Generation and Transfer of Triplet Electron Spin Polarization at Solid-Liquid Interface

07 March 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


The photoexcited triplet state of dyes can generate highly polarized electron spins for sensing and dynamic nuclear polarization. However, while triplets exhibit long spin-lattice relaxation times (T1) on the microsecond scale in solids, the polarization quickly relaxes on the nanosecond scale in solution due to the rotational motion of chromophores. Here, we report that the immobilization of dye molecules on a solid surface allows molecular contact with a liquid while maintaining high polarization and long T1 as in a solid. By adsorbing anionic porphyrins on cationic mesoporous silica gel, porphyrin triplets exhibit high polarization and long T1 at the solid-liquid interface of silica and toluene. Furthermore, porphyrin triplets on the solid surface can exchange spin polarization with TEMPO radicals in solution. This simple and versatile method using the solid-liquid interface will open the way for utilizing the photo-induced triplet spin polarization in solution, which has been mainly limited to the solid-state.


dynamic electron polarization
photoexcited triplet state
solid-liquid interface

Supplementary materials

Supporting Information
Experimental details, absorption and fluorescence spectra, confocal microscopy images, SEM images, BET plots, cw-ESR spectra, and transient absorption spectra and decays.


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