Theory of the kinetics of luminescence and its temperature dependence for Ag nanoclusters dispersed in a glass host.

We have measured and fitted the kinetics of luminescence of Ag nanoclusters homogeneously dispersed within the bulk of an oxyfluoride glass, with various sample temperatures. The balance equations for the populations of the excited singlet and triplet states of the Ag nanoclusters are proposed and used in this fitting while taking into account inter-system crossing between the singlet and triplet states and their wavelength dependent spontaneous decay to the ground singlet state. The involved energy barriers and rate constants and spontaneous emission cross-sections for the excited singlet and triplet states are evaluated.

Experiment and theoretical modeling of the luminescence of silver nanoclusters dispersed in oxyfluoride glass.

Density functional theory (DFT) and complete active space perturbation theory (CASPT2) have been applied for modeling the configuration, charge, energy states, and spin of luminescent Ag nanoclusters dispersed within the bulk of oxyfluoride glass host. The excitation spectra of luminescence of the Ag nanoclusters have been measured and simulated by means of the DFT and CASPT2. Electron spin resonance spectra have been recorded and suggest diamagnetic state of Ag nanoclusters. The silver nanoclusters have been argued to consist mostly of pairs of Ag(2) (+) dimers, or Ag(4) (2+) tetramers, with different extent of distortion along the tetramer diagonal. The sites for the Ag nanoclusters have been suggested where the pairs of Ag ions substitute onto metal and hole cation sites and are surrounded by fluorine ions within a fluorite-type lattice.

Er(3+)-doped nanoparticles for optical detection of magnetic field.

A bright persistent photoluminescence has been observed in Er(3+)-doped nanoparticles prepared by selective dissolution of bulk oxyfluoride nano-glass-ceramics. A 2 orders of magnitude decrease of intensity of the (4)S(3/2)-->(4)I(15/2) green emission band of Er(3+) in these nanoparticles is observed in magnetic fields up to 50 T. This strong luminescence sensitivity to magnetic field can be used for localization and distant optical detection of magnetic field in nanovolumes with a field-resolution of 0.01 T.

High refractive index chalcogenide glass for photonic crystal applications.

A high refractive index Te-enriched bulk chalcogenide glass Ge(20)As(20)Se(14)Te(46) (n approximately 3.3) has been patterned by ablation using four- and two-beam interference femto-second laser setups operating at 800 nm. The regular arrays of 0.8 mum diameter and more than 0.8 mum depth holes and/or grooves of typical size of 1x1 mm(2) have been written on the surface of the glass in a time-scale of 1 second with 50 femtosecond pulses. The high photosensitivity of this narrow-gap semiconductor glass to the femtosecond irradiation is ascribed to a free electron absorption typical of metals, which is caused by laser-induced heating of the glass.