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Updated: Sep 15, 2025

Patterning via Optical Saturable Transitions - Fabrication and Characterization
Published on: December 11, 2014
Mono- and sub-monolayer films of a highT1/2 spin-crossover molecule on HOPG: temperature- and light-driven spin-state
Jorge Torres1, Sangeeta Thakur1, Sascha Ossinger2
1Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
Abstract:
We investigated the properties of the[Fe{H2B(pz)(pypz)}2]spin-crossover complex deposited on highly oriented pyrolytic graphite (HOPG) by x-ray absorption spectroscopy in the temperature range from 10 to 350 Kfor sample thicknesses from 0.9(1) to 1.3(2) ML. The highest temperature at which light can excite the system to a long-lived metastable high-spin (HS) state (TLIESST) and the temperature at which a thermal spin transition occurs (T1/2) for the thin film samples are found as about 45 and 325 K, respectively, in agreement with the bulk values. The bulk phase has previously been studied by magnetic susceptibility measurements where it was found that two different polymorphic modifications exist. These findings suggest a potential correlation betweenTLIESSTand the highT1/2 from the different film thicknesses of the tridentate[Fe{H2B(pz)(pypz)}2]spin-crossover molecule, with thinner samples exhibiting lowerT1/2 values. Finally, the highest HS fraction achieved for[Fe{H2B(pz)(pypz)}2]is 0.77 for samples of 0.9(1) and 1.1(1) ML on HOPG at 10 Kand constant light irradiation.
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