TY - JOUR
T1 - Femtosecond Extreme Ultraviolet Spectroscopy of an Iridium Photocatalyst Reveals Oxidation State and Ligand Field Specific Dynamics
AU - Leahy, Clare A.
AU - Vura-Weis, Josh
N1 - Funding Information:
The transient XUV instrument, including the nonlinear optical parametric amplifier, was built with partial funding from the Air Force Office of Scientific Research under AFOSR Awards No. FA9550-14-1-0314 and FA9550-18-1-0293. We thank Dr. Michael Berman and AFOSR for their support of our work, which laid the foundation for this project. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0018904. We are grateful to Dr. Frank de Groot for discussion on analysis.
Publisher Copyright:
© 2022 American Chemical Society. All rights reserved.
PY - 2022/12/22
Y1 - 2022/12/22
N2 - Femtosecond X-ray absorption spectroscopy at the Ir O3-edge and N6,7-edges is performed on the photocatalyst iridium(III) tris(2-phenylpyridine), Ir(III)(ppy)3using a tabletop high-harmonic source. Extreme ultraviolet (XUV) absorption between 44 and 76 eV measures transitions from the Ir 5p3/2and 4f5/2,7/2core to 5d valence orbitals, and the position of these spectral features is shown to be sensitive to the oxidation state and ligand field of the metal center. Upon excitation of the singlet metal-to-ligand charge transfer (1MLCT) band at 400 nm, a shift in the spectra due to the formation of the Ir(IV) center is observed, as is the creation of a new spectral feature corresponding to transitions into the t2ghole. Vibrational cooling of the MLCT state on the 3 and 16 ps time scales is measured as changes in the intensity of the transient features. This work establishes XUV spectroscopy as a useful tool for measuring the electronic structure of third row transition metal photosensitizers and catalysts at ultrafast time scales.
AB - Femtosecond X-ray absorption spectroscopy at the Ir O3-edge and N6,7-edges is performed on the photocatalyst iridium(III) tris(2-phenylpyridine), Ir(III)(ppy)3using a tabletop high-harmonic source. Extreme ultraviolet (XUV) absorption between 44 and 76 eV measures transitions from the Ir 5p3/2and 4f5/2,7/2core to 5d valence orbitals, and the position of these spectral features is shown to be sensitive to the oxidation state and ligand field of the metal center. Upon excitation of the singlet metal-to-ligand charge transfer (1MLCT) band at 400 nm, a shift in the spectra due to the formation of the Ir(IV) center is observed, as is the creation of a new spectral feature corresponding to transitions into the t2ghole. Vibrational cooling of the MLCT state on the 3 and 16 ps time scales is measured as changes in the intensity of the transient features. This work establishes XUV spectroscopy as a useful tool for measuring the electronic structure of third row transition metal photosensitizers and catalysts at ultrafast time scales.
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U2 - 10.1021/acs.jpca.2c05562
DO - 10.1021/acs.jpca.2c05562
M3 - Article
C2 - 36480809
AN - SCOPUS:85143876788
SN - 1089-5639
VL - 126
SP - 9510
EP - 9518
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 50
ER -