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RESEARCH PRODUCT
Intersystem crossing in Fe(II) coordination compounds
Christian HennenHartmut SpieringSonja DeisenrothPeter AdlerAndreas VefAndreas HauserPhilipp Gütlichsubject
Arrhenius equationNuclear and High Energy Physicseducation.field_of_studyChemistryPopulationCondensed Matter PhysicsInternal conversion (chemistry)PhotochemistryMolecular physicsAtomic and Molecular Physics and OpticsVibronic couplingsymbols.namesakeIntersystem crossingReaction rate constantsymbolsRelaxation (physics)Physical and Theoretical ChemistryeducationQuantum tunnellingdescription
Fe(II) spin-crossover systems can be quantitatively converted from the low-spin (LS) to the high-spin (HS) state well below the thermal transition temperature by irradiating either into the metal-ligand charge transfer or d-d absorption bands, and even in low-spin systems a transient population of the HS state can be achieved. This fact can be made use of to determine HS → LS relaxation rate constants for a wide variety of Fe(II) spin-crossover and low-spin systems. The HS → LS relaxation shows strong deviations from an Arrhenius behaviour, with nearly temperature-independent tunnelling below ∼70 K and a thermally activated process above ∼100 K. The range of more than 12 orders of magnitude in the low temperature tunnelling rate constant can be understood in terms of a non-adiabatic multiphonon process, where in the strong vibronic coupling limit an inverse energy gap law holds.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 1994-12-01 | Hyperfine Interactions |