Effect of emissivity on ultrafast luminescence spectra in silver

The effect of emissivity on the ultrafast luminescence spectrum was studied for bulk silver having surfaces with varying grades of roughnesses by using the femtosecond upconversion technique in the infrared region of 0.3–1.0 eV under excitation by 130 fs pulses at 1.19 eV. In addition, the absorptivity spectra were measured by the calorimetric method in the same energy range. As the roughnesses increase, the intensity of the time-resolved luminescence at 0.9 eV at 0 ps increases for three orders of magnitude proportional to the square of the absorptivity, indicating that the luminescence intensity is proportional to the product of absorptivity and emissivity. Although the spectral shapes are very different for the surfaces with different roughnesses, we successfully retrieved internal luminescence spectra after correcting for the emissivity spectrum. It is shown that the retrieval process does not require precise knowledge of microscopic surface morphology.