scholarly journals Investigation of the Photophysical Properties of a Eu3+ Coordination Polymer Bearing an α-Nitrile Substituted β-Diketonate Ligand via Emission and Ultrafast Transient Absorption Spectroscopy

2015 ◽  
Vol 68 (9) ◽  
pp. 1392 ◽  
Author(s):  
Brodie L. Reid ◽  
Evan G. Moore ◽  
Brian W. Skelton ◽  
Mark I. Ogden ◽  
Massimiliano Massi
Keyword(s):  
Coordination Polymer ◽  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
Photophysical Properties ◽  
Transient Absorption Spectroscopy ◽  
Quantum Yields ◽  
Metal Centre ◽  
Antenna Effect ◽  
One Dimensional ◽  
Polymer Bearing

Reaction of the β-diketone ligand, 2-cyano-1,3-phenyl-1,3-propandione (LH), with hydrated EuCl3 in the presence of 1,10-phenanthroline (Phen), results in the crystallisation of a one-dimensional Eu3+ coordination polymer of formulation [Eu(Phen)(L)3]∞, formed by coordination of the nitrile group of an O,O′-bound ligand to a neighbouring metal centre. An investigation of the metal-centred emission of the polymer, both in the solid state and solution, revealed red emission characterised by relatively long-lived excited state lifetimes and high intrinsic quantum yields. However, analysis of the overall quantum yield and sensitisation efficiency reveals that ultrafast processes in the ligand potentially inhibit Eu3+ sensitisation. Further investigations into these processes using transient absorption spectroscopy suggest that substitution at the α-C position may significantly decrease sensitisation via the antenna effect.

scholarly journals Multiphoton Ionization of Nitrobenzene in Non-Aqueous Solutions: Characterization of the Cation and Ion-Molecule Chemistry

1991 ◽  
Vol 11 (2) ◽  
pp. 83-93 ◽  
Author(s):  
G. Siuzdak ◽  
J. J. Belbruno
Keyword(s):  
Aqueous Solutions ◽  
Absorption Spectroscopy ◽  
Ion Mobility ◽  
Transient Absorption ◽  
Multiphoton Ionization ◽  
Transient Absorption Spectroscopy ◽  
Quantum Yields ◽  
Nanosecond Pulses ◽  
Solvent Molecules

The phenoxy cation has been generated in polar and nonpolar solutions by multiphoton ionization of nitrobenzene using nanosecond pulses of 266 nm and 355 nm light. The ions have been characterized by pulsed conductivity (ion mobility) measurements and transient absorption spectroscopy. The involvement of the phenoxy ion in ion-molecule chemistry with either neutral solute or solvent molecules has also been observed and the photochemical products and quantum yields of the ion-molecule products are presented and compared with the neutral photochemistry results.

Attosecond transient-absorption spectroscopy in one-dimensional periodic crystals

2019 ◽  
Vol 100 (4) ◽  
Author(s):  
Meiwen Du ◽  
Candong Liu ◽  
Yinghui Zheng ◽  
Zhinan Zeng ◽  
Ruxin Li
Keyword(s):  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
One Dimensional

State Dependent Photochemical and Photophysical Behavior of Dithiolate Ester and Trithiocarbonate RAFT Polymerization Agents.

2020 ◽  
Author(s):  
Daniel Falvey ◽  
Matthew Thum ◽  
Steven Wolf
Keyword(s):  
Electron Transfer ◽  
Transient Absorption ◽  
Raft Polymerization ◽  
Photophysical Properties ◽  
Energy Levels ◽  
Transient Absorption Spectroscopy ◽  
Quantum Yields ◽  
Peak Reduction ◽  
Initiation Mechanism ◽  
Reduction Potentials

