Department of Chemistry, University of Tennessee, Knoxville, Tennessee, 37996, USA.
State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China.
Chemistry. 2019 Dec 10;25(69):15846-15857. doi: 10.1002/chem.201903635. Epub 2019 Nov 14.
Large separations between ground and excited magnetic states in single-molecule magnets (SMMs) are desirable to reduce the likelihood of spin reversal in the molecules. Spin-phonon coupling is a process leading to magnetic relaxation. Both the reversal and coupling, making SMMs lose magnetic moments, are undesirable. However, direct determination of large magnetic states separations (>45 cm ) is challenging, and few detailed investigations of the spin-phonon coupling have been conducted. The magnetic separation in Co(12-crown-4) (12-crown-4) (1) is determined and its spin-phonon coupling is probed by inelastic neutron scattering (INS) and far-IR spectroscopy. INS, using oriented single crystals, shows a magnetic transition at 49.4(1.0) cm . Far-IR reveals that the magnetic transition and nearby phonons are coupled, a rarely observed phenomenon, with spin-phonon coupling constants of 1.7-2.5 cm . The current work spectroscopically determines the ground-excited magnetic states separation in an SMM and quantifies its spin-phonon coupling, shedding light on the process causing magnetic relaxation.
在单分子磁体（SMM）中，希望地面和激发磁态之间有较大的分离，以降低分子中自旋反转的可能性。自旋-声子耦合是导致磁弛豫的过程。反转和耦合都会使 SMM 失去磁矩，这都是不希望发生的。然而，直接确定较大的磁态分离（>45cm）具有挑战性，并且对自旋-声子耦合的详细研究很少。通过非弹性中子散射（INS）和远红外光谱研究了[Co（12-冠-4）]（I）（12-冠-4）（1）中的磁分离及其自旋-声子耦合。使用取向单晶的 INS 显示出在 49.4（1.0）cm处的磁转变。远红外显示磁转变和附近的声子耦合，这是一种很少见的现象，自旋-声子耦合常数为 1.7-2.5cm。目前的工作通过光谱学确定了 SMM 中的基态与激发磁态之间的分离，并量化了其自旋-声子耦合，为导致磁弛豫的过程提供了线索。
