UV-laser induced adsorption site changes of CO adsorbed at palladium aggregates will be reported using laser light of lambda = 355 nm. The aggregates with an average size of 100 atoms/island have been deposited on an epitaxial Al2O3/ NiAl(1 1 0) film. As is apparent from IR and temperature programmed desorption spectroscopy (TPD) laser induced migration occurs. It necessitates the presence of adsorbate state density fluctuations. The observation is interpreted as being due to a collective process involving long range dynamical coupling of CO molecules which causes lateral displacements within areas of elevated local adsorbate densities. (C) 2002 Elsevier Science B.V. All rights reserved.