral species, including oxygen, toluene, and other organic vapors. These results indicate that like their negatively charged counterparts, positively charged microdroplets can induce gas-phase ionization involving the loss of an electron from a neutral precursor, likely facilitated by the intense electric field at the microdroplet water–gas interface.
期刊介绍:
The Journal of the American Society for Mass Spectrometry presents research papers covering all aspects of mass spectrometry, incorporating coverage of fields of scientific inquiry in which mass spectrometry can play a role.
Comprehensive in scope, the journal publishes papers on both fundamentals and applications of mass spectrometry. Fundamental subjects include instrumentation principles, design, and demonstration, structures and chemical properties of gas-phase ions, studies of thermodynamic properties, ion spectroscopy, chemical kinetics, mechanisms of ionization, theories of ion fragmentation, cluster ions, and potential energy surfaces. In addition to full papers, the journal offers Communications, Application Notes, and Accounts and Perspectives