The kinetic-energy distribution of ${\mathrm{Ag}}^{+}$ ions ejected from a roughened silver surface irradiated with p-polarized laser light at 532 and 355 nm shows two prominent peaks: thermal ${\mathrm{Ag}}^{+}$ ions in the range of 0 to 0.5 eV and ${\mathrm{Ag}}^{+}$ ions with a mean kinetic energy of ∼3.6 eV (2 eV full width at half maximum). Irradiation with 266-nm light shows only the thermal peak. The dependence of the 3.6-eV peak on surface roughness, light polarization, and wavelength implicates a coupling to surface plasmons (SP’s); the SP energy for Ag is also ∼3.7 eV.

• Received 8 September 1992

DOI:https://doi.org/10.1103/PhysRevB.47.9967