Ion production by positron-molecule resonances

We have recently discovered that positrons form long-lived resonances with large molecules. We present a study of the positive ions that are produced when the positrons annihilate with an electron in such a resonance for the case of alkane molecules (${\mathrm{C}}_{\mathrm{n}}$ ${\mathrm{H}}_{2\mathrm{n}+2\mathrm{}}$). This method of ion production is qualitatively different than those conventionally used and may be useful in the chemical analysis of unknown molecular species by mass spectrometry.