Gold Nanoparticles at the Liquid−Liquid Interface: X-ray Study and Monte Carlo Simulation

Langmuir ◽  
2009 ◽  
Vol 25 (2) ◽  
pp. 952-958 ◽  
Author(s):  
Stephan Kubowicz ◽  
Markus A. Hartmann ◽  
Jean Daillant ◽  
Milan K. Sanyal ◽  
Ved V. Agrawal ◽  
...  
Keyword(s):  
Monte Carlo Simulation ◽  
Gold Nanoparticles ◽  
Monte Carlo ◽  
Liquid Interface ◽  
X Ray

Structure of a liquid/liquid interface during solvent extraction combining X-ray and neutron reflectivity measurements

2015 ◽  
Vol 17 (23) ◽  
pp. 15093-15097 ◽  
Author(s):  
E. Scoppola ◽  
E. Watkins ◽  
G. Li Destri ◽  
L. Porcar ◽  
R. A. Campbell ◽  
...  
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Solvent Extraction ◽  
Structural Information ◽  
Liquid Interface ◽  
Neutron Reflectivity ◽  
Distribution Profile ◽  
X Ray ◽  
Molecular Ordering

Combining neutron and X-ray reflectivity structural information from a liquid/liquid interface containing extractant molecules and ions is obtained. A Monte-Carlo simulation permits us to build a molar distribution profile across the interface, even if no molecular ordering exists.

scholarly journals Evaluation of dose enhancement with gold nanoparticles in kilovoltage radiotherapy using the new EGS geometry library in Monte Carlo simulation

2021 ◽  
Vol 8 (4) ◽  
pp. 337-345
Author(s):  
Zaynah Sheeraz ◽  
◽  
James C.L. Chow ◽  
◽  
Keyword(s):  
Monte Carlo Simulation ◽  
Gold Nanoparticles ◽  
Monte Carlo ◽  
Gold Nanoparticle ◽  
Particle Method ◽  
Tumour Volume ◽  
Water Mixture ◽  
Nanoparticle Concentration ◽  
Dose Enhancement ◽  
X Ray

<abstract><sec> <title>Purpose</title> <p>This study compared the dose enhancement predicted in kilovoltage gold nanoparticle-enhanced radiotherapy using the newly developed EGS lattice and the typical gold-water mixture method in Monte Carlo simulation. This new method considered the gold nanoparticle-added volume consisting of solid nanoparticles instead of a gold-water mixture. In addition, this particle method is more realistic in simulation.</p> </sec><sec> <title>Methods</title> <p>A heterogeneous phantom containing bone and water was irradiated by the 105 and 220 kVp x-ray beams. Gold nanoparticles were added to the tumour volume with concentration varying from 3–40 mg/mL in the phantom. The dose enhancement ratio (DER), defined as the ratio of dose at the tumour with and without adding gold nanoparticles, was calculated by the gold-water mixture and particle method using Monte Carlo simulation for comparison.</p> </sec><sec> <title>Results</title> <p>It is found that the DER was 1.44–4.71 (105 kVp) and 1.27–2.43 (220 kVp) for the gold nanoparticle concentration range of 3–40 mg/mL, when they were calculated by the gold-water mixture method. The DER was slightly larger and equal to 1.47–4.84 (105 kVp) and 1.29–2.5 (220 kVp) for the same concentration range, when the particle method was used. Moreover, the DER predicted by both methods increased with an increase of nanoparticle concentration, and a decrease of x-ray beam energy.</p> </sec><sec> <title>Conclusion</title> <p>The deviation of DER determined by the particle and gold-water mixture method was insignificant when considering the uncertainty in the calculation of DER (2%) in the nanoparticle concentration range of 3–40 mg/mL. It is therefore concluded that the gold-water mixture method could predict the dose enhancement as accurate as the newly developed particle method.</p> </sec></abstract>

Determination of Stoichiometry of GaAs Component in (Gaas)Ge Epitaxially Grown Thin Films by Electron Microprobe X-Ray Analysis

