Dynamics of the Singlet Excited States of Diarylethenes in the Presence of Charge-Transfer Interactions. A Picosecond Laser Flash Photolysis Study

1997 ◽  
Vol 101 (51) ◽  
pp. 9870-9876
Author(s):  
L. Latterini ◽  
F. Elisei ◽  
G. G. Aloisi ◽  
M. A. J. Rodgers
Keyword(s):  
Charge Transfer ◽  
Excited States ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Picosecond Laser ◽  
Laser Flash

Reduction of hexaammineruthenium(III) ions by a series of tris(polypyridyl)chromium(II) ions – Revisiting the Cr(NN)33+/2+ self-exchange rate

2001 ◽  
Vol 79 (7) ◽  
pp. 1124-1127 ◽  
Author(s):  
K Omar Zahir
Keyword(s):  
Exchange Rate ◽  
Excited States ◽  
Rate Constants ◽  
Driving Force ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Outer Sphere ◽  
Laser Flash ◽  
Exchange Rate Constant ◽  
Kinetics Of

The kinetics of the outer-sphere oxidation of Cr(NN)32+ ions (NN = 2,2'-bipyridine, 1,10-phenanthroline, and their substituted analogs) by hexaammineruthenium(III) was studied using laser flash photolysis. The Cr(NN)32+ ions were generated via the reductive quenching of the *Cr(NN)33+ excited states by oxalate ions or by H2edta2–. The second-order rate constants were found to vary with the driving force of the reaction. The rate constants increase from (7.1 ± 0.5) × 106 M–1 s–1 for Cr(5-Clphen)32+ to (2.6 ± 0.2) × 108 M–1 s–1 for Cr(4,7-Me2phen)32+. The self-exchange rate constant for the couple (Cr(NN)33+/2+) was calculated by applying Marcus cross relation to present and other known reactions of Cr(NN)3n+ ions, where n = 3 or 2 with various reactants and is estimated to be (6 ± 4) × 107 M–1 s–1.Key words: tris(polypyridyl)chromium(II)/(III) self-exchange rate, hexaammineruthenium(III), oxidation of Cr(NN)32+.

Primary photochemical events in CdS semiconductor colloids as probed by picosecond laser flash photolysis

1989 ◽  
Vol 157 (5) ◽  
pp. 384-389 ◽  
Author(s):  
Prashant V. Kamat ◽  
Thomas W. Ebbesen ◽  
Nada M. Dimitrijević ◽  
A.J. Nozik
Keyword(s):  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Picosecond Laser ◽  
Laser Flash

A laser flash photolysis study of the behaviour of polyfluorophenyl ketones in solution

1989 ◽  
Vol 67 (5) ◽  
pp. 927-932 ◽  
Author(s):  
D. R. Boate ◽  
L. J. Johnston ◽  
J. C. Scaiano
Keyword(s):  
Charge Transfer ◽  
Hydrogen Transfer ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Oxidation Potential ◽  
Triplet States ◽  
Excellent Correlation ◽  
Triplet Energy ◽  
Keywords Laser

Decafluorobenzophenone triplets, which have a triplet energy very close to that of benzophenone, are much more reactive than benzophenone in quenching reactions that involve hydrogen transfer and/or charge transfer. An excellent correlation has been observed between the rate constants for charge transfer quenching and the oxidation potential of the substrate. In the case of 2-propanol, where the reactivity can be fully accounted for by hydrogen transfer, decafluorobenzophenone is 35 times more reactive than benzophenone. Pentafluorobenzophenone shows intermediate behaviour. Keywords: laser photolysis, benzophenones, triplet states, charge transfer, photoreduction.

Time-resolved nanosecond and picosecond absorption studies of excited-state properties of 1-thiobenzoylnaphthalene

1989 ◽  
Vol 67 (6) ◽  
pp. 967-972 ◽  
Author(s):  
R. Minto ◽  
A. Samanta ◽  
P.K. Das
Keyword(s):  
Rate Constants ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Picosecond Laser ◽  
Laser Flash ◽  
Quantum Yields ◽  
Pulse Excitation ◽  
Nanosecond Laser Pulse ◽  
Nanosecond Laser ◽  
Quenching Rate

