Negative gas-phase ion chemistry of GeH4: a quadrupole ion trap study

Gas-phase anion/molecule reactions of germanium hydride were studied by quadrupole ion trap (QIT) mass spectrometry. Under chemical ionization (CI) conditions and with a sample pressure of about 5.0 × 10-5 Torr, clustering reactions proceed up to the formation of Ge5H ion clusters. With increasing cluster size, the most abundant ion species are those with the lowest content of hydrogen. Reaction sequences obtained by ion isolation were determined for primary, secondary and tertiary germane ions, and reaction enthalpies were calculated for reactions of primary ions. Ion/neutral condensation processes followed by single and double dehydrogenation are by far the most important reactions; moreover, isotope scrambling is observed for almost every reactant ion. These results are in good agreement with previously published data and indicate that germane negative ions are quite efficient in formation and growth of ionic clusters, which can be considered suitable precursors of amorphous solid hydrogenated germanium used in the semiconductor field.