Hans Hofsäss | Searcharxiv

arXiv2026

Towards quantitative Low Energy Ion Scattering on CaSiO$_3$ from Comparison to Multiple-Scattering-Resolved Dynamical Binary Collision Approximation Simulations

We perform Low Energy Ion Scattering with He ions ranging in energy from 1 keV to 3 keV on CaSiO$_3$ using a commercial electrostatic detector system and determine the charge fraction of scattered ions from comparison with Binary Collision Approximation simulations. The simulations take composition changes due to surface cleaning Xe sputtering into account. Scattered He particles are separated in the simulation into single, dual, and multiple scattering trajectories. We find that the charge fraction of single and dual scattered He is about 10 times higher than the one for multiple collisions. Our results show that the charge fraction of scattered He can be reliably extracted for different scattering regimes and that for a given He incidence energy, the entire scattered He spectrum can be modeled with only few constant parameters.

cond-mat.mtrl-sci↗

arXiv2016

Single-atom spectroscopy of phosphorus dopants implanted into graphene

One of the keys behind the success of the modern semiconductor technology has been the ion implantation of silicon, which allows its electronic properties to be tailored. For similar purposes, heteroatoms have been introduced into carbon nanomaterials both during growth and using post-growth methods. However, due to the nature of the samples, it has been challenging to determine whether the heteroatoms have been incorporated into the lattice as intended, with direct observations so far being limited to N and B dopants, and incidental Si impurities. Furthermore, ion implantation of these materials is more challenging due to the requirement of very low ion energies and atomically clean surfaces. Here, we provide the first atomic-resolution imaging and electron energy loss spectroscopy (EELS) evidence of phosphorus atoms incorporated into the graphene lattice by low-energy ion irradiation. The measured P L-edge response of an single-atom EELS spectrum map shows excellent agreement with an ab initio spectrum simulation, conclusively identifying the P in a buckled substitutional configuration. Our results demonstrate the viability of phosphorus as a lattice dopant in $sp^2$-bonded carbon structures and provide its unmistakeable fingerprint for further studies.

cond-mat.mtrl-sci↗