SURFACE-PLASMON EJECTION OF AG+ IONS FROM LASER IRRADIATION OF A ROUGHENED SILVER SURFACE

The kinetic-energy distribution of Ag+ ions ejected from a roughened s ilver surface irradiated with p-polarized laser light at 532 and 355 n m shows two prominent peaks: thermal Ag+ ions in the range of 0 to 0.5 eV and Ag+ ions with a mean kinetic energy of approximately 3.6 eV (2 eV full width at half maximum). Irradiation with 266-nm light shows o nly the thermal peak. The dependence of the 3.6-eV peak on surface rou ghness, light polarization, and wavelength implicates a coupling to su rface plasmons (SP's); the SP energy for Ag is also approximately 3.7 eV.