1-Thiobenzoylnaphthalene (TBN), known for its pericyclization reaction from the lowest excited singlet state (S1), has been subjected to nanosecond and picosecond laser flash photolysis studies. The two major transients observed in the course of nanosecond laser pulse excitation are (i) the short-lived triplet characterized by two absorption maxima (400–410 and 740–750 nm) and submicrosecond intrinsic lifetimes (80–130 ns) and (ii) a relatively long-lived species (λmax = 520 nm and τ = 220–240 ns). Various triplet-related photophysical data of TBN, including self-quenching and bimolecular quenching rate constants, have been determined. The existence of a photochemical path from S1 manifests itself in low intersystem crossing quantum yields, particularly in the polar/hydrogen-bonding solvent, methanol. From the build-up of the triplet under picosecond excitation into S1 the lifetime of the latter is estimated to be ≤ 50 ps (in benzene). The fast intrinsic decay of TBN triplet is attributable to facile intra- and intermolecular photochemistry. The 520 nm transient species could not be definitively assigned, except that it is neither a triplet nor a triplet-derived product and that it arises via photochemistry from S1. Keywords: laser flash photolysis, triplet, transients, absorption maxima, lifetimes, quenching rate constants, photochemistry, 1-thiobenzoylnaphthalenes.

Laser flash photolysis of metal oxide supported vanadyl catalysts. Spectroscopic evidence for the ligand-to-metal charge-transfer state

2006 ◽  
Vol 16 (2) ◽  
pp. 216-220 ◽  
Author(s):  
Hermenegildo García ◽  
Jose Manuel López-Nieto ◽  
Emilio Palomares ◽  
Heinz D. Roth ◽  
Benjamín Solsona
Keyword(s):  
Charge Transfer ◽  
Metal Oxide ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Charge Transfer State ◽  
Metal Charge ◽  
Spectroscopic Evidence ◽  
Metal Charge Transfer ◽  
Transfer State

Photochemical transformation of an iron(iii)–arsenite complex in acidic aqueous solution

2016 ◽  
Vol 15 (3) ◽  
pp. 431-439 ◽  
Author(s):  
Ivan P. Pozdnyakov ◽  
Wei Ding ◽  
Jing Xu ◽  
Long Chen ◽  
Feng Wu ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Charge Transfer ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Photochemical Transformation ◽  
Acidic Aqueous Solution ◽  
Metal Charge ◽  
Metal Charge Transfer

An Fe(iii)–As(iii) complex was characterized by UV/Vis spectra and its laser flash photolysis via ligand-to-metal charge transfer resulted in the intermediate of Fe(ii)–As(iv).

scholarly journals Dynamics of small molecules within the F127 PEO-PPO-PEO triblock copolymer gel and sol phases studied at the molecular scale

2022 ◽  
Author(s):  
Suma S. Thomas ◽  
Helia Hosseini-Nejad ◽  
Cornelia Bohne
Keyword(s):  
Excited States ◽  
Rate Constants ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Supramolecular System ◽  
Quenching Rate ◽  
Naphthalene Derivatives ◽  
Decay Rate Constant ◽  
Triplet Excited States

The dynamics of naphthalene derivatives with different hydrophobicities bound to F127 polyethyleneoxide-polypropyleneoxide-polyethyleneoxide (PEO-PPO-PEO) micelles in the gel and sol phases were studied using a quenching methodology for the triplet excited states of the naphthalenes. Studies with triplet excited states probe a larger reaction volume than the volumes accessible when using fluorescent singlet excited states. The use of triplet excited states enables the determination of the dynamics between different compartments of a supramolecular system, which in the case of F127 micelles are the micellar core, the micellar corona and the aqueous phase. This report includes laser flash photolysis studies for the four naphthalene derivatives in the F127 gel and sol phases. The triplet excited states were quenched using the nitrite anion as the quenchers. The association and dissociation rate constants of the naphthalenes from the micelles and the quenching rate constants for the naphthalenes bound to the micelles were determines from the curved quenching plot (observed decay rate constant vs. nitrite concentration).

Nanosecond and picosecond laser flash photolysis studies of 2,2′-dinitrodiphenylmethanes

1993 ◽  
Vol 70 (3) ◽  
pp. 245-251 ◽  
Author(s):  
T. Mathew ◽  
D. Ramaiah ◽  
C.P. Joshua ◽  
D. Weir ◽  
M.V. George
Keyword(s):  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Picosecond Laser ◽  
Laser Flash
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