Picosecond x-ray absorption spectroscopy of a photoinducediron(II) spin crossover reaction in solution
In this study, we perform steady-state and time-resolved X-ray absorption spectroscopy (XAS) on the iron K-edge of [Fe(tren(py)3)](PF6)2 dissolved in acetonitrile solution. Static XAS measurements on the low-spin parent compound and its high-spin analogue, [Fe(tren(6-Me-py)3)](PF6)2, reveal distinct spectroscopic signatures for the two spin states in the X-ray absorption near-edge structure (XANES) and in the X-ray absorption fine structure (EXAFS). For the time-resolved studies, 100 fs, 400 nm pump pulses initiate a charge-transfer transition in the low-spin complex. The subsequent electronic and geometric changes associated with the formation of the high-spin excited state are probed with 70 ps, 7.1 keV, tunable X-ray pulses derived from the Advanced Light Source (ALS). Modeling of the transient XAS data reveals that the average iron-nitrogen (Fe-N) bond is lengthened by 0.21 (0.03 Angstrom) in the high-spin excited state relative to the ground state within 70 ps. This structural modification causes a change in the metal-ligand interactions as reflected by the altered density of states of the unoccupied metal orbitals. Our results constitute the first direct measurements of the dynamic atomic and electronic structural rearrangements occurring during a photo induced FeII spin crossover reaction in solution via picosecond X-ray absorption spectroscopy.
- Research Organization:
- Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
- Sponsoring Organization:
- USDOE Director. Office of Science. Office of Basic EnergySciences. Materials Science and Engineering Division, Chemical SciencesGeosciences and Biosciences Division. Michigan State University; MillerInstitute
- DOE Contract Number:
- AC02-05CH11231
- OSTI ID:
- 883783
- Report Number(s):
- LBNL--58982; BnR: KC0301030
- Journal Information:
- Journal of Physical Chemistry A, Journal Name: Journal of Physical Chemistry A Vol. 110
- Country of Publication:
- United States
- Language:
- English
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