Gallium Plasmonic Nanoantennas Unveiling Multiple Kinetics of Hydrogen Sensing, Storage, and Spillover.

Hydrogen is the key element to accomplish a carbon-free based economy. Here, the first evidence of plasmonic gallium (Ga) nanoantennas is provided as nanoreactors supported on sapphire (α-Al O ) acting as direct plasmon-enhanced photocatalyst for hydrogen sensing, storage, and spillover. The role of plasmon-catalyzed electron transfer between hydrogen and plasmonic Ga nanoparticle in the activation of those processes is highlighted, as opposed to conventional refractive index-change-based sensing.

Sustainable and Tunable Mg/MgO Plasmon-Catalytic Platform for the Grand Challenge of SF Environmental Remediation.

Sulfur hexafluoride (SF) is one of the most harmful greenhouse gases producing environmental risks. Therefore, developing ways of degrading SF without forming hazardous products is increasingly important. Herein, we demonstrate for the first time the plasmon-catalytic heterogeneous degradation of SF into nonhazardous MgF and MgSO products by nontoxic and sustainable plasmonic magnesium/magnesium oxide (Mg/MgO) nanoparticles, which are also effective as a plasmon-enhanced SF chemometric sensor.

Optically addressing interaction of Mg/MgO plasmonic systems with hydrogen.

Magnesium-based films and nanostructures are being studied in order to improve hydrogen reversibility, storage capacity, and kinetics, because of their potential in the hydrogen economy. Some challenges with magnesium (Mg) samples are their unavoidable oxidation by air exposure and lack of direct in situ real time measurements of hydrogen interaction with Mg and MgO surfaces and Mg plasmonic nanoparticles. Given these challenges, the present article investigates direct interaction of Mg with hydrogen, as well as implications of its inevitable oxidation by real-time spectroscopic ellipsometry for exploiting the optical properties of Mg, MgH and MgO.

Unidirectional lateral nanowire formation during the epitaxial growth of GaAsBi on vicinal substrates.

We report on enhanced control of the growth of lateral GaAs nanowires (NWs) embedded in epitaxial (100) GaAsBi thin films enabled by the use of vicinal substrates and the growth-condition dependent role of Bi as a surfactant. Enhanced step-flow growth is achieved through the use of vicinal substrates and yields unidirectional nanowire growth. The addition of Bi during GaAsBi growth enhances Ga adatom diffusion anisotropy and modifies incorporation rates at steps in comparison to GaAs growth yielding lower density but longer NWs.

Thermally stable coexistence of liquid and solid phases in gallium nanoparticles.

Gallium (Ga), a group III metal, is of fundamental interest due to its polymorphism and unusual phase transition behaviours. New solid phases have been observed when Ga is confined at the nanoscale. Herein, we demonstrate the stable coexistence, from 180 K to 800 K, of the unexpected solid γ-phase core and a liquid shell in substrate-supported Ga nanoparticles.

Gallium plasmonics: deep subwavelength spectroscopic imaging of single and interacting gallium nanoparticles.

Gallium has recently been demonstrated as a phase-change plasmonic material offering UV tunability, facile synthesis, and a remarkable stability due to its thin, self-terminating native oxide. However, the dense irregular nanoparticle (NP) ensembles fabricated by molecular-beam epitaxy make optical measurements of individual particles challenging. Here we employ hyperspectral cathodoluminescence (CL) microscopy to characterize the response of single Ga NPs of various sizes within an irregular ensemble by spatially and spectrally resolving both in-plane and out-of-plane plasmonic modes.

Demonstrating the capability of the high-performance plasmonic gallium-graphene couple.

Metal nanoparticle (NP)-graphene multifunctional platforms are of great interest for exploring strong light-graphene interactions enhanced by plasmons and for improving performance of numerous applications, such as sensing and catalysis. These platforms can also be used to carry out fundamental studies on charge transfer, and the findings can lead to new strategies for doping graphene. There have been a large number of studies on noble metal Au-graphene and Ag-graphene platforms that have shown their potential for a number of applications.

