Article
Chemistry, Multidisciplinary
Shuyi Liu, Adnan Hammud, Martin Wolf, Takashi Kumagai
Summary: The research demonstrates a method to significantly enhance Raman scattering by forming atomic point contact (APC), thereby detecting phonons on the silicon surface, and shows the chemical sensitivity of APC-TERS, expanding the applicability of TERS.
Review
Chemistry, Physical
Todd H. Lewis, Bo Zhang
Summary: Closed-bipolar electrochemical imaging (c-BPI) solves the tradeoff problem between optical response, spatial resolution, and photon efficiency in electrochemical heterogeneity imaging by coupling optical and electrochemical signals. Considering the potential for sensing ultra-transient events, we focus on fluorescence as a useful tool in c-BPI and examine the advantages and challenges of electrofluorogenic reporting strategies, providing solutions through direct and indirect approaches for electrochemical fluorescence imaging in closed-bipolar sensing systems.
CURRENT OPINION IN ELECTROCHEMISTRY
(2023)
Article
Chemistry, Physical
J. C. Mahato, Debolina Das, Arindam Pal, Prabir Pal, B. N. Dev
Summary: Epitaxial gamma-FeSi2 and CoSi2 nanostructures grown on a vicinal Si(1 1 1)-7 x 7 surface have been investigated, revealing nanowires and nanoislands which could potentially find applications in nanoscale devices.
APPLIED SURFACE SCIENCE
(2022)
Article
Chemistry, Multidisciplinary
Yidi Shen, Sergey I. Morozov, Kun Luo, Qi An, William A. Goddard III
Summary: This study investigates the mechanism of the Si(111)-7 x 7 surface reconstruction using molecular dynamics simulations. Two possible pathways for the formation of the 7 x 7 structure are identified, both involving the generation of dimers and bridged five-membered rings, and the stabilization of the triangular halves of the unit cell. The corner hole is formed from the joining of several five-member rings. The insertion of atoms to form a dumbbell configuration involves additional atom diffusion or rearrangement.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Yidi Shen, Sergey I. Morozov, Kun Luo, Qi An, William A. Goddard III
Summary: This study investigates the mechanism underlying the formation of the complex 7 x 7 structure on the Si(111) surface during annealing. Molecular dynamics simulations using a machine-learning force field reveal two possible pathways for the formation of the 7 x 7 structure, involving the creation of dimers and bridged five-membered rings. The findings have implications for manipulating the surface structure by introducing other atomic species.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Thermodynamics
R. A. Shaik, A. L. Kastengren, R. S. Tranter, P. T. Lynch
Summary: Gas densities behind incident and reflected shock waves were measured using x-ray absorption spectroscopy, revealing significant differences in densities as distance from the endwall increased. Abel inversion reconstruction allowed for time and radially resolved densities to be obtained, showing the presence of sidewall thermal boundary layers behind the reflected shock.
COMBUSTION AND FLAME
(2021)
Article
Environmental Sciences
Whitney Cowell, Elena Colicino, Xueying Zhang, Rachel Ledyard, Heather H. Burris, Michele R. Hacker, Itai Kloog, Allan Just, Robert O. Wright, Rosalind J. Wright
Summary: The study did not find a clear association between weekly exposure to PM2.5 and preterm birth, but in some cases, exposure to PM2.5 in gestational week 16 slightly increased the risk of preterm birth for female infants.
Article
Engineering, Chemical
Funda Arslan, Thomas Bohm, Jochen Kerres, Simon Thiele
Summary: This study demonstrates that confocal Raman microscopy can serve as a non-invasive measurement tool to investigate the status and progress of doping a membrane with phosphoric acid. The doping is shown to be a diffusion-limited process, resulting in a spatially inhomogeneous distribution of phosphoric acid unless doping is performed to saturation.
