scholarly journals Ballistic ΔS=2 Intersystem Crossing in a Cobalt Cubane Following Ligand-Field Excitation Probed by Extreme Ultraviolet Spectroscopy

2021 ◽  
Author(s):  
Yusef Shari'ati ◽  
Josh Vura-Weis
Keyword(s):  
Excited State ◽  
Extreme Ultraviolet ◽  
Xanes Spectroscopy ◽  
Ligand Field ◽  
Ultraviolet Spectroscopy ◽  
Intersystem Crossing ◽  
Edge Structure ◽  
X Ray ◽  
Field Excitation ◽  
X Ray Absorption

Femtosecond M2,3-edge X-ray absorption near-edge structure (XANES) spectroscopy is used to probe the excited-state dynamics of the cobalt cubane [CoIII4O4](OAc)4(py)4 (OAc = acetate, py = pyridine), a model for water...

scholarly journals Ballistic ΔS=2 Intersystem Crossing in a Cobalt Cubane Following Ligand-Field Excitation Probed by Extreme Ultraviolet Spectroscopy

2021 ◽  
Author(s):  
Yusef Shari'ati ◽  
Josh Vura-Weis
Keyword(s):  
Excited State ◽  
Water Oxidation ◽  
Extreme Ultraviolet ◽  
Ligand Field ◽  
Ultraviolet Spectroscopy ◽  
Intersystem Crossing ◽  
Edge Structure ◽  
X Ray ◽  
Field Excitation ◽  
X Ray Absorption

Femtosecond M2,3-edge X-ray absorption near-edge structure (XANES) spectroscopy is used to probe the excited-state dynamics of the cobalt cubane [CoIII4O4](OAc)4(py)4 (OAc = acetate, py = pyridine), a model for water oxidation catalysts. After ligand-field excitation, intersystem crossing to a metal-centered quintet occurs in 38 fs. 30% of the hot quintet undergoes ballistic back-ISC directly to the singlet ground stat, with the remainder relaxing to a long-lived triplet.

Sub-100 Fs Intersystem Crossing to a Metal-Centered Triplet in Ni(II)OEP Observed with M-Edge XANES

2019 ◽  
Author(s):  
Elizabeth S. Ryland ◽  
Kaili Zhang ◽  
Josh Vura-Weis
Keyword(s):  
Excited State ◽  
Time Resolution ◽  
Transient Absorption ◽  
Extreme Ultraviolet ◽  
High Harmonic ◽  
Transient Absorption Spectroscopy ◽  
Intersystem Crossing ◽  
Edge Structure ◽  
State Spin ◽  
X Ray Absorption

Nickel porphyrins have been extenstively studied as photosensitizers due to their long-lived metal-centered excited states. The multiplicity of the (d,d) state, and/or the rate of intersystem crossing between singlet and triplet metal-centered states, has remained uncertain due to the spin-insensitivity of many spectral probes. In this work, we directly probe the metal 3d shell occupation of nickel(II) octaethylporphyrin (NiOEP) using femtosecond M2,3-edge X-ray absorption near-edge structure (XANES). A tabletop high-harmonic source is used to perform 400 nm pump, extreme-ultraviolet probe transient absorption spectroscopy with ~100 fs time resolution. Photoexcitation produces a (π,π*) state that evolves with a time constant of 48 fs to a vibrationally hot metal-centered triplet 3(d,d) excited state with a lifetime of 595 ps. The spin sensitivity of M-edge XANES allows the 3(d,d) state to be distinguished from a potential 1(d,d) state, as shown by charge transfer multiplet simulations and comparison to triplet nickel(II) oxide. Vibrational cooling of the hot triplet state occurs over tens of ps, with minimal change in the electronic structure of the nickel(II) center. No evidence of an LMCT or MLCT intermediate state is seen within the time resolution of the instrument, suggesting that if such a state exists in NiOEP it depopulates in <25 fs. Finally, this study demonstrates the ability of table high-harmonic XUV sources to measure excited-state spin transitions in molecular transition metal complexes.

Sub-100 Fs Intersystem Crossing to a Metal-Centered Triplet in Ni(II)OEP Observed with M-Edge XANES

2019 ◽  
Author(s):  
Elizabeth S. Ryland ◽  
Kaili Zhang ◽  
Josh Vura-Weis
Keyword(s):  
Excited State ◽  
Time Resolution ◽  
Transient Absorption ◽  
Extreme Ultraviolet ◽  
High Harmonic ◽  
Transient Absorption Spectroscopy ◽  
Intersystem Crossing ◽  
Edge Structure ◽  
State Spin ◽  
X Ray Absorption

