X-Ray Absorption of Gold Nanoparticles with Thin Silica Shell

2006 ◽  
Vol 6 (11) ◽  
pp. 3503-3506 ◽  
Author(s):  
Yeon-Su Park ◽  
Luis M. Liz-Marzán ◽  
Atsuo Kasuya ◽  
Yoshio Kobayashi ◽  
Daisuke Nagao ◽  
...  
Keyword(s):  
Contrast Agent ◽  
Au Nanoparticles ◽  
Aqueous Media ◽  
Peak Position ◽  
Silica Shell ◽  
Absorption Properties ◽  
Experimental Conditions ◽  
X Ray ◽  
Transmission Electron ◽  
X Ray Absorption

Silica-coated gold (Au) nanoparticles were prepared and their morphological and X-ray absorption properties were investigated. These core–shell type nanoparticles are very stable in aqueous media and may be suitable for an X-ray contrast agent in biological systems. Transmission electron micrographs confirmed well-separated and relatively homogeneous morphology of the nanoparticles in highly concentrated colloids. Peak position for Au plasmon resonance was red-shifted with increasing shell thickness. X-ray absorption by the colloids of silica-coated Au nanoparticles was stronger than that by those of silica-coated AgI nanoparticles, a recently investigated X-ray contrast agent, at similar experimental conditions.

X-ray microanalysis of thin specimens in the transmission electron microscope at voltages up to 1000 Kv.

1978 ◽  
Vol 36 (1) ◽  
pp. 540-541
Author(s):  
G. Cliff ◽  
M.J. Nasir ◽  
G.W. Lorimer ◽  
N. Ridley
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Weight Fraction ◽  
Present Series ◽  
Constant Independent ◽  
X Ray ◽  
Transmission Electron ◽  
Series Of Experiments ◽  
Image Position ◽  
X Ray Absorption

In a specimen which is transmission thin to 100 kV electrons - a sample in which X-ray absorption is so insignificant that it can be neglected and where fluorescence effects can generally be ignored (1,2) - a ratio of characteristic X-ray intensities, I1/I2 can be converted into a weight fraction ratio, C1/C2, using the equationwhere k12 is, at a given voltage, a constant independent of composition or thickness, k12 values can be determined experimentally from thin standards (3) or calculated (4,6). Both experimental and calculated k12 values have been obtained for K(11<Z>19),kα(Z>19) and some Lα radiation (3,6) at 100 kV. The object of the present series of experiments was to experimentally determine k12 values at voltages between 200 and 1000 kV and to compare these with calculated values.The experiments were carried out on an AEI-EM7 HVEM fitted with an energy dispersive X-ray detector.

scholarly journals Structural Evolution in Wet Mechanically Alloyed Co-Fe-(Ta,W)-B Alloys

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 800
Author(s):  
Vladimír Girman ◽  
Maksym Lisnichuk ◽  
Daria Yudina ◽  
Miloš Matvija ◽  
Pavol Sovák ◽  
...  
Keyword(s):  
Structural Changes ◽  
Magnetic Measurements ◽  
Structural Evolution ◽  
High Energy ◽  
Control Agent ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
X Ray ◽  
Transmission Electron ◽  
X Ray Absorption

In the present study, the effect of wet mechanical alloying (MA) on the glass-forming ability (GFA) of Co43Fe20X5.5B31.5 (X = Ta, W) alloys was studied. The structural evolution during MA was investigated using high-energy X-ray diffraction, X-ray absorption spectroscopy, high-resolution transmission electron microscopy and magnetic measurements. Pair distribution function and extended X-ray absorption fine structure spectroscopy were used to characterize local atomic structure at various stages of MA. Besides structural changes, the magnetic properties of both compositions were investigated employing a vibrating sample magnetometer and thermomagnetic measurements. It was shown that using hexane as a process control agent during wet MA resulted in the formation of fully amorphous Co-Fe-Ta-B powder material at a shorter milling time (100 h) as compared to dry MA. It has also been shown that substituting Ta with W effectively suppresses GFA. After 100 h of MA of Co-Fe-W-B mixture, a nanocomposite material consisting of amorphous and nanocrystalline bcc-W phase was synthesized.

