The femtosecond laser ablation of a gold target in aqueous solutions has been used to produce colloidal Au nanoparticles with controlled surface chemistry. A detailed chemical analysis showed that the formed were partially oxidized by oxygen present solution. hydroxylation these Au−O compounds, followed proton loss give Au−O-, resulted negative charging nanoparticles. partial oxidation nanoparticle enhances its reactivity and consequently strong impact on growth. In particular, reacted...

The diffusion and coalescence of metal nanoparticles play important roles in many phenomena. Here, we offer a new integrated overview the main factors that control nanoparticle process. Three are considered our description process: across surface, their physical thermodynamic properties, mechanism coalescence. We demonstrate liquid-like properties surface layers an essential role this present experimental evidence for opinion, based on high-resolution electron microscopic analysis several...

Femtosecond laser radiation has been used to ablate a gold target in aqueous β-cyclodextrin (CD) solutions produce stable nanoparticle colloids with extremely small size (2 2.4 nm) and dispersion (1 1.5 nm). On the basis of XPS ζ-potential measurements, we propose model involving chemical interactions between CDs. The includes both hydrophobic interaction Au0 interior cavity CD hydrogen bonding O- groups on partially oxidized surface −OH

The interaction between multiwalled carbon nanotubes (MWCNTs) and aqueous poly(diallyl dimethylammonium) chloride (PDDA) was studied by X-ray photoelectron (XPS) photoacoustic Fourier transform infrared (PA-FTIR) spectroscopies. We have found that the mild sonication of MWCNTs in PDDA results a significant improvement CNT dispersibility greatly enhances their adhesion to Au Si substrates. MWCNT-PDDA is due presence an unsaturated contaminant chain, as confirmed both XPS PA-FTIR, which enters...

3D Pt nanoflowers, which are composed of numerous single-crystal nanowires, successfully synthesized by a facile chemical procedure, at room temperature, without surfactant or template. The nanoflowers adhere to carbon paper, exhibiting an enlarged electroactive surface area comparable that commercial Pt/C electrode. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2089/2008/c1408_s.pdf from author. Please note: publisher not...

We use high purity Fe oxide nanoparticles to confirm the 2p X-ray photoemission peak attributions made in our previous study of and initial stage their oxidation. To accomplish this, we have found it necessary consider spectral contributions ligand field Fe−O crystal structure, crystalline disorder at nanoparticle surface, Russell−Saunders broadening FeIII components spectra.

Of several samples of polyvinyl pyrrolidone (PVP) used to coat and stabilize freshly manufactured aqueous dispersions silver nanoparticles, one batch gave anomalous results: the dispersion maintained continued stability, even on extensive dilution. Our efforts understand this desirable feature concluded that generally spectral method PVP purity verification, Fourier transform infrared (FTIR) spectroscopy, was incapable answering our inquiry. This led employment other methods, including X-ray...

C 1s XPS spectra of various highly oriented pyrolytic graphite (HOPG) surfaces, untreated, as well those treated by keV Ar+ beam bombardment and low-energy O2, N2, Ar, H2O plasmas, have been systematically studied comparing two peak-fitting procedures. These procedures treat the spectrum either (1) overlap several symmetric component peaks or (2) a single asymmetric peak. The results indicate that, in case HOPG, asymmetry parameter defining peak is directly related to extent damage alternant...

We have carried out the functionalization of multiwalled carbon nanotubes (MWCNTs) via π−π interaction with benzyl mercaptan. The presence noncovalently bonded mercaptan was demonstrated by X-ray photoelectron spectroscopy, which revealed spectral changes indicating its CNTs. subsequent bonding thiol groups to both evaporated and chemically reduced Pt nanoparticles formation strong Pt−S bonds in 4f S 2p spectra. High-resolution transmission electron microscopy used confirm nanoparticle...

Sonication has been widely used in the dispersal of carbon nanotubes (CNTs) various liquids as well their functionalization aqueous acids. Here, for first time, we study sonication multiwalled CNTs (MWCNTs) deionized water. Our results indicate an improvement MWCNTs increase adhesive interaction with Au substrates. Field emission scanning electron and high-resolution transmission microscopies X-ray photoelectron, photoacoustic Fourier transform IR, Raman spectroscopies have shown this to be...

A highly stable crystalline S-passivated InP(100) surface has been obtained by a simple wet chemical process, using illumination and heated (NH4)2S solution. Low-energy electron diffraction studies show (1×1) pattern, which persists even after 3 days of exposure to the atmosphere. High-resolution photoemission that is terminated with monolayer sulfur, forms bridge bonds only indium. The P 2p core level identical vacuum-cleaved InP surface. possible structural model presented.

The permeation of water has been measured through polyimide film over a range thicknesses, temperatures, and relative humidities. concentration absorbed was found to depend on the humidity not temperature or sample thickness, reaching maximum one molecule per repeat unit at 100% rh. This is discussed in terms adsorption, with supporting data surface-layer contribution permeability coefficient.

Superhydrophobic (SH) surfaces generally refer to those having a static water contact angle larger than 150° and slide less 10°, when both the surface droplet are at room temperature.

The air oxidation kinetics of low coverages ∼5nm Si nanoparticles, deposited by pulsed excimer laser ablation (KrF, 248 nm) in He, have been characterized x-ray photoelectron spectroscopy. A simple model, based on the evolution 2p spectral components during oxidation, has developed to determine nanoparticle oxide thickness. It is found that short-term thickness greater, and long-term room-temperature oxidization rate these nanoparticles less, than those reported for bulk a-Si c-Si. results...

Pt nanowire−carbon nanotube heteronanostructures were formed from single-crystal platinum nanowires, grown, in situ, on multiwalled carbon nanotubes, using a "green" chemical procedure at room temperature. The surface density of NWs MWCNTs can be effectively modulated by controlling the CNT weight ratio to precursor.