DUAL TIME-OF-FLIGHT PHOTOELECTRON PHOTOION SPECTROMETRY ON A MAGNETICBOTTLE MOLECULAR-BEAM APPARATUS

A supersonic molecular beam experiment including a standard ''magnetic bottle'' TOF photoelectron spectrometer and a TOF ion mass spectromet er has been constructed with the goal of performing MPI studies of coo led molecules and clusters. The supersonic beam characteristics have b een tested by using several pure or mixed rare-gas expansions. A rotat ional temperature of about 0.5 K was measured from the rotational cont ours of the S1 <-- S0 transition of aniline, demonstrating the qualiti es of the molecular beam in the interaction region. The capability of the apparatus to form van der Waals clusters and to mass analyze them was checked by performing (1 + 1) REMPI on fluorostyrene-(Ar)n and ani line-(Ar)n clusters formed in a helium/argon mixture expansion. The se nsitivity of the photoelectron detection was measured by recording the photoelectron spectrum of a pure xenon expansion via a (3 + 2) photon ionization process.