scholarly journals Singlet and Triplet Exciton Dynamics of Violanthrone

2021 ◽  
Author(s):  
Elham Gholizadeh ◽  
Shyamal Prasad ◽  
Lara Gillan ◽  
Dane R. McCamey ◽  
Murad J. Y. Tayebjee ◽  
...  
Keyword(s):  
Triplet State ◽  
Ground State ◽  
Density Functional ◽  
Transient Absorption ◽  
Density Functional Theory Calculations ◽  
Emission Feature ◽  
Stimulated Emission ◽  
Transient Absorption Spectrum ◽  
Exciton Dynamics ◽  
Solid Film

<div>The exciton dynamics of violanthrone-79 are investigated in solution and in the solid</div><div>state. In solution, the photo-prepared singlet is found to exhibit a strong ground-state bleach</div><div>and stimulated emission feature, but when sensitized in its triplet state, exhibits only a narrow</div><div>and weak ground-state bleach. As supported by density functional theory calculations,</div><div>this is explained by the triplet state having absorptions in the same region, with a similar</div><div>oscillator strength, as the ground state molecule. In solid films, the excited singlet is</div><div>found to survive only 100 ps, giving way to a long-lived transient absorption spectrum with</div><div>characteristics reminiscent of the triplet in solution. This is interpreted in terms of singlet</div><div>fission in the solid film.</div>

scholarly journals Singlet and Triplet Exciton Dynamics of Violanthrone

2021 ◽  
Author(s):  
Elham Gholizadeh ◽  
Shyamal Prasad ◽  
Lara Gillan ◽  
Dane R. McCamey ◽  
Murad J. Y. Tayebjee ◽  
...  
Keyword(s):  
Triplet State ◽  
Ground State ◽  
Density Functional ◽  
Transient Absorption ◽  
Density Functional Theory Calculations ◽  
Emission Feature ◽  
Stimulated Emission ◽  
Transient Absorption Spectrum ◽  
Exciton Dynamics ◽  
Solid Film

<div>The exciton dynamics of violanthrone-79 are investigated in solution and in the solid</div><div>state. In solution, the photo-prepared singlet is found to exhibit a strong ground-state bleach</div><div>and stimulated emission feature, but when sensitized in its triplet state, exhibits only a narrow</div><div>and weak ground-state bleach. As supported by density functional theory calculations,</div><div>this is explained by the triplet state having absorptions in the same region, with a similar</div><div>oscillator strength, as the ground state molecule. In solid films, the excited singlet is</div><div>found to survive only 100 ps, giving way to a long-lived transient absorption spectrum with</div><div>characteristics reminiscent of the triplet in solution. This is interpreted in terms of singlet</div><div>fission in the solid film.</div>

scholarly journals Ultrafast proton release reaction and primary photochemistry of phycocyanobilin in solution observed with fs-time-resolved mid-IR and UV/Vis spectroscopy

2021 ◽  
Author(s):  
Maximilian Theiß ◽  
Merten Grupe ◽  
Tilman Lamparter ◽  
Maria Andrea Mroginski ◽  
Rolf Diller
Keyword(s):  
Density Functional ◽  
Transient Absorption ◽  
Vibrational Analysis ◽  
Density Functional Theory Calculations ◽  
Chem Phys ◽  
Molecular Structures ◽  
Ir Absorption ◽  
Time Resolved ◽  
Time Constants ◽  
Vis Spectroscopy

AbstractDeactivation processes of photoexcited (λex = 580 nm) phycocyanobilin (PCB) in methanol were investigated by means of UV/Vis and mid-IR femtosecond (fs) transient absorption (TA) as well as static fluorescence spectroscopy, supported by density-functional-theory calculations of three relevant ground state conformers, PCBA, PCBB and PCBC, their relative electronic state energies and normal mode vibrational analysis. UV/Vis fs-TA reveals time constants of 2.0, 18 and 67 ps, describing decay of PCBB*, of PCBA* and thermal re-equilibration of PCBA, PCBB and PCBC, respectively, in line with the model by Dietzek et al. (Chem Phys Lett 515:163, 2011) and predecessors. Significant substantiation and extension of this model is achieved first via mid-IR fs-TA, i.e. identification of molecular structures and their dynamics, with time constants of 2.6, 21 and 40 ps, respectively. Second, transient IR continuum absorption (CA) is observed in the region above 1755 cm−1 (CA1) and between 1550 and 1450 cm−1 (CA2), indicative for the IR absorption of highly polarizable protons in hydrogen bonding networks (X–H…Y). This allows to characterize chromophore protonation/deprotonation processes, associated with the electronic and structural dynamics, on a molecular level. The PCB photocycle is suggested to be closed via a long living (> 1 ns), PCBC-like (i.e. deprotonated), fluorescent species.

