Quantum dots (QDs) generally refer to nanoscale particles of conventional semiconductors that are subject the quantum-confinement effect, though other nanomaterials similar optical and redox properties also named as QDs even in absence strictly defined quantum confinement. Among such have attracted tremendous recent interest carbon dots, which small nanoparticles with some form surface passivation, graphene various configurations. In this article, we highlight these carbon-based by focusing...

Helium nanodroplets have emerged as a new and exciting medium for studying the structure dynamics of both this quantum solvent impurities that can be doped into (onto) grown inside (on surface) droplets. Spectroscopic studies these molecular provide detailed information on helium its interaction with solute. This is particularly important given completely transparent to photons below 20 eV, making direct spectroscopic study liquid problematic. Since an extremely weak solvent, corresponding...

Fluorescence intensities of carbon dots are substantially enhanced in the confined environment polymeric films.

Carbon "quantum" dots (or carbon dots) have emerged as a new class of optical nanomaterials. Beyond the widely reported bright fluorescence emissions in dots, their excellent photoinduced redox properties that resemble those found conventional semiconductor nanostructures are equally valuable, with photon-electron conversion applications from photovoltaics to CO2 photocatalytic reduction. In this work we used gold-doped controlled synthesis water-soluble catalysts for closer examination...

Using sonochemistry to provide the thermal energy and mixing, we demonstrate ability synthesize air-stable aluminum nanoparticles of two different size distributions from titanium-catalyzed decomposition alane. Characterization data indicate presence spherical face-centered-cubic with average sizes either 5 or 30 nm that are capped an organic shell. The correlates concentration passivation agent oleic acid, where a higher results in smaller particles. Thermal analysis demonstrates at...

Organically capped metal nanoparticles are an attractive alternative to more conventional oxide-passivated materials, due the lower reaction temperatures and possibility of tuning organic coating. Sonochemical methods have been used produce small (∼5 nm average size) air-stable aluminum with oleic acid. In order understand nature metal−organic bonding in nanoparticles, we FTIR, XPS, TOFMS−TPD techniques study passivation layer its desorption at elevated temperatures. present case find that...

Reported here is a study of the effects liquid helium cooling on fragmentation ions formed by electron impact mass ionization. The molecules interest are picked up nanodroplets as they pass through low pressure oven. Electron ionization atom in droplet followed resonant charge transfer to neighboring atoms. When transferred target molecule, difference potentials between and molecule results formation vibrationally hot ion. In isolation, parent ion would undergo subsequent fragmentation. On...

Electron impact ionization of a helium atom in nanodroplet is followed by rapid charge migration, which can ultimately result the localization on an atomic or molecular solute. This process studied here for cases hydrogen cyanide, acetylene, and cyanoacetylene helium, using new experimental method we call optically selected mass spectrometry (OSMS). The combines infrared laser spectroscopy with to separate contributions overall droplet beam spectrum from various species present under given...

Time-resolved emission spectroscopy and high-speed photography were used to study the chemical dynamics thermal history of aluminized hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) charges following detonation. The RDX contained 20 wt. % either 30-70 nm or 16-26 µm Al particles. Non-aluminized also studied for comparison. Spectra collected from exhibited AlO emissions during first ∼60 µs, followed by a broadband that evolved over two time scales: one in early time, 0-200 µsec, another on late...

The energy release dynamics of explosives are ongoing interest, but the short timescales involved often limit measurements that can be made during these processes. We have used atomic emission spectroscopy to measure temperature fireballs resulting from detonation charges Hexahydro-1,3,5-trinitro-1,3,5-triazine doped with barium nitrate. time-averaged spectra indicate an apparent ∼3000 K, in good agreement theoretical predictions. technique demonstrated herein should applicable time-resolved...

Aluminum nanoparticles have been a subject of active investigation in recent years because their potential to enhance the energy content energetic materials. The associated kinetics chemical reaction and release are, many cases, governed by properties passivation layer protecting particle rather than those underlying metal core. Al particles is typically an oxide shell several nanometers thick, but other possibilities are now available. We previously developed synthesis routes produce...

