Hybrid samples based on ZnO colloidal nanocrystals (NCs) deposited on AlGaN/GaN quantum well (QW) structures with different top barrier thickness d = 3, 6 and 9 nm are studied by time-resolved photoluminescence. Thermal behavior of the QW exciton lifetime in the hybrids and in the bare QW structures has been compared and it has been found that the QW exciton recombination rate increases in the ...

A laser spectroscopic method was developed to directly observe the lifetimes of individual states in metastable antiprotonic helium atoms ( p̄ He). Collisional effects with surrounding helium atoms were studied in cryogenic gas targets at pressures between 0.1 and 9.0 bars and at temperatures between 5.5 and 7.0 K. The metastable state (n ,l )5(39,35) showed a lifetime of 1.5 ms, regardless of d...

Ultrafast differential transmission measurements on a series of InN epilayers, grown by molecular beam epitaxy, have been employed to determine the carrier lifetimes and to probe the carrier recombination dynamics at room temperature. Differential transmission spectra reveal a peak energy of B0.7 eV on these samples, supporting the existence of the narrow band gap of InN. In addition, we observ...

Radiative lifetimes have been measured for two excited levels of Ce IV using the time-resolved laser-induced fluorescence technique. Ce3+ ions were produced in a laser-induced plasma. In the measurements, a suitable magnetic field was applied to reduce the recombination between electrons and the ions and thus the background light from the recombination, and special care was exercised to avoid f...

Silver nanoparticle aggregates have been shown to support very large enhancements of fluorescence intensity from organic dye molecules coupled with an extreme reduction in observed fluorescence lifetimes. Here we show that for the same type of aggregates, similar enhancement factors (~75× in intensity and ~3400× in lifetime compared to the native radiative lifetime) are observed for a ruthenium...

Nanocrystal quantum dots are attractive materials for applications as nanoscale light sources. One impediment to these applications is fluctuations of single-dot emission intensity, known as blinking. Recent progress in colloidal synthesis has produced nonblinking nanocrystals; however, the physics underlying blinking suppression remains unclear. Here we find that ultra-thick-shell CdSe/CdS nan...

The v=1-->0 radiative lifetime of NH(X(3)Sigma(-),v=1,N=0) is determined to be tau_(rad,exp.)=37.0+/-0.5_(stat)+2.0/-0.8_(syst) ms, corresponding to a transition dipole moment of |mu_(10)|=0.0540_(-0.0018)(+0.0009) D. To achieve sufficiently long observation times, NH(X;{3}Sigma;{-},v=1) radicals are magnetically trapped using helium buffer-gas loading. The rate constant for background helium-i...

In an effort to elucidate the spin (rather than charge) degrees of freedom in colloidal semiconductor nanocrystal quantum dots, we report on a series of static and time-resolved photoluminescence measurements of colloidal CdSe quantum dots in ultrahigh magnetic fields up to 45 T. At low temperatures (1.5-40 K), the steady-state photoluminescence (PL) develops a high degree of circular polarizat...

Membranes of living cells are characterized by laser-assisted fluorescence microscopy, in particular a combination of microspectrofluorometry, total internal reflection fluorescence microscopy (TIRFM), fluorescence lifetime imaging (FLIM) and Forster resonance energy transfer (FRET) spectroscopy. The generalized polarization (GP, characterizing a spectral shift which depends on the phase of mem...

The photophysical properties of Pt(II) meso-tetrakis(4-N-methylpyridyl)porphyrin (PtTMPyP4) have been investigated in the presence of purine mononucleotides using emission and transient UV/visible/near-IR spectroscopy. While both adenosine 5'-monophosphate (AMP) and guanosine 5'-monophosphate (GMP) form 1:1 and 1:2 complexes with PtTMPyP4, the effect on the triplet lifetime is different. With A...