Electron beams in transmission electron microscopes are very attractive to engineer and pattern graphene toward all-carbon device fabrication. The use of condensed beams typically used for sequential raster imaging is particularly exciting since they potentially provide high degrees of precision. However, technical difficulties, such as the formation of electron beam induced deposits on sample surfaces, have hindered the development of this technique. We demonstrate how one can successfully use a condensed electron beam, either with or without C(s) correction, to structure graphene with sub-nanometer precision in a programmable manner. We further demonstrate the potential of the developed technique by combining it with an established route to engineer graphene nanoribbons to single-atom carbon chains.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1021/nn304256a | DOI Listing |
Med Phys
January 2025
Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, USA.
Background: A cylindrical free-air chamber, the Attix FAC, is used for absolute air-kerma measurements of low-energy photon beams at the University of Wisconsin Medical Radiation Research Center. Correction factors for air-kerma measurements of specific beams were determined in the 1990s. In order to measure air-kerma rates of beams in development, new correction factors must be computed.
View Article and Find Full Text PDFRadiat Res
January 2025
Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota.
Variable relative biological effectiveness (RBE) of carbon radiotherapy may be calculated using several models, including the microdosimetric kinetic model (MKM), stochastic MKM (SMKM), repair-misrepair-fixation (RMF) model, and local effect model I (LEM), which have not been thoroughly compared. In this work, we compared how these four models handle carbon beam fragmentation, providing insight into where model differences arise. Monoenergetic and spread-out Bragg peak carbon beams incident on a water phantom were simulated using Monte Carlo.
View Article and Find Full Text PDFMaterials (Basel)
January 2025
School of Civil Engineering and Architecture, Wuyi University, No. 358 Baihua Road, Wuyishan 354300, China.
The ruins of the Imperial City of the Minyue Kingdom were an important site of the Minyue Kingdom during the Han Dynasty. Characteristic bronze arrowheads unearthed from the East Gate, with their exquisite craftsmanship, provide important physical evidence for studying ancient bronze casting technology and the military activities of that time. However, there is still a lack of systematic research on the alloy composition, casting process, and chemical stability of these arrowheads in long-term burial environments.
View Article and Find Full Text PDFCancers (Basel)
January 2025
Intense Laser Irradiation Laboratory, National Institute of Optics, National Research Council of Italy, 56124 Pisa, Italy.
The use of very high energy electron (VHEE) beams, with energies between 50 and 400 MeV, has drawn considerable interest in radiotherapy due to their deep tissue penetration, sharp beam edges, and low sensitivity to tissue density. VHEE beams can be precisely steered with magnetic components, positioning VHEE therapy as a cost-effective option between photon and proton therapies. However, the clinical implementation of VHEE therapy (VHEET) requires advances in several areas: developing compact, stable, and efficient accelerators; creating sophisticated treatment planning software; and establishing clinically validated protocols.
View Article and Find Full Text PDFSci Rep
January 2025
Accelerator Operations and Technology Division, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM, 87545, USA.
The pursuit to operate photocathodes at high accelerating gradients to increase brightness of electron beams is gaining interests within the accelerator community, particularly for applications such as free electron lasers (FEL) and compact accelerators. Cesium telluride (CsTe) is a widely used photocathode material and it is presumed to offer resilience to higher gradients because of its wider band gap compared to other semiconductors. Despite its advantages, crucial material properties of CsTe remain largely unknown both in theory and experiments.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!