Preparation and characterisation of silver quantum dot superlattice using self-assembled monolayers of pentanedithiol

Pethkar, Sushama; Aslam, M.; Mulla, I.S.; Ganeshan, P.; Vijayamohanan, K.

doi:10.1039/b009372f

Cited by 36 publications

(28 citation statements)

References 29 publications

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“…The broadening in the peak as seen from the figure is due to the smaller diameter (∼2.8 nm) of the nanowires formed. In case of Ag-MCM-41 the observed peak position shows a red shift when compared to bare silver nanoparticle which exhibits sharp absorption peak at 390 nm [35]. The nature of Au-MCM-41 absorption spectrum is also similar to that of Au-SiO 2 mesoporous composite reported elsewhere [36].…”

Section: Absorption Spectroscopysupporting

confidence: 58%

“…The electronic charge distribution is delocalized along the direction normal to the well layer. The silica wall barrier thickness is 16Å as calculated from XRD [38], which is sufficiently small to allow the coupling of electrons between adjacent wells that gives rise to new broadening and delocalized quantized states called minibands [35]. Transition of electrons in these minibands gives rise to two emission peaks at 325 and 625 nm for Ag-MCM-41 and at 375 and 675 nm for Au-MCM-41, respectively.…”

Section: Emission Spectroscopymentioning

confidence: 99%

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Synthesis, characterization and optical properties of silver and gold nanowires embedded in mesoporous MCM-41

et al. 2006

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Uniform nanowires of silver and gold inside the channels of MCM-41 were prepared by controlled reduction of their respective metal salts with sodium borohydride (NaBH 4 ). Presence of nanowires of silver and gold in MCM-41 were confirmed by high angle X-ray diffraction (XRD) data (peaks between 2θ = 30 − 60• ) and transmission electron microscopy (TEM) confirmed the diameter of the nanowires. Diameter of nanowires is found to be ∼ 2.8 nm which is coincident with channel diameter of MCM-41. Optical properties of these heterostructured materials Ag-MCM-41 and Au-MCM-41 reveals the presence of surface plasmon absorption peaks of silver and gold respectively, and the shift in the absorption bands are associated to agglomeration of clusters inside the channels. Room temperature photoluminescence spectra exhibits interesting optical properties as observed for direct band gap semiconductors. Non-linear optical properties (NLO) corresponding to second harmonic generation (SHG) values were also recorded for self supported films of these heterostructured materials. Enhanced optical non-linearity was found to be arising from a corresponding increase of local field near the surface plasmon resonance. Further enhancement in SHG was found with poling due to an induction of orientation order.

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Section: Absorption Spectroscopysupporting

confidence: 58%

Section: Emission Spectroscopymentioning

confidence: 99%

Synthesis, characterization and optical properties of silver and gold nanowires embedded in mesoporous MCM-41

et al. 2006

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“…The most common approaches entail chemical bonding (e.g. S-Au), [6][7][8][9][10][11] van der Waals forces involving the stabilisers at the particle surface, [12][13][14][15][16] and electrostatic forces. [17][18][19][20][21] Although tremendous efforts have been devoted to the characterisation of nanoparticle arrays obtained by different assembling methods, systematic studies of the size and nature of the nano-object, deposition time, particle-substrate distance and so forth are somewhat scarce.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical and optical properties of two dimensional electrostatic assembly of Au nanocrystals

et al. 2004

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The spectroscopic and electrochemical properties of two-dimensional electrostatic assembly of Au nanocrystals are examined on poly-L-lysine (pLys) modified gold electrodes. The surface preparation for the nanoparticle deposition involved the selfassembly of a monolayer of 11-mercaptoundecanoic acid on the electrode surface, followed by the electrostatic deposition of pLys from aqueous solution. The polyelectrolyte layer acts as the electrostatic anchor for the Au particles. Electrostatically stabilised Au particles were prepared by homogeneous reduction in the presence of citrate, yielding monodispersed colloidal suspension with an average diameter of 18 AE 2 nm. After 4 h of deposition, the citrate-stabilised particles reach a maximum surface density of (8.2 AE 0.1) Â 10 10 particles cm À2 , with an average edge-to-edge distance of 25 nm. The particle surface density was estimated from scanning electron micrographs. Kelvin probe measurements were employed for examining changes in surface dipole introduced by the 2D array of nanocrystals. From simple electrostatic arguments, the apparent static dipole moment per particle was estimated of the order of 2700 D. The strong interaction between the nanocrystals and the pLys layer is responsible for the surface charge displacement, leading to changes in the surface dipole of 0.35 eV. These electrostatic interactions also manifest itself by the red shift of the plasmon resonance of the assembly with respect to the aqueous colloidal suspension. Analysis of the spectral broadening was attempted within the framework of the so-called coherent-potential approximation. Finally, electrochemical studies in 1,2-dichloroethane show a large electronic overlap between the nanocrystals and the metal substrate. Results obtained from electrochemical impedance spectroscopy strongly suggest that the electrostatic assembly of nanocrystal behaves like a 2D array of randomly distributed spherical nanoelectrodes.

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“…This characteristic peak is due to the oscillation of conduction band electrons of silver (also known as surface plasmon resonance) [17]. The observed peak position is red shifted as compared with bare silver nanoparticles, which exhibits sharp absorption peak at 390 nm [18]. The position of plasmon absorption band depends on particle size, aspect ratio and diameter of nanowires [19].…”

Section: Resultsmentioning

confidence: 95%

“…The electronic charge distribution is delocalised along the direction normal to the well layer. Silica wall barrier thickness is 16 Å (calculated from XRD) [20], which is sufficiently small to allow the coupling of electrons between adjacent well that gives rise to new broadened and delocalised quantized state called miniband [18]. Transition of electrons in these minibands is observed as two distinct emission peaks at 325 and 625 nm, respectively.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of silver nanowires inside mesoporous MCM-41 host

et al. 2004

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Preparation and characterisation of silver quantum dot superlattice using self-assembled monolayers of pentanedithiol

Cited by 36 publications

References 29 publications

Synthesis, characterization and optical properties of silver and gold nanowires embedded in mesoporous MCM-41

Synthesis, characterization and optical properties of silver and gold nanowires embedded in mesoporous MCM-41

Electrochemical and optical properties of two dimensional electrostatic assembly of Au nanocrystals

Synthesis of silver nanowires inside mesoporous MCM-41 host

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