Volume 78, Number 5, June 2007
Article Number 56003
Number of page(s) 6
Section Condensed Matter: Structural, Mechanical and Thermal Properties
Published online 21 May 2007
EPL, 78 (2007) 56003
DOI: 10.1209/0295-5075/78/56003

Reversible buckling in monolayer of gold nanoparticles on water surface

M. K. Bera1, 2, M. K. Sanyal1, S. Pal1, J. Daillant3, A. Datta1, G. U. Kulkarni4, D. Luzet3 and O. Konovalov5

1  Surface Physics Division, Saha Institute of Nuclear Physics - 1/AF, Bidhannagar, Kolkata 700064, India
2  S. N. Bose National Centre for Basic Sciences - JD-Block, Sec-3, Salt Lake, Kolkata-700098, India
3  LIONS, Service de Chimie Moléculaire, CEA Saclay - F-91191 Gif-sur-Yvette Cedex, France
4  Jawaharlal Nehru Center for Advanced Scientific Research - Jakkur, Bangalore - 560064, India
5  European Synchrotron Radiation Facility, Beamline ID10B - P.O. Box 220, F-38043 Grenoble, France

received 7 April 2007; accepted in final form 23 April 2007; published June 2007
published online 21 May 2007

Formation of condensed films of nanoparticles having small ratio of metal-core-diameter to organic-shell-thickness is desired for several applications in nanotechnology. We report here results of a X-ray scattering study carried out to understand structure and morphology of monolayer of such nanoparticles having gold-core and thiol-shell directly on the water surface before the monolayer undergoes a continuous transition to a bilayer. Our results demonstrate buckling of the monolayer over a large surface pressure range (1 to 15 mN/m). The buckled state exhibits reversibility on decompression and can be annealed with temperature. We also show that condensed monolayer films of nanoparticles can be formed by annealing the buckled monolayer before transferring to solid substrates.

61.10.Eq - X-ray scattering (including small-angle scattering).
68.18.-g - Langmuir-Blodgett films on liquids.
68.03.-g - Gas-liquid and vacuum-liquid interfaces .

© Europhysics Letters Association 2007