scholarly journals Protected Gold Nanoparticles with Thioethers and Amines As Surrogate Ligands

2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
M. Rafiq H. Siddiqui
Keyword(s):  
Gold Nanoparticles ◽  
Variable Temperature ◽  
Size Control ◽  
Analytical Techniques ◽  
High Resolution Electron Microscopy ◽  
Phase Method ◽  
Two Phase ◽  
H Nmr ◽  
Resolution Electron ◽  
Vis Spectroscopy

Dodecyl sulfide, dodecyl amine, and hexylamine were shown to act as surrogate ligands (L) via metastable gold nanoparticles. By collating analytical and spectroscopic data obtained simultaneously, empirical formula Au24L was assigned. These impurity-free nanoparticles obtained in near quantitative yields showing exceptional gold assays (up to 98%Au) were prepared by a modification of the two-phase method. Replacement reactions on the Au24L showed that Au:L ratios may be increased (up to Au55:L (L= (H25C12)2S)) or decreased (Au12:L (L= H2NC12H25and H2NC6H13)) as desired. This work encompassing the role of analytical techniques used, that is, elemental analysis, variable temperature1H NMR, FAB mass spectrometry, UV-Vis spectroscopy, thin film X-ray diffraction, and high-resolution electron microscopy (HREM) has implications in the study of size control, purity, stability, and metal assays of gold nanoparticles.

Synthesis and Microstructural Analysis of Benzylthiol-functionalized Au Nanocrystals

2006 ◽  
Vol 959 ◽  
Author(s):  
Floriana Vitale ◽  
Luciana Mirenghi ◽  
Emanuela Piscopiello ◽  
Maria Lucia Protopapa ◽  
Leander Tapfer ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Au Nanoparticles ◽  
Microstructural Analysis ◽  
High Resolution Electron Microscopy ◽  
Phase Method ◽  
Two Phase ◽  
X Ray ◽  
Resolution Electron ◽  
Phase Liquid ◽  
Ir Emission

ABSTRACTWe report on the synthesis and microstructural and microanalytical analysis of dodecanethiol and benzylthiol-stabilized Au nanoparticles (diameter range between 2 nm and 10 nm). Stable functionalized gold nanoparticles were synthesized by using two different routes: a two-phase liquid-liquid method and a one-phase method. The size, strain, shape and crystalline structure of the nanocrystals were determined by a full-pattern X-ray powder diffraction analysis and high-resolution electron microscopy. The chemical environment of the Au nanocrystals and their interaction with the thiols was investigated by X-ray photoelectron spectroscopy. Photoluminescence spectroscopy measurements show a characteristic IR emission at λ=960 nm of small sized Au nanocrystals (∼3 nm). The origin of this IR emission line seems to be correlated to the Au-S bonding and the size of the nanoparticles.

Recent Applications of High Resolution Electron Microscopy to Crystalline Arrays of Virus Particles

1978 ◽  
Vol 36 (3) ◽  
pp. 470-482 ◽  
Author(s):  
R.W. Horne
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Analytical Techniques ◽  
Staining Technique ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Full Potential ◽  
Virus Particles ◽  
Resolution Electron ◽  
Wide Range

The technique of surrounding virus particles with a neutralised electron dense stain was described at the Fourth International Congress on Electron Microscopy, Berlin 1958 (see Home & Brenner, 1960, p. 625). For many years the negative staining technique in one form or another, has been applied to a wide range of biological materials. However, the full potential of the method has only recently been explored following the development and applications of optical diffraction and computer image analytical techniques to electron micrographs (cf. De Hosier & Klug, 1968; Markham 1968; Crowther et al., 1970; Home & Markham, 1973; Klug & Berger, 1974; Crowther & Klug, 1975). These image processing procedures have allowed a more precise and quantitative approach to be made concerning the interpretation, measurement and reconstruction of repeating features in certain biological systems.

scholarly journals Exploration of the Antimicrobial and Catalytic Properties of Gold Nanoparticles Greenly Synthesized by Cryptolepis buchanani Roem. and Schult Extract

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Kamonpan Wongyai ◽  
Phitchayapak Wintachai ◽  
Rasimate Maungchang ◽  
Parawee Rattanakit
Keyword(s):  
Staphylococcus Aureus ◽  
Gold Nanoparticles ◽  
Analytical Techniques ◽  
Average Diameter ◽  
Face Centered Cubic ◽  
Tem Analysis ◽  
X Ray ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Face Centered

