The Mn 2+ impurity luminescence decay of Mn 2+ -doped ZnS nanoparticles has been clearly distinguished from ZnS host emission decay by measuring transient absorption and emission kinetic profiles in the picosecond-millisecond time domain. The Mn 2+ luminescence for the doped sample shows two decay components of 0.18 and 2 ms. The fast one is attributed to surface-bound Mn 2+ impurities and the slow one to lattice-bound Mn 2+ impurities. In comparison, the slowest component of ZnS host emission decays within 20 ns. Moreover, excitation-energy transfer from ZnS host to Mn 2+ impurity is also measured to occur on the time scale of 700 ps.

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Both spectra of transient absorption (lambda(max) = 390 nm) and luminescence (lambda(max) = 590 nm) for the (4)T(1) state of Mn(2+) in ZnS nanoparticles shift to long wavelengths by 40 nm and broaden by 1.7 times as the state becomes banded. The (4)T(1) band of capping Mn(2+) in ZnS nanoparticles decays on the time scale of 0.35 mus, which is much shorter than either the decay time of the (4)T(1) state (2000 micros) for lattice-bound isolated Mn(2+) or that (180 micros) for surface-bound isolated Mn(2+) in ZnS nanoparticles.

We present a method to quantitatively measure the thermal conductivity of one-dimensional nanostructures by utilizing scanning thermal wave microscopy (STWM) at a nanoscale spatial resolution. In this paper, we explain the principle for measuring the thermal diffusivity of one-dimensional nanostructures using STWM and the theoretical analysis procedure for quantifying the thermal diffusivity. The SWTM measurement method obtains the thermal conductivity by measuring the thermal diffusivity, which has only a phase lag relative to the distance corresponding to the transferred thermal wave. It is not affected by the thermal contact resistances between the heat source and nanostructure and between the nanostructure and probe. Thus, the heat flux applied to the nanostructure is accurately obtained. The proposed method provides a very simple and quantitative measurement relative to conventional measurement techniques.