Effect of Silver Alloying on the Vibrational Dynamics of Rod-Shaped Gold Nanoclusters

Key Words:ULTRAFAST RELAXATION DYNAMICS; ACOUSTIC VIBRATIONS; OPTICAL-PROPERTIES; PHOTOLUMINESCENCE; SUPERATOMS; EXCITATION; PHONON; MODES; AU-25; METAL

Abstract:Doping and alloying are effective strategies to improvethe performanceof metal nanoclusters, including photoluminescence and catalysis.The effect of doping on the electronic properties has been intensivelyinvestigated by experimental and theoretical methods, while the effectof foreign atoms on the mechanical properties of metal nanoclustersremains largely unknown. Here, we investigated the effect of silveralloying on the mechanical properties of rod-shaped gold nanoclustersby comparing the coherent vibrational dynamics of rod-shaped Au-25 and Ag x Au25-x (x & LE; 13). In both nanoclusters,we observed significant coherent vibrations in their transient absorptiondynamics. The coherent vibrations exhibit a frequency of 0.9 THz and0.65 THz for Au-25 and Ag x Au25-x (x & LE; 13),respectively, which are assigned to extension vibration modes of tworods. A detailed analysis of the coherent vibration indicates thatthe amplitude of the excited-state absorption is modulated in thesetwo NCs. These results provide new insights into the photophysicsof alloy metal nanoclusters.

Volume:127

Issue:28

Translation or Not:no