Nanocrystal particle mobility and quenching of photon emission are reported to be correlated, During a study of photon emission from self-organized arrays of nanocrystals induced by interaction with the tip of a scanning tunneling microscope (STM), a comparison of photon maps with STM images revealed large variations in photon emission efficiency depending on how tightly a nanoparticle is embedded in the hexagonal network. This quenching-mobility correlation is explained in terms of electron relaxation processes involving the nanocrystals' surface phonon modes.