The dynamics of short pulsed infrared laser-induced desorption of Cesium atoms from porous silica samples has been investigated. We find most probable kinetic energies of 69 +/- 6 meV for desorption laser fluences between 60 and 190 mJ/cm(2), significantly higher compared to those obtained for Cs desorption from plain glass, 40 +/- 2 meV, but lower compared to those observed for Na and Rb desorption from polymeric surfaces, 200 meV. This is explained qualitatively by scattering of the desorbing atoms with the silica nanochannels, thus suggesting different pulsed laser photodesorption processes for atoms embedded in hard porous dielectrics as compared to polymeric thin films. (c) 2006 Elsevier B.V. All rights reserved.