A simple model for understanding the fluorescence behavior of Au25 nanoclusters

Wang, Shuxin; Zhu, Xiuyi; Cao, Tiantian; Zhu, Manzhou

doi:10.1039/c3nr06722j

Cited by 45 publications

(39 citation statements)

References 42 publications

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“…Although some of the fractions were not atomically pure ( n < 15, n > 29) very interestingly these authors reported that, as shown in Table , independently on the size, the molar absorption coefficient is of the order of 10 4 m –1 cm –1 . The molar absorption spectrum of Au 25 (SC 2 H 4 Ph) 18 , reported more recently by Wang et al, confirmed these results …”

Section: Uv/vis Absorption Of Gncssupporting

confidence: 84%

Towards Ultra‐Bright Gold Nanoclusters

et al. 2017

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Fluorescence bioimaging is a non-invasive technique that permits to investigate living organism in real time with high tridimensional resolution. Properly engineered fluorescent (or photoluminescent) nanoparticles promise to surpass conventional fluorescent molecular probes as contrast agent. Photoluminescent semiconductor quantum dots show, for example, enhanced brightness and photostability. Concerns arising from the toxic metal content of quantum dots prompted the search for alternative inorganic nanoparticles with similar properties but less hazardous. Gold is almost unanimously considered to

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Section: Uv/vis Absorption Of Gncssupporting

confidence: 84%

Towards Ultra‐Bright Gold Nanoclusters

et al. 2017

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“…[11][12][13][14] Since the size of metal nanoclusters is close to their Fermi wavelength (<1 nm), they behave like molecules. The fluorescence observed from dendrimer coated AuNCs follows the free electron model and arise from intraband (sp-sp) transitions, which are sensitive to the cluster sizes.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast Relaxation Dynamics of Luminescent Rod-Shaped, Silver-Doped Ag_xAu_25–x Clusters

et al. 2015

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The luminescent ligand protected metal clusters have attracted considerable attentions while the origin of the emission still remains elusive. As recently reported in our previous work, the rod-shaped Au 25 cluster possesses a low photoluminescence quantum yield (QY=0.1%), whereas substituting silver atoms for central gold atom in the rod-shaped Au 25 cluster can drastically enhance the photoluminescence with high quantum yield (QY=40.1%). To explore the enhancement mechanism of fluorescence, femtosecond transient absorption spectroscopy is performed to determine the electronic structure and ultrafast relaxation dynamics of the highly luminescent silver-doped Ag x Au 25-x cluster by comparing the excited state dynamics of doped and un-doped Au 25 rod cluster, it is found that the excited state relaxation in Ag x Au 25-x , is proceeded with an ultrafast (~0.58 ps) internal conversion and a subsequent nuclear relaxation (~20.7 ps) followed by slow (7.4 µs) decay back to the ground state. Meanwhile, the observed nuclear relaxation is much faster in Ag x Au 25-x (~20.7 ps) compared to that in un-doped Au 25 rod (~52 ps). We conclude that it is the central Ag atom which stabilizes the charges on LUMO orbital and enhances the rigidity of Ag x Au 25-x cluster that leads to strong fluorescence.Meanwhile, coherent oscillations around ~ 0.8 THz were observed in both clusters, indicating the symmetry preservation from Au cluster to Ag alloying Au clusters. The present results provide new insights for the structure-related excited state behaviors of luminescent ligand protected Ag alloying Au clusters.

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“…Experimental work by Zhou's group has established that the ligand types protecting the thiolated Au 25 core are important because some ligands can enhance the quantum yield. 29 Moreover, the fluorescence mechanism in a thiolated gold cluster is not clear but there exist some important proposals. 30,31 Regarding chiroptical properties of silver-doped clusters, Jin's group reported that the thiolated Au 18 cluster is nonchiral because there exists a symmetry plane along the dimer motif.…”

Section: Bmentioning

confidence: 99%

Thiolated Au₁₈ cluster: preferred Ag sites for doping, structures, and optical and chiroptical properties

Molina

Tlahuice‐Flores

2016

Phys. Chem. Chem. Phys.

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Recently, the X-ray determined structure of the thiolated Au 18 cluster has been reported. In this communication, we addressed a study of structures and chiroptical properties of thiolated Au 18 cluster doped with up to ten Ag atoms, which have been calculated by Time Dependent Density Functional Theory (TD-DFT). The number of Ag atoms was steadily varied and more stable isomers showed optical and Circular Dichroism (CD) spectra distinct from that found for the parent Au 18 cluster. Doping with more than four Ag atoms results in enhancement of the oscillator strength of the HOMO-LUMO peak and it is expected that this feature can be exploited for photoluminescence applications.The doping of thiolated gold clusters has captured our interest since the first experimental report of Pd doping of the anionic Au 25 (SR) 18 cluster was proposed based on the superior agreement between the calculated CD spectrum featuring a prominent negative peak located at 3.48 eV and the experimental 3.42 eV band. 20Following this line, experimental work devoted to the elucidation of the structure of thiolated Au 18 cluster succeeded recently 21 in providing theoretical groups 22 the opportunity to correct their algorithms used to propose structures and to improve our knowledge in this field. Herein, a DFT 23 study of the X-ray determined structure of thiolated Au 18 cluster produced by doping with up to ten Ag atoms is addressed. 21b The aim of this study is to determinate how the structure, the HOMO-LUMO (HL) gap values, the oscillator strength of the lower energy peak, and the optical and chiroptical properties are affected by Ag doping. A systematic search of lowest-energy isomers was carried out using the PBE functional 24 for the exchange and correlation (XC) terms.

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A simple model for understanding the fluorescence behavior of Au25 nanoclusters

Cited by 45 publications

References 42 publications

Towards Ultra‐Bright Gold Nanoclusters

Towards Ultra‐Bright Gold Nanoclusters

Ultrafast Relaxation Dynamics of Luminescent Rod-Shaped, Silver-Doped Ag_xAu_25–x Clusters

Thiolated Au₁₈ cluster: preferred Ag sites for doping, structures, and optical and chiroptical properties

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A simple model for understanding the fluorescence behavior of Au25 nanoclusters

Cited by 45 publications

References 42 publications

Towards Ultra‐Bright Gold Nanoclusters

Towards Ultra‐Bright Gold Nanoclusters

Ultrafast Relaxation Dynamics of Luminescent Rod-Shaped, Silver-Doped AgxAu25–x Clusters

Thiolated Au18 cluster: preferred Ag sites for doping, structures, and optical and chiroptical properties

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Ultrafast Relaxation Dynamics of Luminescent Rod-Shaped, Silver-Doped Ag_xAu_25–x Clusters

Thiolated Au₁₈ cluster: preferred Ag sites for doping, structures, and optical and chiroptical properties