posted on 2023-01-04, 17:06authored byVince
M. Hipwell, Alana Rose Meyer, Miguel A. Garcia-Garibay
Triplet acyl–alkyl radical
pairs generated by pulsed laser
excitation within the constraints of their nanocrystalline ketone
precursors were recently introduced as a potential platform for the
robust and repeated instantiation of spin qubit pairs for applications
in quantum information science. Here, we report the transient spectroscopy
of a series of nanocrystalline trityl–alkyl and trityl–aryl
ketones capable of generating correlated triplet radical pairs with
persistent triphenylmethyl radicals forced to remain within bonding
distances of highly reactive acyl radicals. Whereas triplet trityl–acyl
radical pairs decay by competing product-forming decarbonylation and
intersystem crossing, triplet trityl–benzoyl radical pairs
have lifetimes of up to ca. 4 ms and exclusively regenerate the starting
ketone. We propose that these long lifetimes are the result of the
short inter-radical distances and the colinear orientation of the
two singly occupied orbitals, which are expected to result in large
singlet–triplet energy gaps, large zero-field splitting parameters,
and a poor geometry for spin-obit coupling. Ketones generating trityl–benzoyl
radical pairs demonstrate promising performance along multiple dimensions
that are crucial for quantum information science.