Molecular ion formation on activated field emitters in atmospheric pressure field desorption mass spectrometry

Abstract

Atmospheric pressure field desorption (APFD) mass spectrometry (MS) has recently been explored as a new contribution to the field of ambient desorption/ionization (ADI). Depending on the selected polarity applied to the field emitter, ionic and polar analytes were demonstrated to deliver positive as well as negative ions. Whereas this recent study solely reported on the formation of even-electron ions of either polarity, the present work on APFD-MS demonstrates the abundant formation of positive molecular ions, M+•, from polycyclic aromatic compounds. Molecular ions were formed on and desorbed from standard 13-µm activated tungsten wire emitters at atmospheric pressure.