arXiv subjects

Remco W. A. Havenith

Publications and source records attributed to Remco W. A. Havenith.

3 recordsLinked to original sources

arXiv2022

Towards detection of the molecular parity violation in chiral Ru(acac)$_3$ and Os(acac)$_3$

We present a theory-experiment investigation of the helically chiral compounds Ru(acac)$_3$ and Os(acac)$_3$ as candidates for the next-generation experiments for detection of molecular parity violation (PV) in vibrational spectra. We used state-of-the-art relativistic calculations to identify optimal vibrational modes with expected PV effects exceeding by up to two orders of magnitude the projected instrumental sensitivity of the experiment under construction at the Laboratoire de Physique des Lasers in Paris. High-resolution measurements of the vibrational spectrum of Ru(acac)$_3$ carried out as the first steps towards the planned experiment are presented.

physics.chem-ph↗

arXiv2018

Identification and tunable optical coherent control of transition-metal spins in silicon carbide

Color centers in wide-bandgap semiconductors are attractive systems for quantum technologies since they can combine long-coherent electronic spin and bright optical properties. Several suitable centers have been identified, most famously the nitrogen-vacancy defect in diamond. However, integration in communication technology is hindered by the fact that their optical transitions lie outside telecom wavelength bands. Several transition-metal impurities in silicon carbide do emit at and near telecom wavelengths, but knowledge about their spin and optical properties is incomplete. We present all-optical identification and coherent control of molybdenum-impurity spins in silicon carbide with transitions at near-infrared wavelengths. Our results identify spin $S=1/2$ for both the electronic ground and excited state, with highly anisotropic spin properties that we apply for implementing optical control of ground-state spin coherence. Our results show optical lifetimes of $\sim$60 ns and inhomogeneous spin dephasing times of $\sim$0.3 $μ$s, establishing relevance for quantum spin-photon interfacing.

cond-mat.mtrl-sci↗

arXiv2016

Control of Intramolecular Electron Transfer in Perylene Dihydrazides and Perylene Diimides: A Comparative Study by Time-Resolved Spectroscopy

Electron transfer (ET) in molecular donor-acceptor dye systems is crucial for charge transport in organic semiconductors. Classically, ET rates should decrease with increasing donor-acceptor distance while the microscopic mechanism is more complex and shows intricate dependencies on the excitation conditions. In this paper, we introduce highly soluble N,N'-dialkyl perylene dihydrazides (PDH) - perylene dyes with a dialkylamino -NR$_2$ donor functionality directly bonded to both of their imide nitrogen atoms. We compare the PDH electron-transfer dynamics with a group of classical N,N'-bisalkylperylene diimides (PDI) equipped with a -NR$_2$ donor linked to the PDI acceptor core via a varying number of alkylene -(CH$_2$)- spacer groups, thus at distinctively different distance. Special physicochemical design features of our study objects include: i) amine moieties as donor group to minimize spin-orbit coupling; ii) substitution solely at both imide positions to avoid major impact on HOMO and LUMO levels and distortions of the PDI backbone; iii) control of donor-acceptor separation by non-conjugated alkylene groups to exclude any additional effects due to delocalized $π$ electron systems. All materials show non-single-exponential photoluminescence decay dynamics. A rate equation analysis supported by electrochemical and absolute photoluminescence efficiency measurements yields evidence for efficient intersystem-crossing without heavy elements and reveals that the charge-transfer efficiency across the intramolecular interface strongly depends on the surplus excitation energy.

physics.chem-ph↗