文摘
Nanoclusters of dicyanocuprate (I) ions doped in potassium chloride crystals have been studied. Several emission bands are observed in this system and each emission band can be tuned by site-selective spectroscopy. These bands are assigned to different [Cu(CN)2]− luminescent nanoclusters in the host lattice. The Cu+ ions substitute for K+ ions in the lattice and the CN− ions substitute for Cl− ions in the host with dimer and trimer nanoclusters bonded together by CN− bridges. This is unlike KAg(CN)2 or KAu(CN)2 substituted in a KCl lattice, in which Ag−Ag or Au−Au bonding directly occurs. Ab initio calculations show that the LUMO is a bonding MO while the HOMO is antibonding. Extended Hckel calculations indicate the formation of the LUMO excited-state well is deeper than the ground-state HOMO potential well and with a shorter internuclear separation characteristic of exciplex behavior. Time-resolved luminescence measuremence at room temperature and 78 K demonstrate that, upon pulsed excitation, energy transfer occurs between the dimer and trimer nanoclusters. We conclude that the presence of different luminescent Cu(CN)2− nanoclusters in different environments results in tunability over a wide wavelength range.