Ferromagnetism and Luminescence of Diluted Magnetic Semiconductors GaGdN and AlGdN

2008 ◽  
Vol 1111 ◽  
Author(s):  
Shuichi Emura ◽  
Masahiro Takahashi ◽  
Hiroyuki Tambo ◽  
Akira Suzuki ◽  
Tetsuya Nakamura ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Diluted Magnetic Semiconductors ◽  
Magnetic Semiconductors ◽  
Magnetic Circular Dichroism ◽  
Peak Position ◽  
Magnetic Characteristics ◽  
Sharp Line ◽  
X Ray ◽  
Diluted Magnetic ◽  
X Ray Absorption

AbstractThe magnetic characteristics of the dilute magnetic system GaGdN are investigated by mainly soft-X-ray magnetic circular dichroism (MCD) in energy range of 1160 – 1240 eV. The strong MCD signals up to 30 % at 15K are observed. The temperature dependence of its intensity is not on simple Curie-Weiss curve and depicts three-step curve. A step around 40 – 100K suggests a new magnetic phase. The luminescence spectrum of GaGdN at low temperature is divided into three parts consisting of two broad bands around 432 nm and 503 nm and a sharp peak at 652 nm. This sharp line is assigned to the intra-transition of f – f orbital owing to the weak temperature dependence of the intensity and peak position. AlGdN grown by molecular beam epitaxy produces luminescence at 318.5 nm. X-ray absorption fine structure is examined to survey the occupancy of the Gd ion in the grown specimens.

Size dependent behavior of Fe3O4crystals during electrochemical (de)lithiation: an in situ X-ray diffraction, ex situ X-ray absorption spectroscopy, transmission electron microscopy and theoretical investigation

2017 ◽  
Vol 19 (31) ◽  
pp. 20867-20880 ◽  
Author(s):  
David C. Bock ◽  
Christopher J. Pelliccione ◽  
Wei Zhang ◽  
Janis Timoshenko ◽  
K. W. Knehr ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
X Ray ◽  
Size Dependent ◽  
Transmission Electron ◽  
Dependent Behavior ◽  
X Ray Absorption

Crystal and atomic structural changes of Fe3O4upon electrochemical (de)lithiation were determined.

Structural aspects of the hisingerite-neotocite series

Clay Minerals ◽  
1983 ◽  
Vol 18 (1) ◽  
pp. 21-31 ◽  
Author(s):  
R. A. Eggleton ◽  
J. H. Pennington ◽  
R. S. Freeman ◽  
I. M. Threadgold
Keyword(s):  
Function Analysis ◽  
Pore Space ◽  
Hollow Spheres ◽  
X Ray ◽  
Broken Hill ◽  
Transmission Electron ◽  
X Ray Absorption ◽  
Interconnected Pore ◽  
Intermediate Member ◽  
Structural Aspects

AbstractTransmission electron microscopy, X-ray radial distribution function analysis, chemical analysis, X-ray absorption edge spectroscopy, and Mössbauer spectroscopy combine to confirm an amorphous or gel structure for minerals of the hisingerite-neotocite series: (Fe,Mn)0.8SiO3.1.2H2O. A framework of (Fe,Mn)O6 octahedra and [SiO4] tetrahedra form hollow spheres, 50–100 Å in diameter, cross-bonded into a physically isotropic solid with as much as 10% interconnected pore space. The outer 10–20 Å of the spheres has a rudimentary structure, possibly marking the onset of segregation into Si-rich and (Fe,Mn)-rich layers. The Broken Hill mineral ‘sturtite’ is an intermediate member of the hisingerite-neotocite series.

scholarly journals Volcano-Type Correlation between Particle Size and Catalytic Activity on Hydrodechlorination catalyzed by AuPd Nanoalloy

