The temperature dependence of electronic absorption is reported for quantum-sized monolayer protected gold clusters. The investigations carried out on Au25L18 (L= SC6H13) and Au38L24 (L= SC2H4Ph) clusters show discrete absorption bands in the visible and near infrared region at room temperature. The measurements on quantum-sized MPCs have shown three distinct features with a decrease in temperature: (i) the optical absorption peaks became sharper with the appearance of vibronic structure, (ii) the absorption maximum is shifted to higher energies, and (iii) the oscillator strengths of transitions have increased. In contrast, smaller temperature dependence of absorption is observed for plasmonic gold nanoparticles. The results of the shift in band gaps are analyzed by incorporating electron-phonon interactions using the O'Donnel and Chen model. For further comparison temperature dependent optical absorption for Au25 GS18 and Au144 will be presented.

Unique optical transitions in monolayer-protected gold clusters

243rd National Meeting (2012)

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