JOURNAL OF MEMBRANE SCIENCE
(2021)
Article
Chemistry, Analytical
Andrew D. Barr, Sam E. Rigby, Sam D. Clarke, Dain Farrimond, Andy Tyas
Summary: This paper presents the design of an experimental facility capable of providing definitive spatially and temporally resolved reflected pressure data in the extreme near field. The facility utilizes maraging steel pressure bars and specially designed strain gauges to increase measurement capacity and improve spatial resolution. This enables the validation of near-field transient effects predicted by numerical modeling and the development of effective blast mitigation methods.
Article
Chemistry, Physical
Tina Gaebel, Daniel Bein, Daniel Mathauer, Manuel Utecht, Richard Palmer, Tillmann Klamroth
Summary: This study utilized quantum chemical cluster models in conjunction with DFT and AIMD simulations to investigate STM manipulation experiments on PhCl on a Si(111)-7 X 7 surface. The experiments revealed nonlocal dissociation and desorption processes induced by electrons or holes, which were rationalized and explained using theoretical models. The coupling of ion resonances to nuclear degrees of freedom was also simulated, with predictions made regarding the lifetimes of cationic resonances. Additionally, transition-state theory calculations were validated against time-lapse STM experiments using the same cluster models.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Physics, Fluids & Plasmas
David Steuer, Henrik van Impel, Volker Schulz-von der Gathen, Marc Boeke, Judith Golda
Summary: Micro cavity plasma arrays have various applications, including treatment of volatile organic compounds and generation of new species. The focus has shifted to plasma catalysis, where catalytic surfaces are combined with plasmas. The key is generating reactive species like atomic oxygen within the plasma, typically measured using laser spectroscopic methods. In the case of micro plasma arrays, limited optical access led to the use of optical emission spectroscopy and helium state enhanced actinometry.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2023)
Article
Chemistry, Multidisciplinary
Daniele Capista, Luca Lozzi, Aniello Pelella, Antonio Di Bartolomeo, Filippo Giubileo, Maurizio Passacantando
Summary: Photodetectors based on vertical multi-walled carbon nanotube (MWCNT) film-Si heterojunctions are successfully achieved by growing MWCNTs on n-type Si substrates covered with Si3N4 layers. Spatially resolved photocurrent measurements demonstrate that higher photo detection is achieved in regions with thinner MWCNT film, resulting in nearly 100% external quantum efficiency. Therefore, a simple method utilizing scotch tape is proposed to tune the thickness and density of the as-grown MWCNT film, thereby enhancing the device photo-response.
Article
Environmental Sciences
Adam R. Vaughan, James D. Lee, Stefan Metzger, David Durden, Alastair C. Lewis, Marvin D. Shaw, Will S. Drysdale, Ruth M. Purvis, Brian Davison, C. Nicholas Hewitt
Summary: Measurements of nitrogen oxide fluxes over London using airborne eddy covariance showed high heterogeneity and strong diurnal variability, with central areas having the highest emission rates. Multiple emission sources, such as road transport and residential, commercial, and industrial combustion sources, likely contribute to the measured fluxes. Comparison with scaled National Atmospheric Emissions Inventory estimates revealed significant differences, with measured values up to 2 times higher in Central London.
ATMOSPHERIC CHEMISTRY AND PHYSICS
(2021)
Article
Chemistry, Analytical
Alexander Rusch, Thomas Roesgen
Summary: The COVID-19 pandemic has highlighted the significance of infection risk analysis and evaluation of ventilation systems in indoor environments based on air quality standards. This article presents a wireless array system consisting of 50 embedded sensor units, which can provide indoor climate metrics with configurable spatial and temporal resolutions. The system has proven effective in assessing indoor environments and has the capability to reconstruct three-dimensional air quality maps.
Article
Optics
Weibo Cheng, Zhaohui Wang, Xiaolong Liu, Ya Cheng, Pavel Polynkin
Summary: We present experimental findings on microvoid formation in bulk sapphire, achieved by illuminating the sample with near-infrared, simultaneously spatially and temporally focused (SSTF) laser beams in a single-shot. Compared to tightly focused femtosecond Gaussian and flattop beams, the SSTFs produce larger volume internal microvoids without cracks between interaction sites, which could have potential applications in volumetric data storage and the investigation of super-dense elemental phases in densified shells surrounding the microvoids.