Ultrafast nonadiabatic dynamics probed by nitrogen K-edge absorption spectroscopy

2020 ◽  
Vol 22 (5) ◽  
pp. 2667-2676 ◽  
Author(s):  
T. Northey ◽  
J. Norell ◽  
A. E. A. Fouda ◽  
N. A. Besley ◽  
M. Odelius ◽  
...  
Keyword(s):  
Excited States ◽  
Quantum Dynamics ◽  
Degrees Of Freedom ◽  
Nonadiabatic Dynamics ◽  
Edge Structure ◽  
Strongly Coupled ◽  
X Ray ◽  
Electronically Excited ◽  
Dynamics Simulations ◽  
X Ray Absorption

Quantum dynamics simulations are used to simulate the ultrafast X-ray Absorption Near-Edge Structure (XANES) spectra of photoexcited pyrazine including two strongly coupled electronically excited states and four normal mode degrees of freedom.

High-Fidelity First Principles Nonadiabaticity: Diabatization, Analytic Representation of Global Diabatic Potential Energy Matrices, and Quantum Dynamics

2021 ◽  
Author(s):  
Yafu Guan ◽  
Changjian Xie ◽  
David R. Yarkony ◽  
Hua Guo
Keyword(s):  
Potential Energy ◽  
Excited States ◽  
First Principles ◽  
Quantum Dynamics ◽  
Chemical Processes ◽  
High Fidelity ◽  
Nonadiabatic Dynamics ◽  
Electronically Excited States ◽  
Electronically Excited ◽  
Oppenheimer Approximation

Nonadiabatic dynamics, which goes beyond the Born-Oppenheimer approximation, has increasingly been shown to play an important role in chemical processes, particularly those involving electronically excited states. Understanding multistate dynamics requires...

scholarly journals X-ray transient absorption reveals the 1Au (nπ*) state of pyrazine in electronic relaxation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Valeriu Scutelnic ◽  
Shota Tsuru ◽  
Mátyás Pápai ◽  
Zheyue Yang ◽  
Michael Epshtein ◽  
...  
Keyword(s):  
Electronic Excitation ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Electronic Relaxation ◽  
Nonadiabatic Dynamics ◽  
X Ray ◽  
Organic Chromophores ◽  
Dynamics Simulations ◽  
X Ray Absorption ◽  
Structure Calculations

AbstractElectronic relaxation in organic chromophores often proceeds via states not directly accessible by photoexcitation. We report on the photoinduced dynamics of pyrazine that involves such states, excited by a 267 nm laser and probed with X-ray transient absorption spectroscopy in a table-top setup. In addition to the previously characterized 1B2u (ππ*) (S2) and 1B3u (nπ*) (S1) states, the participation of the optically dark 1Au (nπ*) state is assigned by a combination of experimental X-ray core-to-valence spectroscopy, electronic structure calculations, nonadiabatic dynamics simulations, and X-ray spectral computations. Despite 1Au (nπ*) and 1B3u (nπ*) states having similar energies at relaxed geometry, their X-ray absorption spectra differ largely in transition energy and oscillator strength. The 1Au (nπ*) state is populated in 200 ± 50 femtoseconds after electronic excitation and plays a key role in the relaxation of pyrazine to the ground state.

scholarly journals X-Ray Transient Absorption Reveals the 1Au (Nπ*) State of Pyrazine in Electronic Relaxation

2021 ◽  
Author(s):  
Valeriu Scutelnic ◽  
Shota Tsuru ◽  
Mátyás Imre Pápai ◽  
Zheyue Yang ◽  
Michael Epshtein ◽  
...  
Keyword(s):  
Electronic Excitation ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Electronic Relaxation ◽  
Nonadiabatic Dynamics ◽  
X Ray ◽  
Organic Chromophores ◽  
Dynamics Simulations ◽  
X Ray Absorption ◽  
Structure Calculations

Electronic relaxation in organic chromophores often proceeds via states not directly accessible by photoexcitation. We report on the photoinduced dynamics of pyrazine that involves such states, excited by a 267 nm laser and probed with X-ray transient absorption spectroscopy in a table-top setup. In addition to the previously characterized <sup>1</sup>B<sub>2u</sub> (ππ*) (S<sub>2</sub>) and <sup>1</sup>B<sub>3u</sub> (nπ*) (S<sub>1</sub>) states, the participation of the optically dark <sup>1</sup>A<sub>u</sub> (nπ*) state is assigned by a combination of experimental X-ray core-to-valence spectroscopy, electronic structure calculations, nonadiabatic dynamics simulations, and X-ray spectral computation. Despite <sup>1</sup>A<sub>u</sub> (nπ*) and <sup>1</sup>B<sub>3u</sub> (nπ*) states having similar energies at relaxed geometry, their X-ray absorption spectra differ largely in transition energy and oscillator strength. The <sup>1</sup>A<sub>u</sub> (nπ*) state is populated about 200 femtoseconds after electronic excitation and plays a key role in the relaxation of pyrazine to the ground state.

