The impact of spin–orbit coupling on fine-structure and spin polarisation in photoexcited porphyrin triplet states

Journal article

The photoexcited triplet states of porphyrins show great promise for applications in the fields of opto-electronics, photonics, molecular wires, and spintronics. The magnetic properties of porphyrin triplet states are most conveniently studied by time-resolved continuous wave and pulse electron spin resonance (ESR). This family of techniques is singularly able to probe small yet essential details of triplet states: zero-field splittings, g-anisotropy, spin polarisation, and hyperfine interactions. These characteristics are linked to spin–orbit coupling (SOC) which is known to have a strong influence on photophysical properties such as intersystem crossing rates. The present study explores SOC effects induced by the presence of Pd2+ in various porphyrin architectures. In particular, the impact of this relativistic interaction on triplet state fine-structure and spin polarisation is investigated. These properties are probed using time-resolved ESR complemented by electron-nuclear double resonance. The findings of this study could influence the future design of molecular spintronic devices. The Pd2+ ion may be incorporated into porphyrin molecular wires as a way of controlling spin polarisation.

Authors: Moise, G; Redman, AJ; Richert, S; Myers, WK; Bulut, I

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Elsevier
• Journal: Journal of Magnetic Resonance
• Volume: 355
• Article number: 107546
• Place of publication: United States
• Publication date: 2023-09-06
• Acceptance date: 2023-08-31
• DOI: 10.1016/j.jmr.2023.107546
• EISSN: 1096-0856
• ISSN: 1090-7807
• Pmid: 37797559
• Language: English
• Keywords: fine-structure; palladium porphyrin; zero-field splitting; spintronics; transient ESR; triplet state; spin–orbit coupling; spin polarisation