2020 ◽  
Author(s):  
Yuta Uetake ◽  
Sachi Mouri ◽  
Setsiri Haesuwannakij ◽  
Kazu Okumura ◽  
Hidehiro Sakurai
Keyword(s):  
Catalytic Activity ◽  
Metal Ion ◽  
Mixing Time ◽  
Metal Nanoparticle ◽  
Edge Structure ◽  
X Ray ◽  
Rate Determining Step ◽  
Transmission Electron ◽  
Random Alloy ◽  
X Ray Absorption

<div>Although changing the size of metal nanoparticle (NP) is a reasonable way to tune and/or enhance their catalytic activity, size-selective preparation of NP possessing random-alloy morphology has been challenging because of the differences in the ionization potential of each metal ion. This study demonstrates a time-controlled aggregation–stabilization method for a size-selective preparation of random alloy NPs composed of Au and Pd, which are stabilized by poly(<i>N</i>-vinyl-2-pyrrolidone) (PVP). By adjusting the mixing time in the presence of a small amount of PVP, the aggregation was induced to produce AuPd:PVP with sizes ranging between 1.2 and 8.2 nm at approximately 1 nm intervals. Transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and extended x-ray absorption fine structure (EXAFS) analyses clearly indicated the formation of various sizes of AuPd nanoalloys with almost the same morphology, and size-dependent catalytic activity was observed when hydrodechlorination of 4-choroanisole was performed using 2-propanol as a reducing agent. AuPd:PVP with a size of 3.1 nm exhibited the highest catalytic activity. A comparison of the absorption edges on x-ray absorption near edge structure (XANES) spectra suggested that the electronic state of the Au and Pd species correlated with their catalytic activity, presumably affecting the rate-determining step.</div><div> </div>

Aquatic Fern (AzollaSp.) Assisted Synthesis of Gold Nanoparticles

2016 ◽  
Vol 15 (01n02) ◽  
pp. 1650008 ◽  
Author(s):  
Anal K. Jha ◽  
K. Prasad
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gold Nanoparticles ◽  
Surface Plasmon Resonance ◽  
Au Nanoparticles ◽  
X Ray ◽  
Aquatic Fern ◽  
Transmission Electron ◽  
Anthraquinone Glycosides ◽  
Uv Visible

Aquatic pteridophyte (Azolla sp.) was taken to assess its potential to synthesize the metal (Au) nanoparticles. The synthesized particles were characterized using X-ray, UV-visible, scanning and transmission electron microscopy analyses. Nanoparticles almost spherical in shape having the sizes of 5–17[Formula: see text]nm are found. UV-visible study revealed the surface plasmon resonance at 538[Formula: see text]nm. Responsible phytochemicals for the transformation were principally phenolics, tannins, anthraquinone glycosides and sugars present abundantly in the plant thereby bestowing it adaptive prodigality. Also, the use of Azolla sp. for the synthesis of gold nanoparticles offers the benefit of eco-friendliness.

scholarly journals Observation and Characterization of Fragile Organometallic Molecules Encapsulated in Single-Wall Carbon Nanotubes

2014 ◽  
Vol 2014 ◽  
pp. 1-5
Author(s):  
Daisuke Ogawa ◽  
Ryo Kitaura ◽  
Takeshi Saito ◽  
Shinobu Aoyagi ◽  
Eiji Nishibori ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
High Yield ◽  
Single Wall Carbon Nanotubes ◽  
X Ray Diffraction ◽  
Single Wall Carbon ◽  
X Ray ◽  
Transmission Electron ◽  
Organometallic Molecules ◽  
X Ray Absorption

Thermally fragile tris(η5-cyclopentadienyl)erbium (ErCp3) molecules are encapsulated in single-wall carbon nanotubes (SWCNTs) with high yield. We realized the encapsulation of ErCp3with high filling ratio by using high quality SWCNTs at an optimized temperature under higher vacuum. Structure determination based on high-resolution transmission electron microscope observations together with the image simulations reveals the presence of almost free rotation of each ErCp3molecule in SWCNTs. The encapsulation is also confirmed by X-ray diffraction. Trivalent character of Er ions (i.e., Er3+) is confirmed by X-ray absorption spectrum.

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