We present measurements of photoluminescence decay dynamics from single colloidal CdSe quantum dots. We find that the decays fluctuate in time with decay rates that correlate with time-averaged emission intensities. Moreover, the decays measured by selecting only those photons collected while the single quantum dot emission intensity was near its maximum yields single-exponential dynamics. We find that the “maximum-intensity” decays are nearly identical across different independently synthesized samples of nearly the same size. The combination of single-exponential kinetics and decays that are reproducible across samples leads us to speculate that it is the radiative lifetime that is measured and that the quantum yield of a single dot near its maximum emission intensity is close to unity. The variations in decay rates with time and their correlation with emission intensity indicate these intensity time trajectories primarily reflect fluctuations in nonradiative relaxation pathways.

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The neutron-deficient gold (Z = 79) isotopes in the vicinity of the neutron midshell N = 104 provide prolific examples of shape coexistence and isomerism at low excitation energy. They can be probed via a number of different experimental techniques. In this study, two new isomeric states with half-lives of 294(7) and 373(9) ns have been observed in the neutron-deficient odd-odd nuclide 178 Au (N = 99) in an experiment at the RITU gas-filled separator at JYFL, Jyväskylä. This result was achieved due to the use of a segmented planar germanium detector with a high efficiency at low energies. By applying the recoil-decay tagging technique, they were assigned to decay to two different long-lived α-decaying states in 178 Au.