arXiv subjects

Harry L Anderson

Publications and source records attributed to Harry L Anderson.

2 recordsLinked to original sources

arXiv2026

Electronic dynamics in long linear and cyclic polyynes towards the carbyne limit

Carbyne-the one-dimensional sp-hybridised allotrope of carbon-has long been predicted to exhibit unique properties, yet its synthesis remains elusive. To probe its behaviour, finite sp-carbon chains such as cumulenes and polyynes have been studied, but work to date has focused almost exclusively on short, linear systems far from the infinite carbyne limit and without considering topology. Here, we investigate long (48-carbon) linear and cyclic polyynes using steady-state and ultrafast, temperature- and polarization-resolved optical and vibrational spectroscopy. We find highly delocalized ground states in both topologies, with Peierls distortions markedly weaker than in short chains. In contrast, excited states undergo rapid self-localisation, with the localisation pathway and subsequent intersystem crossing strongly dependent on chain length and topology. Unlike shorter polyynes, excited-state structural rearrangements are minimal, and comparison with theoretical predictions shows that properties, such as Huang-Rhys factors, have plateaued by 48 carbons. Our results reveal how topology influences the electronic dynamics of long polyynes and refines our understanding of sp-carbon systems approaching the carbyne limit

cond-mat.mes-hall↗

arXiv2025

Programmable self-assembly for scalable molecular electronic architectures

Molecular electronics and other technologies whose components comprise individual molecules have been pursued for half a century because the molecular scale represents the limit of miniaturisation of objects whose structure is tuneable for function. Despite the promise, practical progress has been hindered by the lack of methodologies for directed assembly of arbitrary structures applicable at the molecular scale. DNA nanotechnology is an emerging framework that uses programmed synthetic oligomers to encode the design of self-assembling structures with atomic precision at the nanoscale. Here, we leverage DNA-directed self-assembly to construct single-molecule electrical transport devices in high yield, precisely positioning a metal-porphyrin between two 60 nm gold nanoparticles. Following deposition on SiO2 substrates, we image and establish electrical contact via established nanofabrication techniques. Each step of the process has a high success rate and we demonstrate device yields dramatically better than is possible using conventional approaches. Our approach is inherently scalable and adaptable to devices incorporating multiple heterogenous functional molecular components, finally offering a realistic framework for the realisation of classical and quantum molecular technologies.

cond-mat.mes-hall↗