S1−S0Internal Conversion in Ketene. 1. The Role of Conical Intersections

1999 ◽  
Vol 103 (33) ◽  
pp. 6658-6668 ◽  
Author(s):  
David R. Yarkony
Keyword(s):  
Conical Intersections

scholarly journals Role of Conical Intersections on the Efficiency of Fluorescent Organic Molecular Crystals

2021 ◽  
Vol 125 (4) ◽  
pp. 1012-1024
Author(s):  
Miguel Rivera ◽  
Ljiljana Stojanović ◽  
Rachel Crespo-Otero
Keyword(s):  
Molecular Crystals ◽  
Conical Intersections ◽  
Organic Molecular Crystals

The states that hide in the shadows: the potential role of conical intersections in the ground state unimolecular decay of a Criegee Intermediate

2021 ◽  
Author(s):  
Barbara Marchetti ◽  
Vincent John Esposito ◽  
Rachel Bush ◽  
Tolga Karsili
Keyword(s):  
Ground State ◽  
Potential Role ◽  
Conical Intersections ◽  
Criegee Intermediates

Criegee intermediates (CIs) are of great significance to Earth’s troposphere – implicated in altering the tropospheric oxidation cycle and in forming low volatility products that typically condense to form secondary...

The role of pyrimidine nucleobase excimers in DNA photophysics and photoreactivity

2009 ◽  
Vol 81 (9) ◽  
pp. 1695-1705 ◽  
Author(s):  
Israel González-Ramírez ◽  
Teresa Climent ◽  
Juan José Serrano-Pérez ◽  
Remedios González-Luque ◽  
Manuela Merchán ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Quantum Chemical ◽  
Electronic States ◽  
Conical Intersections ◽  
Chemical Studies ◽  
Quantum Chemical Studies ◽  
Dna Nucleobases ◽  
Surface Crossings

Quantum chemical studies using the accurate CASPT2//CASSCF procedure show that π-stacked interactions in biochromophores such as pyrimidine (Pyr) DNA/RNA nucleobases pairs yield excimer-like situations which behave as precursors of processes like charge transfer (CT) or photoreactivity and are the source of the emissive properties in DNA. Examples are the CT between adjacent DNA nucleobases in a strand of oligonucleotides and the photodimerization taking place in cytosine (C) pairs leading to cyclobutanecytosine (CBC) mutants. These processes take place through nonadiabatic photochemical mechanisms whose evolution is determined by the presence and accessibility of conical intersections (CIs) and other surface crossings between different electronic states.

Conical intersections in molecular photochemistry – the role of phase change

2000 ◽  
Vol 259 (2-3) ◽  
pp. 249-261 ◽  
Author(s):  
Shmuel Zilberg ◽  
Yehuda Haas
Keyword(s):  
Phase Change ◽  
Conical Intersections

scholarly journals The role of conical intersections on the efficiency of fluorescent organic molecular crystals

2020 ◽  
Author(s):  
Miguel Rivera ◽  
Ljiljana Stojanovic ◽  
Rachel Crespo Otero
Keyword(s):  
Solid State ◽  
Minimum Energy ◽  
Molecular Crystals ◽  
State Level ◽  
Conical Intersections ◽  
Decay Channels ◽  
Nonradiative Decay ◽  
Exciton Coupling ◽  
Organic Molecular Crystals

<p>Organic molecular crystals are attractive materials for luminescent applications due to their promised tunability. However, the link between chemical structure and emissive behaviour is poorly understood due to the numerous interconnected factors which are at play in determining radiative and non-radiative behaviours at the solid state level. In particular, the decay through conical intersection dominates the nonadiabatic regions of the potential energy surface, and thus their accessibility is a telling indicator of the luminosity of the material. In this study, we investigate the radiative mechanism for five organic molecular crystals which display solid state emission, with a focus on the role of conical intersections in their photomechanisms. The objective is to situate the importance of the accessibility of conical intersections with regards to emissive behaviour, taking into account other nonradiative decay channels, namely vibrational decay, and exciton hopping. We begin by giving a brief overview of the structural patterns of the five systems within a larger pool of thirteen crystals for a richer comparison. We observe that due to the prevalence of sheet-like and herringbone packing in organic molecular crystals, the conformational diversity of crystal dimers is limited. Additionally, similarly spaced dimers have exciton coupling values of similar order within a 50 meV interval. Next, we focus on three exemplary cases, where we disentangle the role of nonradiative decay mechanisms and show how rotational minimum energy conical intersections in vacuum lead to puckered ones in crystal, increasing their instability upon crystallisation in typical packing motifs. In contrast, molecules with puckered conical intersections in vacuum tend to conserve this trait upon crystallisation, and therefore their quantum yield of fluorescence is determined predominantly by other nonradiative decay mechanisms.<br></p>

scholarly journals The role of conical intersections on the efficiency of fluorescent organic molecular crystals

2020 ◽  
Author(s):  
Miguel Rivera ◽  
Ljiljana Stojanovic ◽  
Rachel Crespo Otero
Keyword(s):  
Solid State ◽  
Minimum Energy ◽  
Molecular Crystals ◽  
State Level ◽  
Conical Intersections ◽  
Decay Channels ◽  
Nonradiative Decay ◽  
Exciton Coupling ◽  
Organic Molecular Crystals

<p>Organic molecular crystals are attractive materials for luminescent applications due to their promised tunability. However, the link between chemical structure and emissive behaviour is poorly understood due to the numerous interconnected factors which are at play in determining radiative and non-radiative behaviours at the solid state level. In particular, the decay through conical intersection dominates the nonadiabatic regions of the potential energy surface, and thus their accessibility is a telling indicator of the luminosity of the material. In this study, we investigate the radiative mechanism for five organic molecular crystals which display solid state emission, with a focus on the role of conical intersections in their photomechanisms. The objective is to situate the importance of the accessibility of conical intersections with regards to emissive behaviour, taking into account other nonradiative decay channels, namely vibrational decay, and exciton hopping. We begin by giving a brief overview of the structural patterns of the five systems within a larger pool of thirteen crystals for a richer comparison. We observe that due to the prevalence of sheet-like and herringbone packing in organic molecular crystals, the conformational diversity of crystal dimers is limited. Additionally, similarly spaced dimers have exciton coupling values of similar order within a 50 meV interval. Next, we focus on three exemplary cases, where we disentangle the role of nonradiative decay mechanisms and show how rotational minimum energy conical intersections in vacuum lead to puckered ones in crystal, increasing their instability upon crystallisation in typical packing motifs. In contrast, molecules with puckered conical intersections in vacuum tend to conserve this trait upon crystallisation, and therefore their quantum yield of fluorescence is determined predominantly by other nonradiative decay mechanisms.<br></p>

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