scholarly journals Sub-7-femtosecond conical-intersection dynamics probed at the carbon K-edge

Science ◽  
2021 ◽  
Vol 371 (6528) ◽  
pp. 489-494
Author(s):  
Kristina S. Zinchenko ◽  
Fernando Ardana-Lamas ◽  
Issaka Seidu ◽  
Simon P. Neville ◽  
Joscelyn van der Veen ◽  
...  
Keyword(s):  
Structural Dynamics ◽  
Transient Absorption ◽  
Broad Class ◽  
Transient Absorption Spectroscopy ◽  
Electronic Relaxation ◽  
Relaxation Dynamics ◽  
Spectral Separation ◽  
Electronically Excited ◽  
Short Time ◽  
Organic Chromophore

Conical intersections allow electronically excited molecules to return to their electronic ground state. Here, we observe the fastest electronic relaxation dynamics measured to date by extending attosecond transient-absorption spectroscopy (ATAS) to the carbon K-edge. We selectively launch wave packets in the two lowest electronic states (D0 and D1) of C2H4+. The electronic D1 → D0 relaxation takes place with a short time constant of 6.8 ± 0.2 femtoseconds. The electronic-state switching is directly visualized in ATAS owing to a spectral separation of the D1 and D0 bands caused by electron correlation. Multidimensional structural dynamics of the molecule are simultaneously observed. Our results demonstrate the capability to resolve the fastest electronic and structural dynamics in the broad class of organic molecules. They show that electronic relaxation in the prototypical organic chromophore can take place within less than a single vibrational period.

Electronic relaxation dynamics of PCDA-PDA studied by transient absorption spectroscopy

2016 ◽  
Vol 18 (33) ◽  
pp. 23096-23104 ◽  
Author(s):  
Joonyoung F. Joung ◽  
Junwoo Baek ◽  
Youngseo Kim ◽  
Songyi Lee ◽  
Myung Hwa Kim ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Electronic Relaxation ◽  
Relaxation Dynamics ◽  
Femtosecond Transient Absorption ◽  
Femtosecond Transient Absorption Spectroscopy ◽  
Thermochromic Properties

Spectroscopic signature of thermochromic properties of PCDA-PDA is revealed by femtosecond transient absorption spectroscopy.

Excited-State Dynamics in the RNA Nucleotide Uridine 5’-Monophosphate Investigated by Femtosecond Broadband Transient Absorption Spectroscopy

2019 ◽  
Author(s):  
Matthew M. Brister ◽  
Carlos Crespo-Hernández
Keyword(s):  
Excited State ◽  
Excited States ◽  
Ground State ◽  
Transient Absorption ◽  
Electronic Energy ◽  
Transient Absorption Spectroscopy ◽  
Electronic Relaxation ◽  
Vibrationally Excited ◽  
Excited State Dynamics ◽  
Π State

<p></p><p> Damage to RNA from ultraviolet radiation induce chemical modifications to the nucleobases. Unraveling the excited states involved in these reactions is essential, but investigations aimed at understanding the electronic-energy relaxation pathways of the RNA nucleotide uridine 5’-monophosphate (UMP) have not received enough attention. In this Letter, the excited-state dynamics of UMP is investigated in aqueous solution. Excitation at 267 nm results in a trifurcation event that leads to the simultaneous population of the vibrationally-excited ground state, a longlived <sup>1</sup>n<sub>O</sub>π* state, and a receiver triplet state within 200 fs. The receiver state internally convert to the long-lived <sup>3</sup>ππ* state in an ultrafast time scale. The results elucidate the electronic relaxation pathways and clarify earlier transient absorption experiments performed for uracil derivatives in solution. This mechanistic information is important because long-lived nπ* and ππ* excited states of both singlet and triplet multiplicities are thought to lead to the formation of harmful photoproducts.</p><p></p>

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.

Photodissociation Structural Dynamics of TrirutheniumDodecacarbonyl Investigated by X-ray Transient Absorption Spectroscopy

2013 ◽  
Vol 117 (39) ◽  
pp. 9807-9813 ◽  
Author(s):  
Michael R. Harpham ◽  
Andrew, B. Stickrath ◽  
Xiaoyi, Zhang ◽  
Jier Huang ◽  
Michael W. Mara ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Structural Dynamics ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
X Ray

scholarly journals Tunable Non-linear Refraction Properties and Ultrafast Excited State Dynamics of Dicyanomethylene Dihydrofuran Derivative

2020 ◽  
Vol 8 ◽  
Author(s):  
Linpo Yang ◽  
Zhongguo Li ◽  
Taihui Wei ◽  
Liming Zhou ◽  
Feng Li ◽  
...  
Keyword(s):  
Excited State ◽  
Transient Absorption ◽  
Refraction Index ◽  
Fast Response ◽  
Transient Absorption Spectroscopy ◽  
Relaxation Dynamics ◽  
Substantial Impact ◽  
Femtosecond Transient Absorption ◽  
Non Linear ◽  
Linear Optical

The third order non-linear optical response of a dicyanomethylene dihydrofuran compound (DCDHF-2V) was investigated using a Z-scan technique in picosecond and nanosecond time regimes. The results show that DCDHF-2V has excellent excited state non-linear refraction properties on both time regimes, and the non-linear refraction index is also solvent-dependent in the nanosecond regime. The excited state relaxation dynamics of DCDHF-2V were demystified via femtosecond transient absorption spectroscopy. The TA spectra reveal that the solvent viscosities have a substantial impact on the excited state relaxation of DCDHF-2V. The exotic photophysical phenomena in DCDHF-2V reported herein can shed new light on future development of small organic non-linear optical materials with large non-linear coefficients and fast response.

Electronic relaxation pathways of the biologically relevant pterin chromophore

2017 ◽  
Vol 19 (20) ◽  
pp. 12720-12729 ◽  
Author(s):  
R. M. DiScipio ◽  
R. Y. Santiago ◽  
D. Taylor ◽  
C. E. Crespo-Hernández
Keyword(s):  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
Relaxation Mechanism ◽  
Transient Absorption Spectroscopy ◽  
Electronic Relaxation ◽  
Biologically Relevant ◽  
Ultrafast Relaxation ◽  
First Time

Femtosecond-to-microsecond transient absorption spectroscopy is used to report the ultrafast relaxation mechanism of 2-amino-1H-pteridin-4-one (pterin) for the first time.

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