Observation of microsecond luminescence while studying two DNA-stabilized silver nanoclusters emitting in the 800-900 nm range

• Published in: Physical chemistry chemical physics : PCCP 2021-06, Vol.23 (24), p.13483-13489
• Main Authors: Rück, Vanessa, Cerretani, Cecilia, Neac u, Vlad A, Liisberg, Mikkel B, Vosch, Tom
• Format: Article
• Language: English
• Subjects: Absorption spectra; Decay; Emission analysis; Emitters; Fluorescence; Nanoclusters
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/d1cp01731d

We investigated two DNA-stabilized silver nanoclusters (DNA-AgNCs) that show multiple absorption features in the visible region, and emit around 811 nm (DNA811-AgNC) and 841 nm (DNA841-AgNC). Both DNA-AgNCs have large Stokes shifts and can be efficiently excited with red light. A comparison with the commercially available Atto740 yielded fluorescence quantum yields in the same order of magnitude, but a higher photon output above 800 nm since both DNA-AgNCs are more red-shifted. The study of both DNA-AgNCs also revealed previously unobserved photophysical behavior for this class of emitters. The fluorescence quantum yield and decay time of DNA841-AgNC can be increased upon consecutive heating/cooling cycles. DNA811-AgNC has an additional absorption band around 470 nm, which is parallel in orientation to the lowest energy transition at 640 nm. Furthermore, we observed for the first time a DNA-AgNC population (as part of the DNA811-AgNC sample) with green and near-infrared emissive states with nanosecond and microsecond decay times, respectively. A similar dual emissive DNA-AgNC stabilized by a different 10-base DNA strand is also reported in the manuscript. These two examples highlight the need to investigate the presence of red-shifted microsecond emission for this class of emitters. Photophysical characterization of two DNA-AgNCs emitting in the 800-900 nm range and the observation of microsecond luminescence.