Search results for "A2"

Covalently linked multimers of gold nanoclusters Au102(p-MBA)44and Au∼250(p-MBA)n

2016

We present the synthesis, separation, and characterization of covalently-bound multimers of para-mercaptobenzoic acid (p-MBA) protected gold nanoclusters. The multimers were synthesized by performing a ligand-exchange reaction of a pre-characterized Au102(p-MBA)44 nanocluster with biphenyl-4,4′-dithiol (BPDT). The reaction products were separated using gel electrophoresis yielding several distinct bands. The bands were analyzed by transmission electron microscopy (TEM) revealing monomer, dimer, and trimer fractions of the nanocluster. TEM analysis of dimers in combination with molecular dynamics simulations suggest that the nanoclusters are covalently bound via a disulfide bridge between BP…

About the dynamics of strongly coupled surface plasmon polaritons and Sulforhodamine 101

2014

We investigate the dynamics of strongly coupled surface plasmon polaritons (SPP) and molecular excitations (ME) of Sulforhodamine 101 dye. The SPPs are excited by prism coupling technique on a thin silver film with dye molecules embedded in a polymer layer on top of it. Rabi splittings with energies of 135 and 97 meV are observed in the recorded dispersion relations. Both coupled oscillator model and transfer matrix method are used to fit the experimental results. In addition to the common reflectance measurements, polarization resolved detection of scattered signal from the molecular side is also utilized. Simultaneous detection of the scattered polaritons and molecular fluorescence reveal…

Au102(p-MBA)44 nanocluster, a superatom suitable for bio-applications

2016

Inorganic nanoparticles, including metals, semiconductors and metal oxides, comprise a common set of structures exhibiting an inorganic core ‘passivated’ by an organic shell. Ligated inorganic nanoparticles currently provoke widespread fundamental interest in their structural, optical and magnetic properties, which differ fundamentally from bulk counterparts. These nanomaterials are already finding applications in biology, medicine, solar energy, and display panels. 1-6 Conjugating inorganic nanoparticles with organic (biological) material for applications in nanobiology and nanomedicine creates significant challenges for controlling the effects on the environment, particularly regarding to…

Measurements of the transport gap in semiconducting multiwalled carbon nanotubes with varying diameter and length

2015

Low temperature transport in multiwalled carbon nanotubes (MWNTs) has been studied at different diameters and lengths, within 2–10 nm, and 0.3–3.5μm, respectively. In a majority of the samples, semiconductivity showed up as a transport gap in the gate voltage controlled conduction, but metallic MWNTs are found in all diameters. The transport gap is seen to be quantitatively determined by a diameter dependent band gap, and length dependent localization of charge carriers. The band gap of semiconducting MWNTs is estimated to be smaller than that extrapolated from the conventional expression applicable to semiconducting single wall carbon nanotubes. The results constitute a systematical study …

Novel Methodologies to Model Charge Transport in Metal-Air Batteries

2018

A subthreshold, low-power, RHBD reference circuit, for earth observation and communication satellites

2015

A low-power, wide temperature range, radiation tolerant CMOS voltage reference is presented. The proposed reference circuit exhibits a voltage deviation of 0.8mV for 3-MeV protons total ionization dose of 2Mrad and a voltage deviation of 3.8mV for 10-keV X-rays total ionization dose of 4Mrad while being biased at the nominal supply voltage of 0.75V during X-ray irradiation. In addition, the circuit consumes only 4μW and exhibits a measured Temperature Drift of 15ppm/°C for a temperature range of 190°C (−60°C to 130°C) at the supply voltage of 0.75V. It utilizes only CMOS transistors, operating in the subthreshold regime, and poly-silicon resistors without using any diodes or external compon…

Vacuum Rabi splitting for surface plasmon polaritons and Rhodamine 6G molecules

2011

We report on strong coupling between surface-plasmon polaritons and Rhodamine 6G molecules at room temperature. As a reference to compare with, we first determine the dispersion curve of (uncoupled) surface plasmon polaritons on a 50 nm thick film of silver. Consequently, we determine the dispersion curve of surface plasmon polaritons strongly coupled to Rhodamine 6G molecules, which exhibits vacuum Rabi splitting. Depending on the Rhodamine 6G concentration, we find splitting energies between 0.05 eV and 0.13 eV.

Plasma etch characteristics of aluminum nitride mask layers grown by low-temperature plasma enhanced atomic layer deposition in SF6 based plasmas

2012

The plasma etch characteristics of aluminum nitride (AlN) deposited by low-temperature, 200 °C, plasma enhanced atomic layer deposition (PEALD) was investigated for reactive ion etch (RIE) and inductively coupled plasma-reactive ion etch (ICP-RIE) systems using various mixtures of SF6 and O2 under different etch conditions. During RIE, the film exhibits good mask properties with etch rates below 10r nm/min. For ICP-RIE processes, the film exhibits exceptionally low etch rates in the subnanometer region with lower platen power. The AlN film’s removal occurred through physical mechanisms; consequently, rf power and chamber pressure were the most significant parameters in PEALD AlN film remova…

Template-Free Supracolloidal Self-Assembly of Atomically Precise Gold Nanoclusters : From 2D Colloidal Crystals to Spherical Capsids

2016

We report supracolloidal self-assembly of atomically precise and strictly monodisperse gold nanoclusters involving p-mercaptobenzoic acid ligands (Au102-pMBA44) under aqueous conditions into hexagonally packed monolayer-thick two-dimensional facetted colloidal crystals (thickness 2.7 nm) and their bending to closed shells leading to spherical capsids (d ca. 200 nm), as controlled by solvent conditions. The 2D colloidal assembly is driven in template-free manner by the spontaneous patchiness of the pMBA ligands around the Au102-pMBA44 nanoclusters preferably towards equatorial plane, thus promoting inter-nanocluster hydrogen bonds and high packing to planar sheets. More generally, the findin…

Stabilizing organic photocathodes by low-temperature atomic layer deposition of TiO2

2017

Organic semiconductor light absorbers are receiving attention for their potential application in photoelectrochemical (PEC) cells for renewable fuels generation. Key to their advancement is precise control of the interfaces between charge-selective contacts, absorber layers, and electrocatalysts, while maintaining compatibility with an aqueous electrolyte environment. Here we demonstrate a new process for low-temperature atomic layer deposition (ALD) of TiO2 onto a P3HT:PCBM polymer blend surface for stable high-performance organic PEC photocathodes. This ALD TiO2 layer provides three key functions: (1) formation of an electron-selective contact to the polymer to enable photovoltage and pho…