High-field operation of submicrometer devices at atmospheric pressure

An array of micrometer-sized field emitter tips was used to produce ions in air or other gases at atmospheric pressure using only low voltages. The ions are produced by the dissociation of gaseous acids or bases in the high electric field near the tips. For example, with formic or acetic acid, ions are formed with the tip at about -50 V; with gaseous Lewis bases or with esters plus water vapor, ions are formed with the tip at either a positive or a negative potential. No ions are detected for alcohols, alkanes, acetone, water vapor, NO/sub 2/, oxygen, nitrogen, or argon. >