12 February 1999 Ž . Chemical Physics Letters 300 1999 633–638 Synthesis of carbon films with controlled nanostructure by separation of neutral clusters in supersonic beams E. Barborini a , P. Piseri a , A. Li Bassi b , A.C. Ferrari b,1 , C.E. Bottani b , P. Milani a, ) a Istituto Nazionale per la Fisica della Materia-Dipartimento di Fisica, UniÕersita’ di Milano, Via Celoria 16, 20133 Milano, Italy b Istituto Nazionale per la Fisica della Materia-CESNEF, Politecnico di Milano, Via Ponzio 34 r 3, 20133 Milano, Italy Received 18 August 1998; in final form 19 October 1998 Abstract Nanostructured carbon thin films have been grown by deposition of cluster beams produced in supersonic expansion. Due to separation effects consisting of an enrichment of heavy clusters in the central portion of the supersonic beam and of light clusters in the peripheral one, films with different nanostructures can be grown by simply intercepting with a substrate different regions of the cluster beam. Raman spectroscopy confirms that the films deposited with different beam portions Ž . have different nanostructures ranging from disordered graphitic fullerene-like precursors to amorphous, with the presence of sp coordination. q 1999 Elsevier Science B.V. All rights reserved. The structural and functional properties of amor- phous carbon films, assembled atom by atom, are largely determined by the kinetic energy of the ions impinging on the substrate during the film growth w x 1–3 . The use of carbon clusters, together with carbon atoms can open new possibilities for the synthesis of materials where the structural and func- tional properties are also determined by the hierar- chical organization of units with dimensions ranging w x from mesoscopic to nanoscopic scale 4,5 . Carbon films with inclusions of fullerene-like structures and nanotube fragments have been pro- ) Corresponding author. E-mail: pmilani@mi.infn.it; fax: q39 02 239 2487 1 Present address: Department of Engineering, University of Cambridge, Cambridge, UK. duced with a filtered cathodic arc apparatus where Ž . the arc occurs in a localized high-pressure 10 torr region. Due to the presence of the inert gas, conden- sation takes place and a beam of monomer ions and clusters is formed and deposited. The incorporation of three-dimensional networks, consisting of buckled planes with fullerene-like features, induces the for- mation of films with very high values of hardness wx and elasticity 6 . Although promising, these experiments suffered from the lack of characterization of the cluster for- mation processes and of cluster mass and kinetic energy distribution. In view of the use of clusters as building blocks of nanostructured thin films, intense and stable beams must be used and a good control on cluster mass and kinetic energies distribution must be achieved. These characteristics can be obtained with the use of beams produced by supersonic expansions. A 0009-2614r99r$ - see front matter q 1999 Elsevier Science B.V. All rights reserved. Ž . PII: S0009-2614 98 01449-3