In recent years, emission spectroscopy has been applied to the study of post-detonation combustion in explosives, often yielding valuable information on temperatures and chemical dynamics. The fireballs that form as under-oxidized detonation products burn surrounding air are optically dense corresponding spectra sample only material at or near surface fireball. present study, we exploit large optical density order probe dynamics occurring interior Emission collected following 20 g aluminized...

Aluminum nanoparticles and explosive formulations that incorporate them have been a subject of ongoing interest due to the potential aluminum particles dramatically increase energy content relative conventional organic explosives. We used time-resolved atomic molecular emission spectroscopy monitor combustion within overall chemical dynamics post-detonation fireballs. studied release hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) charges incorporating three types nanoparticles: commercial...

This essay continues the challenge to image of law as neutral adjudication by arguing that, while authoritative judicial discourse in modern liberal state has presented itself realistic that argues singular conclusions, it is better see a profoundly rhetorical enterprise writes legal decisions romances which Law heroic central character. Focusing on first flag burning case Texas v. Johnson, examines decision argument and romance. It concludes suggesting (and general) would benefit from sense...

A technique that combines infrared laser spectroscopy and helium nanodroplet mass spectrometry, which we refer to as optically selected is used study the efficiency of ion cooling in helium. Electron-impact ionization form He+ ions within droplets, go on transfer their charge HCN dopant molecules. Depending upon droplet size, newly formed either fragments or cooled by before fragmentation can occur. Comparisons with gas-phase data suggest provided highly nonthermal. An “explosive” model...

The ionization and charge transfer processes, which occur when a doped helium droplet undergoes electron impact, are studied for droplets with van der Waals complexes various structures electrostatic moments. mass spectra of the two isomers hydrogen cyanide complexed either cyanoacetylene or acetylene in were obtained using optically selected spectrometry, show that structure complex has large effect on fragmentation pattern. resulting pattern is consistent an process steering strongly...

Helium droplet beam methods are a versatile technique that can be used to assemble wide variety of atomic and molecular clusters. In recent years, have been developed utilize helium droplets as nano-calorimeters measure the binding energies weakly bound complexes assembled within droplet. current investigation we extend calorimetry approach study very strongly system: carbon clusters which by several eV per atom. We laser heating bulk samples dope with evaporated species. Depending on...

In situ mass spectrometry is demonstrated as a technique to study the pyrolysis of neat fluids at supercritical conditions. These included pure hexane, benzene, and binary mixtures two, which were sampled in supersonic expansion cool trap reactants, intermediates, products molecular beam. To identify reacting species, beam was subjected electron impact ionization prior analysis quadrupole filter. addition previously reported gas-phase for hexane we observe enhanced production biphenyl...

Incorporating high energy nanoparticulate additives is considered as a means to enhance the performance of hypergolic ionic liquid (IL) propellants. In this manuscript, we demonstrate content borane–aluminum nanoparticles produced by ball milling and examine ignition combustion behavior ILs loaded with up 30 weight percent (wt %) particles, measured two different methods. The goal better understand effects particle loading on mechanism. Bomb calorimetry differential scanning...

The catalytic reduction of CO2 to produce hydrocarbon fuels is a topic that has gained significant attention. Development efficient catalysts key enabler such approaches, and metal-based have shown promise towards this goal. development fundamental understanding the interactions between molecules metal atoms expected offer insight into chemistry occurs at active site catalysts. In current study, we utilize helium droplet methods assemble complexes composed molecule Mg or Al atom....

Perhaps the fullest expression of contrast between law as a set rules or bureaucratic system and literature rhetoric language' is work James Boyd White. In series books articles, White has explored cultural critique by considering life to be kind discourse that engenders special ethical political community.2 While my main intent critique, I want begin celebrating position underlies what calls literary practice rhetorical character law: fundamental recognitions language shapes perception...

A strategy for forming and detecting cold ion-neutral clusters using superfluid helium nanodroplets is described. Sodium cations generated via thermionic emission are directed toward a beam of droplets that can also pick up neutral molecules form cluster with the captured Na+. The composition determined by mass spectrometric analysis following desolvation step. It shown polar H2O HCN picked sizes relative abundances in good agreement those predicted statistics used to describe formation...