scholarly journals Ultrafast dynamics in polycyclic aromatic hydrocarbons: the key case of conical intersections at higher excited states and their role in the photophysics of phenanthrene monomer

2019 ◽  
Vol 21 (31) ◽  
pp. 16981-16988 ◽  
Author(s):  
M. Nazari ◽  
C. D. Bösch ◽  
A. Rondi ◽  
A. Francés-Monerris ◽  
M. Marazzi ◽  
...  
Keyword(s):  
Excited State ◽  
Excited States ◽  
Aromatic Hydrocarbons ◽  
Ultrafast Dynamics ◽  
Simultaneous Presence ◽  
Conical Intersections ◽  
Polycyclic Aromatic ◽  
Adiabatic Transitions ◽  
Proper Interpretation ◽  
Higher Excited States

Proper interpretation of phenanthrene's and similar PAHs’ photocycle relies on two higher excited state relaxations due to the simultaneous presence of non-adiabatic and adiabatic transitions.

scholarly journals Exploitation of Baird Aromaticity and Clar’s Rule for Tuning the Triplet Energies of Polycyclic Aromatic Hydrocarbons

Chemistry ◽  
2021 ◽  
Vol 3 (2) ◽  
pp. 532-549
Author(s):  
Felix Plasser
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Excited States ◽  
Aromatic Hydrocarbons ◽  
Density Functional ◽  
Materials Science ◽  
Chemical Shifts ◽  
Qualitative Description ◽  
Triplet States ◽  
Excitation Energies ◽  
Polycyclic Aromatic

Polycyclic aromatic hydrocarbons (PAH) are a prominent substance class with a variety of applications in molecular materials science. Their electronic properties crucially depend on the bond topology in ways that are often highly non-intuitive. Here, we study, using density functional theory, the triplet states of four biphenylene-derived PAHs finding dramatically different triplet excitation energies for closely related isomeric structures. These differences are rationalised using a qualitative description of Clar sextets and Baird quartets, quantified in terms of nucleus independent chemical shifts, and represented graphically through a recently developed method for visualising chemical shielding tensors (VIST). The results are further interpreted in terms of a 2D rigid rotor model of aromaticity and through an analysis of the natural transition orbitals involved in the triplet excited states showing good consistency between the different viewpoints. We believe that this work constitutes an important step in consolidating these varying viewpoints of electronically excited states.

scholarly journals Exploitation of Baird Aromaticity and Clar's Rule for Tuning the Triplet Energies of Polycyclic Aromatic Hydrocarbons

2021 ◽  
Author(s):  
Felix Plasser
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Excited States ◽  
Aromatic Hydrocarbons ◽  
Density Functional ◽  
Materials Science ◽  
Chemical Shifts ◽  
Qualitative Description ◽  
Triplet States ◽  
Excitation Energies ◽  
Polycyclic Aromatic

Polycyclic aromatic hydrocarbons (PAH) are a prominent substance class with a variety of applications in molecular materials science. Their electronic properties crucially depend on the bond topology in ways that are often highly non-intuitive. Here, we study, using density functional theory, the triplet states of four PAHs based on the biphenylene motif finding dramatically different triplet excitation energies for closely related isomeric structures. These differences are rationalised using a qualitative description of Clar sextets and Baird quartets, quantified in terms of nucleus independent chemical shifts, and represented graphically through a recently developed method for visualising chemical shielding tensors (VIST). These results are further interpreted in terms of a 2D rigid rotor model of aromaticity and through an analysis of the natural transition orbitals involved in the triplet excited states showing good consistency between the different viewpoints. We believe that this work constitutes an important step in consolidating these varying viewpoints of electronically excited states.

Disulfide bond photochemistry: the effects of higher excited states and different molecular geometries on disulfide bond cleavage

2019 ◽  
Vol 21 (8) ◽  
pp. 4176-4183 ◽  
Author(s):  
Jun Cao ◽  
Dong-Chu Chen
Keyword(s):  
Excited State ◽  
Excited States ◽  
Disulfide Bond ◽  
Bond Cleavage ◽  
Trajectory Simulations ◽  
Higher Excited States

We have investigated the light-induced cleavage of disulfide bond using MS-CASPT2 based trajectory simulations and provided insights into the intrinsic excited state properties of disulfide molecules.

Electronically excited states of PANH anions

2015 ◽  
Vol 17 (22) ◽  
pp. 14761-14772 ◽  
Author(s):  
Mallory L. Theis ◽  
Alessandra Candian ◽  
Alexander G. G. M. Tielens ◽  
Timothy J. Lee ◽  
Ryan C. Fortenberry
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Excited States ◽  
Aromatic Hydrocarbons ◽  
Electronically Excited States ◽  
Electronically Excited ◽  
Polycyclic Aromatic ◽  
Derivatives Of

The singly deprotonated anion derivatives of nitrogenated polycyclic aromatic hydrocarbons are shown likely to possess dipole-bound and even valence excited states for the larger systems.

scholarly journals Exploitation of Baird Aromaticity and Clar's Rule for Tuning the Triplet Energies of Polycyclic Aromatic Hydrocarbons

2021 ◽  
Author(s):  
Felix Plasser
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Excited States ◽  
Aromatic Hydrocarbons ◽  
Density Functional ◽  
Materials Science ◽  
Chemical Shifts ◽  
Qualitative Description ◽  
Triplet States ◽  
Excitation Energies ◽  
Polycyclic Aromatic

Polycyclic aromatic hydrocarbons (PAH) are a prominent substance class with a variety of applications in molecular materials science. Their electronic properties crucially depend on the bond topology in ways that are often highly non-intuitive. Here, we study, using density functional theory, the triplet states of four PAHs based on the biphenylene motif finding dramatically different triplet excitation energies for closely related isomeric structures. These differences are rationalised using a qualitative description of Clar sextets and Baird quartets, quantified in terms of nucleus independent chemical shifts, and represented graphically through a recently developed method for visualising chemical shielding tensors (VIST). These results are further interpreted in terms of a 2D rigid rotor model of aromaticity and through an analysis of the natural transition orbitals involved in the triplet excited states showing good consistency between the different viewpoints. We believe that this work constitutes an important step in consolidating these varying viewpoints of electronically excited states.

scholarly journals Conical intersection dynamics of pyrimidine nucleosides tracked with sub-20-fs UV pulses

2019 ◽  
Vol 205 ◽  
pp. 10007
Author(s):  
Rocío Borrego-Varillas ◽  
Artur Nenov ◽  
Lucia Ganzer ◽  
Aurelio Oriana ◽  
Irene Conti ◽  
...  
Keyword(s):  
Excited State ◽  
Numerical Simulations ◽  
Ab Initio ◽  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Conical Intersection ◽  
Ultrafast Dynamics ◽  
Conical Intersections ◽  
Pyrimidine Nucleosides

By combining transient absorption spectroscopy with sub-20-fs UV pulses and ab initio numerical simulations we follow the ultrafast dynamics in pyrimidine nucleosides and visualize the passage through conical intersections presiding excited state deactivation.

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