Organometallic liquids provide good properties for ionization detectors. TriMethyl Bismuth
(TMBi) has been proposed as a detector medium with charge and Cherenkov photon readout for
Positron Emission Tomography. In this work, we present studies for the handling of TMBi at
different electric fields and under different environmental conditions to find applicable
configurations for the suppression of electrical breakdowns in TMBi at room temperature. A simple
glass cell with two electrodes filled with TMBi was constructed and tested under different
operation conditions. Working at the vapour pressure of TMBi at room temperature of about
40 mbar and electric fields of up to
20 kV/cm
in presence of a small oxygen contamination
we found the formation of a discharge channel in the liquid and a steady increase in the
current. Further reduction of pressure by pumping caused the TMBi to boil and a spontaneous
combustion. Eliminating the oxygen contamination led the TMBi under the same condition to only
decompose. When operating the setup under an argon atmosphere of 1 bar we did not observe
breakdowns of the electrical potential up to field strengths of 20 kV/cm. Still, in
presence of a small oxygen contamination fluctuating currents in the nA range were observed, but
no decomposition or combustion. We conclude from our experiments that TMBi at room temperature in
a pure argon atmosphere of 1 bar remains stable against electrical breakdown at least up to
electric field strengths of 20 kV/cm, presumably because the formation of gaseous TMBi was
prevented.