Mass spectra of Fe(CO) 5 using fourier transform mass spectrometry (FTMS) and laser induced thermal desorption FTMS with electron ionization, charge exchange, and proton transfer

Abstract

Fourier transform mass spectrometry is used with chemical ionization to observe iron pentacarbonyl molecules in an ultra-high vacuum system. Mass spectra are obtained from molecules desorbed from a cold Pd(111) surface using laser-induced thermal desorption (LITD) and directly from Fe(CO) 5 vapors. A variety of ions are formed when using 70 eV electrons, including some molecular ion. Charge exchange using Ar + and Xe + produces fewer fragment peaks but no molecular ion. Very little fragmentation occurs to the organometallic when using CH 5 + for proton-transfer reactions. The proton transfer-LITD spectrum does, however, show an unexpected, nonprotonated iron tricarbonyl cation, presumably due to desorption of a surface-activated species.