Kämmerer Lea, Kämmerer Gérald, Gruber Manuel, Grunwald Jan, Lojewski Tobias, Mercadier Laurent, Le Guyader Loïc, Carley Robert, Carinan Cammille, Gerasimova Natalia, Hickin David, Van Kuiken Benjamin E, Mercurio Giuseppe, Teichmann Martin, Kuppusamy Senthil Kumar, Scherz Andreas, Ruben Mario, Sokolowski-Tinten Klaus, Eschenlohr Andrea, Ollefs Katharina, Schmitz-Antoniak Carolin, Tuczek Felix, Kratzer Peter, Bovensiepen Uwe, Wende Heiko
Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Duisburg 47057, Germany.
Institute for Inorganic Chemistry, Christian-Albrechts-University, Kiel 24098, Germany.
ACS Nano. 2024 Dec 24;18(51):34596-34605. doi: 10.1021/acsnano.4c05123. Epub 2024 Dec 12.
The tailoring of spin-crossover films has made significant progress over the past decade, mostly motivated by the prospect in technological applications. In contrast to spin-crossover complexes in solution, the investigation of the ultrafast switching in spin-crossover films has remained scarce. Combining the progress in molecule synthesis and film growth with the opportunities at X-ray free-electron lasers, we study the photoinduced spin-state switching dynamics of a molecular film at room temperature. The subpicosecond switching from the = 0 low-spin ground state to the = 2 high-spin state is monitored by analyzing the transient evolution of the Fe L X-ray absorption edge fine structure, i.e. element-specifically at the switching center of the Fe(II) complex. Our measurements show the involvement of an intermediate state in the switching. At large excitation fluences, the fraction of high-spin molecules saturates at ≈50%, which is likely due to molecule-molecule interaction within the film.
在过去十年中，自旋交叉薄膜的定制取得了重大进展，这主要是受技术应用前景的推动。与溶液中的自旋交叉配合物不同，对自旋交叉薄膜中超快开关的研究仍然很少。结合分子合成和薄膜生长方面的进展以及X射线自由电子激光带来的机遇，我们研究了室温下分子薄膜的光致自旋态开关动力学。通过分析Fe L X射线吸收边精细结构的瞬态演化，即元素特异性地在Fe(II)配合物的开关中心，监测到从S = 0低自旋基态到S = 2高自旋态的亚皮秒级开关。我们的测量结果表明开关过程涉及一个中间态。在大激发通量下，高自旋分子的比例在≈50%时饱和，这可能是由于薄膜内分子间的相互作用。
