NONTHERMAL PHOTODESORPTION OF N-2 FROM AG(111)

We have measured translational and rotational energy distributions of N-2 molecules following desorption from a Ag(111) surface by infrared (1064 nm) radiation. The observed desorption yields were large even at laser fluences far below that required for laser-induced thermal deso rption. State-resolved laser techniques using coherent VUV radiation s howed that the rotational and translational energy distributions of th e desorbing N-2 molecules are not consistent with the predictions of t he heat diffusion model governing laser-induced surface heating. These results suggest that physisorbed adsorbates can couple directly to th e nascent-phonon distribution or the nascent electron-hole pairs in th e photoexcited substrate without heating of the surface. (C) 1998 Amer ican Institute of Physics. [S0021-9606(98)70542-2]