A green, simple, and rapid synthesis of gold nanoparticles using plant extract, Cryptolepis buchanani Roem. and Schult, and their applications are first described in this paper. The formation of gold nanoparticles was visually observed by the appearance of a ruby red color, which was further indicated by an absorption peak at 530 nm in UV-Vis spectroscopy. Optimization of reaction parameters for the gold nanoparticles was also investigated. Various analytical techniques were employed as part of the process of characterizing the resulting gold nanoparticles. Fourier transform infrared (FTIR) analysis revealed that the phenol compounds present in the extract were responsible for gold(III) reduction and stabilization of gold nanoparticles. Transmission electron microscopy (TEM) analysis showed that the gold nanoparticles were spherical in shape with an average diameter of 11 nm. Powder X-ray diffraction (XRD) pattern indicated that the green synthesis approach produced highly crystalline, face-centered cubic gold nanoparticles. Energy-dispersive X-ray spectroscopy (EDS) measurements confirmed the presence of elemental gold in the prepared nanoparticles. The negative zeta potential value of gold nanoparticles was found to be -30.28 mV. The green synthesized gold nanoparticles expressed effective antibacterial activity against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, and Acinetobacter baumannii and exhibited an excellent catalytic property in terms of its reduction ability of methylene blue.

The decagonal quasicrystal formed from an Al–Pd–Mn icosahedral quasicrystal

1995 ◽  
Vol 10 (5) ◽  
pp. 1146-1153 ◽  
Author(s):  
W. Sun ◽  
K. Hiraga
Keyword(s):  
Structural Characteristics ◽  
High Resolution Electron Microscopy ◽  
Icosahedral Quasicrystal ◽  
Two Phase ◽  
Growth Interface ◽  
Decagonal Quasicrystal ◽  
Resolution Electron ◽  
The Matrix ◽  
Solid State Phase Transformation ◽  
Phase Proceeds

We present a detailed investigation on the decagonal quasicrystal (D-phase) formed from an Al-Pd-Mn icosahedral quasicrystal (I-phase) through a solid-state phase transformation, including its formation, compositional and crystallographical relationships with the matrix I-phase, growth mode, and structural characteristics. The as-melt-spun Al70Pd20Mn10 alloy contains only I-phase. By annealing at 800 °C, the D-phase is found to grow cpitaxially from the I-phase to establish a D/I two-phase equilibrium with distinctly different composition between them. The D-phase exhibits a stepped growth interface, which consists of a facet plane, formed by sharing the tenfold plane with a fivefold plane of the matrix I-phase, and some ledges across it. The growth of the D-phase into the I-phase proceeds through lateral movement of the ledges along the tenfold plane. High-resolution electron microscopy reveals that the structure of the D-phase is constructed by an aperiodic arrangement of decagonal atom clusters with definite linkages and long-range quasiperiodic correlation.

Chemical Methods for Synthesizing Gold Nanoparticles

2013 ◽  
Vol 709 ◽  
pp. 19-22
Author(s):  
Juan Zhang ◽  
Jiang Yu ◽  
Nai Yan Zhang ◽  
Pei Liu
Keyword(s):  
Particle Size ◽  
Gold Nanoparticles ◽  
Phase Method ◽  
Chemical Methods ◽  
Two Phase ◽  
Experimental Operation ◽  
Homogeneous Phase ◽  
Detailed Explanation ◽  
Growth Method

For different requirements of particle size of syhthesizing nanoparticles, five practical chemical methods have been introduced including two phase method, homogeneous phase method and seeding growth method and so on. And detailed explanation on the experimental operation methods has been given.

Microstructure and interfaces in TiB2/Ti-46Al-3Cr Alloy Composites

1995 ◽  
Vol 410 ◽  
Author(s):  
Weimin Si ◽  
Michael Dudley ◽  
Pengxing Li ◽  
Renjie Wu
Keyword(s):  
Electron Microscopy ◽  
Titanium Aluminide ◽  
Analytical Electron Microscopy ◽  
Lattice Misfit ◽  
High Resolution Electron Microscopy ◽  
Amorphous Layer ◽  
Two Phase ◽  
Titanium Aluminide Alloy ◽  
Resolution Electron ◽  
Crystallographic Orientation Relationship

ABSTRACTA ternary titanium aluminide alloy, Ti-46Al-3Cr (at%), was discontinuously reinforced with 5 vol% titanium diboride (TiB2), by an in-situ synthesis technique, resulting in a two phase γ(TiAl) (mainly) and α2(Ti3Al) matrix with randomly dispersed TiB2 particle. Interfaces of TiB2-TiAl were investigated by Analytical Electron Microscopy (AEM) and High Resolution Electron Microscopy (HREM). No consistent crystallographic orientation relationship was observed between TiB2 particle and TiAl matrix, and there was no evidence of alloying elements (such as Cr) segregation or interphase formation at the TiB2-TiAl interface. HREM results indicated that no semi-coherent interface between TiB2 and TiAl has been observed. There existed a thin amorphous layer (0.5 to 1.3 nm) at the TiB2-TiAl interface, which may accommodate the large lattice misfit across the interface and enhance the interfacial bonding.

