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

European Journal of Mass Spectrometry, Volume 29, Issue 1, Page 5-11, February 2023.
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.