Dual time-of-flight photoelectron-photoion spectrometry on a magnetic bottle-molecular beam apparatus

A supersonic molecular beam experiment including a standard "magnetic bottle" TOF photoelectron spectrometer and a TOF ion mass spectrometer has been constructed with the goal of performing MPI studies of cooled molecules and clusters. The supersonic beam characteristics have been tested by using several pure or mixed rare-gas expansions. A rotational temperature of about 0.5 K was measured from the rotational contours of the S1 <-- S0 transition of aniline, demonstrating the qualities 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 aniline-(Ar)n clusters formed in a helium/argon mixture expansion. The sensitivity of the photoelectron detection was measured by recording the photoelectron spectrum of a pure xenon expansion via a (3 + 2) photon ionization process.