Nickel porphyrins have been extenstively studied as photosensitizers due to their long-lived metal-centered excited states. The multiplicity of the (d,d) state, and/or the rate of intersystem crossing between singlet and triplet metal-centered states, has remained uncertain due to the spin-insensitivity of many spectral probes. In this work, we directly probe the metal 3d shell occupation of nickel(II) octaethylporphyrin (NiOEP) using femtosecond M2,3-edge X-ray absorption near-edge structure (XANES). A tabletop high-harmonic source is used to perform 400 nm pump, extreme-ultraviolet probe transient absorption spectroscopy with ~100 fs time resolution. Photoexcitation produces a (π,π*) state that evolves with a time constant of 48 fs to a vibrationally hot metal-centered triplet 3(d,d) excited state with a lifetime of 595 ps. The spin sensitivity of M-edge XANES allows the 3(d,d) state to be distinguished from a potential 1(d,d) state, as shown by charge transfer multiplet simulations and comparison to triplet nickel(II) oxide. Vibrational cooling of the hot triplet state occurs over tens of ps, with minimal change in the electronic structure of the nickel(II) center. No evidence of an LMCT or MLCT intermediate state is seen within the time resolution of the instrument, suggesting that if such a state exists in NiOEP it depopulates in <25 fs. Finally, this study demonstrates the ability of table high-harmonic XUV sources to measure excited-state spin transitions in molecular transition metal complexes.

scholarly journals Performance of secondary P-fertilizers in pot experiments analyzed by phosphorus X-ray absorption near-edge structure (XANES) spectroscopy

AMBIO ◽  
2017 ◽  
Vol 47 (S1) ◽  
pp. 62-72 ◽  
Author(s):  
Christian Vogel ◽  
Camille Rivard ◽  
Verena Wilken ◽  
Andreas Muskolus ◽  
Christian Adam
Keyword(s):  
Xanes Spectroscopy ◽  
Edge Structure ◽  
X Ray ◽  
Pot Experiments ◽  
X Ray Absorption ◽  
P Fertilizers

Antivitamins B12 in a Microdrop: The Excited-State Structure of a Precious Sample Using Transient Polarized X-ray Absorption Near-Edge Structure

2019 ◽  
Vol 10 (18) ◽  
pp. 5484-5489 ◽  
Author(s):  
Nicholas A. Miller ◽  
Lindsay B. Michocki ◽  
Roberto Alonso-Mori ◽  
Alexander Britz ◽  
Aniruddha Deb ◽  
...  
Keyword(s):  
Excited State ◽  
State Structure ◽  
Edge Structure ◽  
X Ray ◽  
X Ray Absorption

scholarly journals Ballistic excited state dynamics revealed by polarized fs-XANES

2019 ◽  
Vol 205 ◽  
pp. 05014 ◽  
Author(s):  
Roseanne J. Sension ◽  
Nicholas A. Miller ◽  
Aniruddha Deb ◽  
Roberto Alonso-Mori ◽  
James M. Glownia ◽  
...  
Keyword(s):  
Excited State ◽  
Time Resolved ◽  
Edge Structure ◽  
X Ray ◽  
Excited State Dynamics ◽  
X Ray Absorption

Polarized time-resolved X-ray absorption near edge structure (XANES) is used to characterize the sequential ballistic excited state dynamics of two B12 vitamers: cyanocobalamin and adenosylcobalamin. Excitation at 550 nm and 365 nm is used to resolve axial and equatorial contributions to the excited state dynamics.

Phosphorus K-edge XANES spectroscopy has probably often underestimated iron oxyhydroxide-bound P in soils

2018 ◽  
Vol 25 (6) ◽  
pp. 1736-1744 ◽  
Author(s):  
Jörg Prietzel ◽  
Wantana Klysubun
Keyword(s):  
Linear Combination ◽  
Xanes Spectroscopy ◽  
Organic P ◽  
Iron Oxyhydroxide ◽  
Edge Structure ◽  
X Ray ◽  
Soil P ◽  
P Sorption ◽  
Fe Oxyhydroxides ◽  
X Ray Absorption

Phosphorus (P) K-edge X-ray absorption near-edge structure (XANES) spectra of orthophosphate (oPO4) bound to soil FeIII minerals (e.g. ferrihydrite, goethite) show a pre-edge signal at 2148–2152 eV. It is unknown whether organic P bound to FeIII oxyhydroxides also show this feature. Otherwise, Fe-bound soil P may be underestimated by P K-edge XANES spectroscopy, because a large portion of Fe oxyhydroxide-bound P in soils is organic P. K-edge XANES spectra were obtained for different organic P compounds present in soils [inositol hexaphosphate (IHP), glucose-6-phosphate (G6P), adenosine triphosphate (ATP)] after sorption to ferrihydrite or goethite and compared with spectra of oPO4 adsorbed to these minerals. P sorption to ferrihydrite increased in the sequence IHP ≪ G6P < oPO4 < ATP. P sorption to goethite increased in the sequence G6P < oPO4 ≪ ATP = IHP. Pre-edge signals in P K-edge XANES spectra of organic P adsorbed to Fe oxyhydroxides were markedly smaller compared with those of oPO4 adsorbed to these minerals and absent for FeIII oxyhydroxide-bound ATP as well as goethite-bound IHP. Linear combination fitting (LCF) performed on spectra of IHP, G6P or ATP adsorbed to ferrihydrite or goethite, using only spectra of FeIII oxyhydroxide-bound oPO4 as reference compounds for Fe-bound P, erroneously assigned >93% (ferrihydrite) or >41% (goethite) of Fe-bound P to non-Fe-bound P species. Inclusion of FeIII oxyhydroxide-bound IHP as reference compounds markedly increased the recovery of oxyhydroxide-bound organic P. Thus, Fe-bound soil P has probably often been underestimated by LCF in soil XANES studies where IHP adsorbed to ferrihydrite and to goethite were not included as reference compounds.

Sign in / Sign up

Export Citation Format

Share Document