scholarly journals Investigation of different photochemical reactions of avobenzone derivatives by ultrafast transient absorption spectroscopy

2019 ◽  
Vol 18 (12) ◽  
pp. 3000-3007
Author(s):  
Jialin Wang ◽  
Yibo Lei ◽  
Yan Guo ◽  
Junxiao Wang ◽  
Jiani Ma
Keyword(s):  
Absorption Spectroscopy ◽  
Photochemical Reaction ◽  
Density Functional ◽  
Transient Absorption ◽  
Density Functional Theory Calculations ◽  
Photochemical Reactions ◽  
Transient Absorption Spectroscopy ◽  
Functional Theory ◽  
Ultrafast Transient Absorption ◽  
Ultrafast Transient Absorption Spectroscopy

Ultrafast transient absorption spectroscopy and density functional theory calculations are utilized to get a better understanding of photophysical and photochemical reaction mechanisms of AB-Me, AB-Pr, AB-Br and AB-Cl.

Density Functional Theory on NV Center in 4H SiC

2017 ◽  
Vol 897 ◽  
pp. 269-274 ◽  
Author(s):  
András Csóré ◽  
Ádám Gali
Keyword(s):  
Density Functional Theory ◽  
Ground State ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Vacancy Defect ◽  
The Other ◽  
Nitrogen Vacancy ◽  
Functional Theory ◽  
Triplet Ground State ◽  
Nv Center

Paramagnetic defects in solids have become attractive systems for quantum computing as well as magnetometry in recent years. One of the leading contenders is the negatively charged nitrogen-vacancy defect (NV center) in diamond proposed to be highly promising with respect the afore-mentioned applications. In our study we investigate the NCVSi defect in 3C, 4H and 6H SiC as alternative choices with superior properties. Electronic structure of NV center in SiC exhibits S = 1 triplet ground state with the possibility of optical spin polarization. On the other hand, our results obtained by density functional theory calculations may contribute to unambiguously identify the possible defect configurations.

scholarly journals Strategies for Computer-Aided Discovery of Novel Open-Shell Polymers

2021 ◽  
Author(s):  
Omri Abarbanel ◽  
Julisa Rozon ◽  
Geoffrey Hutchison
Keyword(s):  
Ground State ◽  
Conjugated Polymer ◽  
Density Functional ◽  
Singlet State ◽  
Density Functional Theory Calculations ◽  
Open Shell ◽  
Singlet Ground State ◽  
Functional Theory ◽  
Triplet Ground State ◽  
Homo Lumo

Organic π-conjugated polymers with a triplet ground state have been the focus of recent research for their interesting and unique electronic properties, arising from the presence of the two unpaired electrons. These polymers are usually built from alternating electron-donating and electron-accepting monomer pairs which lower the HOMO-LUMO gap and yield a triplet state instead of the typical singlet ground state. In this paper we use density functional theory calculations to explore the design rules that govern the creation of a ground state triplet conjugated polymer, and find that a small HOMO-LUMO gap in the singlet state is the best predictor for the existence of a triplet ground state, compared to previous use of pro-quinoidal character. This work can accelerate the discovery of new stable triplet materials by reducing the computa- tional resources needed for electronic-state calculations and the number of potential candidates for synthesis.

STRUCTURAL AND ELECTRONIC PROPERTIES OF DIPROPYL SULFIDE: A THEORETICAL INVESTIGATION

2006 ◽  
Vol 17 (08) ◽  
pp. 1179-1190 ◽  
Author(s):  
EMİNE DENİZ ÇALIŞIR ◽  
ŞAKİR ERKOÇ
Keyword(s):  
Density Functional Theory ◽  
Electronic Properties ◽  
Gas Phase ◽  
Ground State ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Vibrational Modes ◽  
Functional Theory ◽  
Structural And Electronic Properties ◽  
Semi Empirical

The structural, vibrational, electronic and QSAR properties of the dipropyl sulfide (DPS) molecule in gas phase have been investigated theoretically by performing semi-empirical molecular orbital (AM1 and PM3), ab initio (RHF) and density functional theory calculations. The geometry of the molecule has been optimized, infrared spectrum (vibrational modes and intensities) and the electronic properties of the molecule have been calculated in its ground state. It has been found that DPS molecule kinetically may not be stable however it is thermodynamically stable.

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