Unprecedented intact radical anions, closed shell anions, cluster ions, and traditional cations and radical cations by LIFDI–MS

Abstract

Liquid injection field desorption ionization (LIFDI) proves the extraordinary softness of the ionization process combined with a convenient sample supply under the exclusion of moisture and air. LIFDI–mass spectrometry (MS) is used for organometallic and other seriously air-sensitive compounds forming intact ions without substantial fragmentation. Unprecedented molecular radical anions M–• are presented along with well-known intact M+• radical cations. Furthermore closed shell cations [C]+ and adduct ions like [M + H]+ or [M + Alkali]+ are gently transferred from the solid emitter surface into the gas phase. Anions [A]– or [M − H]– are accessible by LIFDI–MS at medium field strengths. Ion pairs [C]+[A]– are separately detected by positive and negative mode LIFDI–MS, respectively. Here we give an overview of the different ion types accessible by LIFDI–MS. For the first time the field ionization/desorption of solar cell electron acceptor compounds is shown to deliver M–• and M2–• radical ions.