Work function and electron emission from nanocrystalline Pd films

In this paper the results of an investigation of two multi-phase film systems composed of Pd nanocrystals placed in carbonaceous or: fullerenes matrices are presented, The films were obtained by thermal deposition (from two separated sources at the (same time) of an Pd acetate and C(60)/C(70) fullerenes mixture fi:om two separate sources, Structural differences of the films were found by electron diffraction, transmission electron microscopy and Raman spectroscopy. The Raman D- and G-bands belonging to amorphous carbon vibrations and bands that could be attributed to polymerised fullerenes were observed for one kind of film. Raman bands that could be connected to a new fullerene crystalline structure were found for the second kind of film. The Raman spectra also suggest the presence of N(2) molecules superficially bonded to the films. The photoelectric work function of the films was measured under ultra high vacuum conditions with Xe-lamp excitation. The measured value of the work function For both kinds of films was 2.75 eV. The I-U characteristics were also measured for these films. Fowler-Nordheim analysis results were compared with results of photoelectric measurements. (C) 2001 Elsevier Science Ltd. All lights reserved,