Re and Br X-ray Absorption Near-Edge Structure Study of the Ground and Excited States of [ReBr(CO)3(bpy)] Interpreted by DFT and TD-DFT Calculations

2013 ◽  
Vol 52 (10) ◽  
pp. 5775-5785 ◽  
Author(s):  
Stanislav Záliš ◽  
Chris J. Milne ◽  
Amal El Nahhas ◽  
Ana María Blanco-Rodríguez ◽  
Renske M. van der Veen ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Excited States ◽  
Structure Study ◽  
Edge Structure ◽  
X Ray ◽  
Td Dft ◽  
X Ray Absorption

scholarly journals X-Ray Transient Absorption Reveals the 1Au (Nπ*) State of Pyrazine in Electronic Relaxation

2021 ◽  
Author(s):  
Valeriu Scutelnic ◽  
Shota Tsuru ◽  
Mátyás Imre Pápai ◽  
Zheyue Yang ◽  
Michael Epshtein ◽  
...  
Keyword(s):  
Electronic Excitation ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Electronic Relaxation ◽  
Nonadiabatic Dynamics ◽  
X Ray ◽  
Organic Chromophores ◽  
Dynamics Simulations ◽  
X Ray Absorption ◽  
Structure Calculations

Electronic relaxation in organic chromophores often proceeds via states not directly accessible by photoexcitation. We report on the photoinduced dynamics of pyrazine that involves such states, excited by a 267 nm laser and probed with X-ray transient absorption spectroscopy in a table-top setup. In addition to the previously characterized <sup>1</sup>B<sub>2u</sub> (ππ*) (S<sub>2</sub>) and <sup>1</sup>B<sub>3u</sub> (nπ*) (S<sub>1</sub>) states, the participation of the optically dark <sup>1</sup>A<sub>u</sub> (nπ*) state is assigned by a combination of experimental X-ray core-to-valence spectroscopy, electronic structure calculations, nonadiabatic dynamics simulations, and X-ray spectral computation. Despite <sup>1</sup>A<sub>u</sub> (nπ*) and <sup>1</sup>B<sub>3u</sub> (nπ*) states having similar energies at relaxed geometry, their X-ray absorption spectra differ largely in transition energy and oscillator strength. The <sup>1</sup>A<sub>u</sub> (nπ*) state is populated about 200 femtoseconds after electronic excitation and plays a key role in the relaxation of pyrazine to the ground state.

scholarly journals X-Ray Transient Absorption Reveals the 1Au (Nπ*) State of Pyrazine in Electronic Relaxation

2021 ◽  
Author(s):  
Valeriu Scutelnic ◽  
Shota Tsuru ◽  
Mátyás Imre Pápai ◽  
Zheyue Yang ◽  
Michael Epshtein ◽  
...  
Keyword(s):  
Electronic Excitation ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Electronic Relaxation ◽  
Nonadiabatic Dynamics ◽  
X Ray ◽  
Organic Chromophores ◽  
Dynamics Simulations ◽  
X Ray Absorption ◽  
Structure Calculations

Electronic relaxation in organic chromophores often proceeds via states not directly accessible by photoexcitation. We report on the photoinduced dynamics of pyrazine that involves such states, excited by a 267 nm laser and probed with X-ray transient absorption spectroscopy in a table-top setup. In addition to the previously characterized <sup>1</sup>B<sub>2u</sub> (ππ*) (S<sub>2</sub>) and <sup>1</sup>B<sub>3u</sub> (nπ*) (S<sub>1</sub>) states, the participation of the optically dark <sup>1</sup>A<sub>u</sub> (nπ*) state is assigned by a combination of experimental X-ray core-to-valence spectroscopy, electronic structure calculations, nonadiabatic dynamics simulations, and X-ray spectral computation. Despite <sup>1</sup>A<sub>u</sub> (nπ*) and <sup>1</sup>B<sub>3u</sub> (nπ*) states having similar energies at relaxed geometry, their X-ray absorption spectra differ largely in transition energy and oscillator strength. The <sup>1</sup>A<sub>u</sub> (nπ*) state is populated about 200 femtoseconds after electronic excitation and plays a key role in the relaxation of pyrazine to the ground state.

scholarly journals Probing spin–vibronic dynamics using femtosecond X-ray spectroscopy