The rise in popularity of photochemically initiated RAFT polymerization (photoRAFT) along with the broad spectrum of proposed, and possible, initiation mechanisms results in the need for careful characterization of the photophysical properties of some common RAFT agents. Direct irradiation of the RAFT agent as a means to generate radicals, also known as the photoiniferter mechanism, is one commonly proposed mechanism. The current study shows that the dithioesters and trithiocarbonates have lowest singlet, and triplet excited state energy levels that are close to, or lower then C-S bond dissociation energies. Excitation of these agents into their S<sub>1</sub> band results in negligible radical production, while excitation into S<sub>2</sub> or higher results in the decomposition of dithioesters and trithiocarbonates resulting in radical formation, but with low quantum yields. Likewise, there is significant literature precedence for an electron transfer initiation mechanism, PET-RAFT. It is shown that the dithioesters and trithiocarbonates all show peak reduction potentials at ca. -1.0 V (vs. SCE). However, transient absorption spectroscopy studies of the electron transfer from a mediator shows that theses reactions occur rapidly only when the mediator potential is more negative than -1.2 V (vs. SCE).

scholarly journals Individual control of singlet lifetime and triplet yield in halogen-substituted coumarin derivatives

RSC Advances ◽  
2020 ◽  
Vol 10 (45) ◽  
pp. 27096-27102
Author(s):  
Katrin E. Oberhofer ◽  
Mikayel Musheghyan ◽  
Sebastian Wegscheider ◽  
Martin Wörle ◽  
Eleonora D. Iglev ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
Photophysical Properties ◽  
Transient Absorption Spectroscopy ◽  
Coumarin Derivatives ◽  
Individual Control

The photophysical properties of three 3-diethylphosphonocoumarin derivatives are studied by transient absorption spectroscopy and DFT calculations.

State Dependent Photochemical and Photophysical Behavior of Dithiolate Ester and Trithiocarbonate RAFT Polymerization Agents.

2020 ◽  
Author(s):  
Daniel Falvey ◽  
Matthew Thum ◽  
Steven Wolf
Keyword(s):  
Electron Transfer ◽  
Transient Absorption ◽  
Raft Polymerization ◽  
Photophysical Properties ◽  
Energy Levels ◽  
Transient Absorption Spectroscopy ◽  
Quantum Yields ◽  
Peak Reduction ◽  
Initiation Mechanism ◽  
Reduction Potentials

The rise in popularity of photochemically initiated RAFT polymerization (photoRAFT) along with the broad spectrum of proposed, and possible, initiation mechanisms results in the need for careful characterization of the photophysical properties of some common RAFT agents. Direct irradiation of the RAFT agent as a means to generate radicals, also known as the photoiniferter mechanism, is one commonly proposed mechanism. The current study shows that the dithioesters and trithiocarbonates have lowest singlet, and triplet excited state energy levels that are close to, or lower then C-S bond dissociation energies. Excitation of these agents into their S<sub>1</sub> band results in negligible radical production, while excitation into S<sub>2</sub> or higher results in the decomposition of dithioesters and trithiocarbonates resulting in radical formation, but with low quantum yields. Likewise, there is significant literature precedence for an electron transfer initiation mechanism, PET-RAFT. It is shown that the dithioesters and trithiocarbonates all show peak reduction potentials at ca. -1.0 V (vs. SCE). However, transient absorption spectroscopy studies of the electron transfer from a mediator shows that theses reactions occur rapidly only when the mediator potential is more negative than -1.2 V (vs. SCE).

Triplet excited state of diiodoBOPHY derivatives: preparation, study of photophysical properties and application in triplet–triplet annihilation upconversion

2016 ◽  
Vol 4 (8) ◽  
pp. 1623-1632 ◽  
Author(s):  
Caishun Zhang ◽  
Jianzhang Zhao
Keyword(s):  
Excited State ◽  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
Photophysical Properties ◽  
Transient Absorption Spectroscopy ◽  
Triplet Excited State ◽  
Triplet Triplet Annihilation

A pyrrole-BF2-based chromophore (BOPHY) was used for the preparation of triplet photosensitizers and the photophysical properties were studied using transient absorption spectroscopy.

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