DEPENDENCE OF THE MULTIPHOTON LUMINESCENCE SPECTRUM OF SINGLE GOLD NANOPARTICLES ON THE REFRACTIVE INDEX OF THE SURROUNDING MEDIUM

摘要

The physical mechanism underlying multiphoton luminescence in gold is still the subject of debate. To obtain a better understanding of the mechanism, experiments that study the luminescence spectra of single particles are necessary. In this study, the multiphoton luminescence spectrum was measured for surrounding media of different refractive indices. The resulting spectra of single gold nanospheres with diameters in the range of a few tens of nanometers were found to be strongly dominated by the absorption peak of the plasmon resonance. This is in agreement with the theory proposed by Boyd et al. (1986). According to Lorenz-Mie Theory, an increase in the refractive index of the surrounding medium results in a redshift of the plasmon resonance spectrum; a corresponding shift in the multiphoton luminescence spectrum has now been found experimentally.