In or on? Location of noble metal particles on zeolite/binder support

1995 ◽  
Vol 53 ◽  
pp. 406-407
Author(s):  
G. E. Spinnler ◽  
J. Liu
Keyword(s):  
Electron Microscopy ◽  
Noble Metal ◽  
Analytical Techniques ◽  
Sample Surface ◽  
High Resolution Electron Microscopy ◽  
Metal Particles ◽  
State University ◽  
Microscopy Imaging ◽  
Transmission Imaging ◽  
Resolution Electron

The location of metal particles contained in a zeolite-alumina binder support matrix has been difficult to solve using analytical techniques including electron microscopy. Imaging of metal particles, particularly noble metal particles on relatively light matrices such as zeolites or aluminas, has been easily accomplished using high angle annular darkfield imaging (HAADF). Since transmission imaging provides a projection through the sample, location of the particles in the sample or on the surface is not obvious. Surfacesensitive signals such as secondary electrons (SE) and Auger electrons (AE) are necessary to detect particles on the sample surface. HAADF, SE, and AE imaging have been applied to locate noble metal particles in a zeolite support with an alpha alumina binder.The samples were analyzed in a UHV HB501S STEM (MIDAS, Microscope for Imaging and Diffraction Analysis of Surfaces) at the Center for High Resolution Electron Microscopy at Arizona State University. The samples were prepared by crushing and dry deposition on a holey carbon grid.

Effect of oxygen on the stability of 1-D Lps in Cu3Pd

1990 ◽  
Vol 48 (4) ◽  
pp. 166-167
Author(s):  
P. Huang ◽  
E. S. K. Menon ◽  
G. Ceder ◽  
D. de Fontaine
Keyword(s):  
Single Phase ◽  
Theoretical Calculations ◽  
High Resolution Electron Microscopy ◽  
Pair Interaction ◽  
Deep Minimum ◽  
Two Phase ◽  
Resolution Electron ◽  
Diffraction Patterns ◽  
The Stability ◽  
Effect Of Oxygen

The variety of ordered phases exhibited by Cu-Pd alloys has led many investigators to study it both experimentally and theoretically. Recently, we have determined the Cu-rich portion of the Cu-Pd phase diagram (Fig. 1) and indicated that the region denoted as 1-d LPS actually represents a large number of single phase fields of long period superstructures (LPS) separated by narrow two phase regions in agreement with theoretical calculations. Each single phase field would correspond to an LPS with a characteristic modulation period, which can be measured from the splitting of the 001 reflection in diffraction patterns. High resolution electron microscopy (HREM) studies on Cu-Pd alloys have revealed that the antiphase boundaries (APB) associated with the LPS formed at low temperatures exhibit a sharp character, while those in LPS equilibrated at high temperatures are diffuse. In a recent theoretical study on LPS, Ceder et al. pointed out that the pair interaction potential in reciprocal space, V(k), associated with Cu-Pd alloys shows a rather deep minimum which arises as a result of flat sections on the Fermi surface. Ordering concentration waves located away from the minimum of V(k) would quickly disappear at higher temperatures because of their higher contribution to the configuration energy, thus leading to the formation of a smooth modulation profile. Consequently, in selected area diffraction patterns (SAD), only first order satellites are expected. On the other hand, at lower temperatures, where the contribution from the ordering concentration waves away from the minimum in V(k) is also significant, higher order satellites should be observable in SAD patterns.

Structural and Phase Transformations in Thin Film Ti-Aluminides and Ti/Al Multilayers

1996 ◽  
Vol 434 ◽  
Author(s):  
R. Banerjee ◽  
S. Swaminathan ◽  
R. Wheeler ◽  
H. L. Fraser
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Layer Thickness ◽  
High Resolution Electron Microscopy ◽  
Silicon Substrates ◽  
Two Phase ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Sputter Deposited

AbstractMultilayered Ti/Al thin films (with nominally equal layer thickness of Ti and Al) have been sputter deposited on oxidized silicon substrates at room temperature. Transmission electron microscopy (TEM) and high resolution electron microscopy have been used to characterize the structure of these multilayers as a function of the layer thickness. Ti changed from an hcp to an fcc and back to an hcp structure on reduction of the layer thickness. Al too changed from an fcc to an hcp structure at a layer thickness of 2.5 nm. The observed structural transitions have been explained on the basis of the Redfield-Zangwill model. Subsequently Ti-aluminide thin films were deposited using a γ-TiAl target. These films were found to be amorphous in the as-deposited condition with crystallites of α-Ti(Al) embedded in the amorphous matrix. On annealing under a protective Ar atmosphere at a temperature of 550 °C, the Ti-aluminide film crystallized into a nanocrystalline two phase microstructure consisting of γ-TiAl and α2-Ti3Al. The crystallization of the aluminide film has been investigated in detail by in-situ annealing experiments on a hot stage in the TEM. The results of this investigation have been discussed in this paper.

Sign in / Sign up

Export Citation Format

Share Document