2016 ◽  
Vol 194 ◽  
pp. 731-746 ◽  
Author(s):  
T. J. Penfold ◽  
M. Pápai ◽  
T. Rozgonyi ◽  
K. B. Møller ◽  
G. Vankó
Keyword(s):  
Excited State ◽  
Degrees Of Freedom ◽  
Free Electrons ◽  
Edge Structure ◽  
Pump Probe ◽  
X Ray ◽  
Wavepacket Dynamics ◽  
Methyl Imidazole ◽  
Probe Spectroscopy ◽  
X Ray Absorption

Ultrafast pump-probe spectroscopy within the X-ray regime is now possible owing to the development of X-ray Free Electrons Lasers (X-FELs) and is opening new opportunities for the direct probing of femtosecond evolution of the nuclei, the electronic and spin degrees of freedom. In this contribution we use wavepacket dynamics of the photoexcited decay of a new Fe(ii) complex, [Fe(bmip)2]2+ (bmip = 2,6-bis(3-methyl-imidazole-1-ylidine)pyridine), to simulate the experimental observables associated with femtosecond Fe K-edge X-ray Absorption Near-Edge Structure (XANES) and X-ray emission (XES) spectroscopy. We show how the evolution of the nuclear wavepacket is translated into the spectroscopic signal and the sensitivity of these approaches for following excited state dynamics.

scholarly journals X-Ray Transient Absorption Reveals the 1Au (Nπ*) State of Pyrazine in Electronic Relaxation

2021 ◽  
Author(s):  
Valeriu Scutelnic ◽  
Shota Tsuru ◽  
Mátyás Imre Pápai ◽  
Zheyue Yang ◽  
Michael Epshtein ◽  
...  
Keyword(s):  
Electronic Excitation ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Electronic Relaxation ◽  
Nonadiabatic Dynamics ◽  
X Ray ◽  
Organic Chromophores ◽  
Dynamics Simulations ◽  
X Ray Absorption ◽  
Structure Calculations

Electronic relaxation in organic chromophores often proceeds via states not directly accessible by photoexcitation. We report on the photoinduced dynamics of pyrazine that involves such states, excited by a 267 nm laser and probed with X-ray transient absorption spectroscopy in a table-top setup. In addition to the previously characterized <sup>1</sup>B<sub>2u</sub> (ππ*) (S<sub>2</sub>) and <sup>1</sup>B<sub>3u</sub> (nπ*) (S<sub>1</sub>) states, the participation of the optically dark <sup>1</sup>A<sub>u</sub> (nπ*) state is assigned by a combination of experimental X-ray core-to-valence spectroscopy, electronic structure calculations, nonadiabatic dynamics simulations, and X-ray spectral computation. Despite <sup>1</sup>A<sub>u</sub> (nπ*) and <sup>1</sup>B<sub>3u</sub> (nπ*) states having similar energies at relaxed geometry, their X-ray absorption spectra differ largely in transition energy and oscillator strength. The <sup>1</sup>A<sub>u</sub> (nπ*) state is populated about 200 femtoseconds after electronic excitation and plays a key role in the relaxation of pyrazine to the ground state.

Chemical and orientational imaging of polymeric samples

1994 ◽  
Vol 52 ◽  
pp. 68-69
Author(s):  
H. Ade ◽  
B. Hsiao ◽  
G. Mitchell ◽  
E. Rightor ◽  
A. P. Smith ◽  
...  
Keyword(s):  
Ethylene Terephthalate ◽  
National Laboratory ◽  
Brookhaven National Laboratory ◽  
Carbonyl Groups ◽  
Aromatic Rings ◽  
Edge Structure ◽  
X Ray ◽  
Scanning Transmission ◽  
Polymeric Samples ◽  
X Ray Absorption

We have used the Scanning Transmission X-ray Microscope at beamline X1A (X1-STXM) at Brookhaven National Laboratory (BNL) to acquire high resolution, chemical and orientation sensitive images of polymeric samples as well as point spectra from 0.1 μm areas. This sensitivity is achieved by exploiting the X-ray Absorption Near Edge Structure (XANES) of the carbon K edge. One of the most illustrative example of the chemical sensitivity achievable is provided by images of a polycarbonate/pol(ethylene terephthalate) (70/30 PC/PET) blend. Contrast reversal at high overall contrast is observed between images acquired at 285.36 and 285.69 eV (Fig. 1). Contrast in these images is achieved by exploring subtle differences between resonances associated with the π bonds (sp hybridization) of the aromatic groups of each polymer. PET has a split peak associated with these aromatic groups, due to the proximity of its carbonyl groups to its aromatic rings, whereas PC has only a single peak.

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