Parallelized Acquisition of Orbitrap and Astral Analyzers Enables High-Throughput Quantitative Analysis.

The growing trend toward high-throughput proteomics demands rapid liquid chromatography-mass spectrometry (LC-MS) cycles that limit the available time to gather the large numbers of MS/MS fragmentation spectra required for identification. Orbitrap analyzers scale performance with acquisition time and necessarily sacrifice sensitivity and resolving power to deliver higher acquisition rates. We developed a new mass spectrometer that combines a mass-resolving quadrupole, the Orbitrap, and the novel Asymmetric Track Lossless (Astral) analyzer. The new hybrid instrument enables faster acquisition of high-resolution accurate mass (HRAM) MS/MS spectra compared with state-of-the-art mass spectrometers. Accordingly, new proteomics methods were developed that leverage the strengths of each HRAM analyzer, whereby the Orbitrap analyzer performs full scans with a high dynamic range and resolution, synchronized with the Astral analyzer's acquisition of fast and sensitive HRAM MS/MS scans. Substantial improvements are demonstrated over previous methods using current state-of-the-art mass spectrometers.

Role of Gas Molecule Complexity in Environmental Electron Microscopy and Photoelectron Yield Spectroscopy.

Environmental scanning electron microscopy (ESEM) and environmental photoelectron yield spectroscopy (EPYS) enable electron imaging and spectroscopy of surfaces and interfaces in low-vacuum gaseous environments. The techniques are both appealing and limited by the range of gases that can be used to amplify electrons emitted from a sample and used to form images/spectra. However, to date only H2O and NH3 gases have been identified as highly favorable electron amplification media. Here we demonstrate that ethanol vapor (CH3CH2OH) is superior to both of these and attribute its performance to its molecular complexity and valence orbital structure. Our findings improve the present understanding of what constitutes a favorable electron amplification gas and will help expand the applicability and usefulness of the ESEM and EPYS techniques.

Silicon oxide nanowire growth mechanisms revealed by real-time electron microscopy.

Growth of one-dimensional materials is possible through numerous mechanisms that affect the nanowire structure and morphology. Here, we explain why a wide range of morphologies is observed when silicon oxide nanowires are grown on silicon substrates using liquid gallium catalyst droplets. We show that a gallium oxide overlayer is needed for nanowire nucleation at typical growth temperatures, and that it can decompose during growth and, hence, dramatically alter the nanowire morphology. Gallium oxide decomposition is attributed to etching caused by hydrogen that can be supplied by thermal dissociation of H2O (a common impurity). We show that H2O dissociation is catalyzed by silicon substrates at temperatures as low as 320 °C, identify the material supply pathways and processes that rate-limit nanowire growth under dry and wet atmospheres, and present a detailed growth model that explains contradictory results reported in prior studies. We also show that under wet atmospheres the Ga droplets can be mobile and promote nanowire growth as they traverse the silicon substrate.

Synthesis of luminescent europium defects in diamond.

Lanthanides are vital components in lighting, imaging technologies and future quantum memory applications owing to their narrow optical transitions and long spin coherence times. Recently, diamond has become a pre-eminent platform for the realisation of many experiments in quantum information science. Here we demonstrate a promising approach to incorporate Eu ions into diamond, providing a means to harness the exceptional characteristics of both lanthanides and diamond in a single material. Polyelectrolytes are used to electrostatically assemble Eu(III) chelate molecules on diamond and subsequently chemical vapour deposition is employed for the diamond growth. Fluorescence measurements show that the Eu atoms retain the characteristic optical signature of Eu(III) upon incorporation into the diamond lattice. Computational modelling supports the experimental findings, corroborating that Eu(III) in diamond is a stable configuration. The formed defects demonstrate the outstanding chemical control over the incorporation of impurities into diamond enabled by the electrostatic assembly together with chemical vapour deposition growth.