Ultraviolet nanoplasmonics: a demonstration of surface-enhanced Raman spectroscopy, fluorescence, and photodegradation using gallium nanoparticles.

Self-assembled arrays of hemispherical gallium nanoparticles deposited by molecular beam epitaxy on a sapphire support are explored as a new type of substrate for ultraviolet plasmonics. Spin-casting a 5 nm film of crystal violet upon these nanoparticles permitted the demonstration of surface-enhanced Raman spectra, fluorescence, and degradation following excitation by a HeCd laser operating at 325 nm. Measured local Raman enhancement factors exceeding 10(7) demonstrate the potential of gallium nanoparticle arrays for plasmonically enhanced ultraviolet detection and remediation.

Personalized diagnostics and biosensors: a review of the biology and technology needed for personalized medicine.

Exploiting the burgeoning fields of genomics, proteomics and metabolomics improves understanding of human physiology and, critically, the mutations that signal disease susceptibility. Through these emerging fields, rational design approaches to diagnosis, drug development and ultimately personalized medicine are possible. Personalized medicine and point-of-care testing techniques must fulfill a host of constraints for real-world applicability.

Mixed semiconductor alloys for optical devices.

There is an increasing technological need for a wider array of semiconducting materials that will allow greater control over the physical and electronic structure within multilayer heterostructures. This need has led to an expansion in the range of semiconducting alloys explored and used in new applications. These alloy semiconductors are often complicated by a limited range of miscibility.

Direct optical imaging of graphene in vitro by nonlinear femtosecond laser spectral reshaping.

Nonlinear optical microscopy, based on femtosecond laser spectral reshaping, characterized and imaged graphene samples made from different methods, both on slides and in a biological environment. This technique clearly discriminates between graphene flakes with different numbers of layers and reveals the distinct nonlinear optical properties of reduced graphene oxide as compared to mechanically exfoliated or chemical vapor deposition grown graphene. The nonlinearity makes it applicable to scattering samples (such as tissue) as opposed to previous methods, such as transmission.

Cysteamine-based functionalization of InAs surfaces: revealing the critical role of oxide interactions in biasing attachment.

Attaching functional molecules such as thiols and proteins to semiconductor surfaces is increasingly exploited in functional devices such as sensors. Despite extensive research to understand this interface and demonstrate a robust protocol for attachment, the bonding chemistry of thiolates to III-V surfaces has been under great debate in the literature. This study provides a comprehensive chemical model for the attachment of thiols to InAs, an increasingly device-relevant III-V semiconductor, using cysteamine as a model molecule.

Demonstration of surface-enhanced Raman scattering by tunable, plasmonic gallium nanoparticles.

Size-controlled gallium nanoparticles deposited on sapphire were explored as alternative substrates to enhance Raman spectral signatures. Gallium's resilience following oxidation is inherently advantageous in comparison with silver for practical ex vacuo nonsolution applications. Ga nanoparticles were grown using a simple molecular beam epitaxy-based fabrication protocol, and monitoring their corresponding surface plasmon resonance energy through in situ spectroscopic ellipsometry allowed the nanoparticles to be easily controlled for size.

Plasmonic gallium nanoparticles on polar semiconductors: interplay between nanoparticle wetting, localized surface plasmon dynamics, and interface charge.

Ga nanoparticles supported on large band gap semiconductors like SiC, GaN, and ZnO are interesting for plasmon-enhanced UV-emitting solid-state devices. We investigate the influence of the polarity of the SiC, GaN, and ZnO wurtzite semiconductors on the wetting of Ga nanoparticles and on the resulting surface plasmon resonance (SPR) by exploiting real time plasmonic ellipsometry. The interface potential between polar semiconductors (SiC, GaN, and ZnO) and plasmonic nanoparticles (gallium) is shown to influence nanoparticle formation dynamics, geometry, and consequently the SPR wavelength.