LIGHT-EMISSION FROM IMPACTS OF ENERGETIC PROTEINS ON SURFACES AND A LIGHT-EMISSION DETECTOR FOR MASS-SPECTROMETRY

Photon emission from impacts of electrosprayed protein ions onto Au, Ta, Si and CsI surfaces was studied. Mass spectra of insulin, lysozyme and apo-myoglobin were acquired by scanning the mass-to-charge ratio of a quadrupole mass filter while simultaneously detecting the photon and secondary electron signals. These spectra were very similar, but spectra acquired using photons displayed a somewhat better signal-to-noise ratio. The estimated photon emission yield is of the order of 0.5 photons per ion impact, a quantity which is not strongly dependent on target material. A higher yield of photons per incident ion was observed for apo-myoglobin and lysozyme ions than for insulin ions.