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Updated: Apr 26, 2026

Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser
Published on: June 28, 2018
Breaking the semi-quinoid structure: spin-switching from strongly coupled singlet to polarized triplet state
Prince Ravat1, Yoshio Teki, Yoshikazu Ito
1Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz (Germany).
Abstract:
2,7-TMPNO (4,5,9,10-tetramethoxypyrene-2,7-bis(tert-butylnitroxide)) was found to exist in semi-quinoid form with unprecedented strong intramolecular magnetic exchange interaction of 2 J/kB = 1185 K operating over a distance of 10 Å. Structural transformations with the activation energy of ΔEeq = 949 K were observed by varying the temperature, from more quinoid structure at low temperature to more biradicaloid structure at higher temperature. Moreover, this molecule undergoes a transient spin transition from singlet to polarized triplet state upon photoexcitation revealed by TREPR spectroscopy. The spin Hamiltonian parameters were determined to be S = 1, g = 2.0065, D = -0.0112 cm(-1), and E = -0.0014 cm(-1) by spectral simulation with the hybrid Eigenfield/exact diagonalization method.
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