1990 ◽  
Vol 48 (2) ◽  
pp. 264-265
Author(s):  
D. R. Liu ◽  
S. S. Shinozaki ◽  
R. J. Baird
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Compound Semiconductors ◽  
Energy Dispersive Analysis ◽  
X Ray ◽  
Metastable Alloys ◽  
Lower Voltage

The epitaxially grown (GaAs)Ge thin film has been arousing much interest because it is one of metastable alloys of III-V compound semiconductors with germanium and a possible candidate in optoelectronic applications. It is important to be able to accurately determine the composition of the film, particularly whether or not the GaAs component is in stoichiometry, but x-ray energy dispersive analysis (EDS) cannot meet this need. The thickness of the film is usually about 0.5-1.5 μm. If Kα peaks are used for quantification, the accelerating voltage must be more than 10 kV in order for these peaks to be excited. Under this voltage, the generation depth of x-ray photons approaches 1 μm, as evidenced by a Monte Carlo simulation and actual x-ray intensity measurement as discussed below. If a lower voltage is used to reduce the generation depth, their L peaks have to be used. But these L peaks actually are merged as one big hump simply because the atomic numbers of these three elements are relatively small and close together, and the EDS energy resolution is limited.

scholarly journals Monte Carlo Modeling and Design of Photon Energy Attenuation Layers for >10× Quantum Yield Enhancement in Si-Based Hard X-ray Detectors

Instruments ◽  
2021 ◽  
Vol 5 (2) ◽  
pp. 17
Author(s):  
Eldred Lee ◽  
Kaitlin M. Anagnost ◽  
Zhehui Wang ◽  
Michael R. James ◽  
Eric R. Fossum ◽  
...  
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Quantum Yield ◽  
Photon Energy ◽  
High Efficiency ◽  
High Energy ◽  
Yield Enhancement ◽  
X Ray ◽  
Simulation Results ◽  
Conversion Efficiencies

High-energy (>20 keV) X-ray photon detection at high quantum yield, high spatial resolution, and short response time has long been an important area of study in physics. Scintillation is a prevalent method but limited in various ways. Directly detecting high-energy X-ray photons has been a challenge to this day, mainly due to low photon-to-photoelectron conversion efficiencies. Commercially available state-of-the-art Si direct detection products such as the Si charge-coupled device (CCD) are inefficient for >10 keV photons. Here, we present Monte Carlo simulation results and analyses to introduce a highly effective yet simple high-energy X-ray detection concept with significantly enhanced photon-to-electron conversion efficiencies composed of two layers: a top high-Z photon energy attenuation layer (PAL) and a bottom Si detector. We use the principle of photon energy down conversion, where high-energy X-ray photon energies are attenuated down to ≤10 keV via inelastic scattering suitable for efficient photoelectric absorption by Si. Our Monte Carlo simulation results demonstrate that a 10–30× increase in quantum yield can be achieved using PbTe PAL on Si, potentially advancing high-resolution, high-efficiency X-ray detection using PAL-enhanced Si CMOS image sensors.

Formation of GaN Self-Organized Nanotips by Nanomasking Effect

2001 ◽  
Vol 707 ◽  
Author(s):  
Harumasa Yoshida ◽  
Tatsuhiro Urushido ◽  
Hideto Miyake ◽  
Kazumasa Hiramtsu
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Aspect Ratio ◽  
Formation Mechanism ◽  
High Aspect Ratio ◽  
Photoelectron Spectroscopy ◽  
Nanometer Scale ◽  
Xps Analysis ◽  
X Ray ◽  
Self Organized

ABSTRACTWe have successfully fabricated self-organized GaN nanotips by reactive ion etching using chlorine plasma, and have revealed the formation mechanism. Nanotips with a high density and a high aspect ratio have been formed after the etching. We deduce from X-ray photoelectron spectroscopy (XPS) analysis that the nanotip formation is attributed to nanometer-scale masks of SiO2 on GaN. The structures calculated by Monte Carlo simulation of our formation mechanism are very similar to the experimental nanotip structures.

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