Triplet state quenching of phenosafranine dye by indolic compounds studied by transient absorption spectroscopy

2015 ◽  
Vol 14 (2) ◽  
pp. 407-413 ◽  
Author(s):  
Martín F. Broglia ◽  
Carlos M. Previtali ◽  
Sonia G. Bertolotti
Keyword(s):  
Triplet State ◽  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Transient Absorption Spectroscopy ◽  
Synthetic Dye ◽  
Biological Relevance ◽  
Indolic Compounds

The interaction of the triplet state of the synthetic dye phenosafranine (3,7-diamino-5-phenylphenazinium chloride) with indolic compounds of biological relevance was investigated in water by means of laser flash photolysis.

Absorption spectroscopy of singlet CH2 near 11 200 cm–1

2001 ◽  
Vol 79 (2-3) ◽  
pp. 347-358 ◽  
Author(s):  
K Kobayashi ◽  
T J Sears
Keyword(s):  
Absorption Spectroscopy ◽  
Near Infrared ◽  
Transient Absorption ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Energy Levels ◽  
Zero Point ◽  
Laser Flash ◽  
Infrared Region ◽  
Transient Absorption Spectroscopy

New spectra of methylene, CH2, in the near infrared region of the singlet band system have been obtained. They were detected by laser transient absorption spectroscopy following excimer laser flash photolysis of ketene, CH2CO, at 308 nm. The new data provide information on the nature and energies of rotational levels in three vibronic states that lie between approximately 11 500 and 13 000 cm–1 above the zero point level of the lower, ã1A1, state. Taken together with previous measurements, a fairly complete picture of the vibronic energy levels of CH2 in this region can be built up. There is generally good agreement with the recent computational studies on the singlet states of CH2, but some evidence for discrepancies for levels with K = 3 and higher near the minimum of the [Formula: see text]1B1 potential surface. PACS No.: 33.20Ea

scholarly journals Photoinduced oxidation of sea salt halides by aromatic ketones: a source of halogenated radicals

2009 ◽  
Vol 9 (2) ◽  
pp. 7681-7706 ◽  
Author(s):  
A. Jammoul ◽  
S. Dumas ◽  
B. D'Anna ◽  
C. George
Keyword(s):  
Triplet State ◽  
Transient Absorption ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Chemical Oxidation ◽  
Absorption Feature ◽  
Halide Anion ◽  
Oceanic Surface ◽  
Diffusion Controlled

Abstract. The interactions between benzophenone triplet state and halide anion species (Cl−, Br− and I−) have been studied by laser flash photolysis (at 355 nm) in aqueous solutions at room temperature. The decay of the triplet state of benzophenone was followed at 525 nm. Triplet lifetime measurements provided rate constants, kq (M−1 s−1), close to diffusion controlled limit for iodide (~8×109 M−1 s−1), somewhat less for bromide (~3×108 M−1 s−1) and much lower for chloride (>106 M−1 s−1). The halide (X−) quenches the triplet state, and a product, having a transient absorption at 355 nm and a lifetime much longer than that of the benzophenone triplet state, is formed. This transient absorption feature matches those of the corresponding radical anion (X2−). We therefore suggest that such reactive quenching can be a photosensitized source of halogen in the atmosphere and represents a driving force for the chemical oxidation of the oceanic surface.

scholarly journals Metal nanoparticle alters adenine induced charge transfer kinetics of vitamin K3 in magnetic field

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Ranjan Kumar Behera ◽  
Abhishek Sau ◽  
Leepsa Mishra ◽  
Sankalan Mondal ◽  
Kallol Bera ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Transient Absorption ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Hydrogen Atom Transfer ◽  
Metal Nanoparticle ◽  
Transient Absorption Spectroscopy ◽  
Vitamin K3 ◽  
Time Resolved

Abstract In this article, we highlight the alterations in the photoinduced electron transfer (ET) and hydrogen atom transfer (HAT) pathways between an anti-tumor drug vitamin-K3 (MQ) and a nucleobase adenine (ADN) in the presence of gold (Au) and iron (Fe) nanoparticles (NPs). Inside the confined micellar media, with laser flash photolysis corroborated with an external magnetic field (MF), we have detected the transient geminate radicals of MQ and ADN, photo-generated through ET and HAT. We observe that the presence of AuNP on the MQ-ADN complex (AuMQ-ADN) assists HAT by limiting the ET channel, on the other hand, FeNP on the MQ-ADN complex (FeMQ-ADN) mostly favors a facile PET. We hypothesize that through selective interactions of the ADN molecules with AuNP and MQ molecules with FeNP, a preferential HAT and PET process is eased. The enhanced HAT and PET have been confirmed by the escape yields of radical intermediates by time-resolved transient absorption spectroscopy in the presence of MF.

Article

1999 ◽  
Vol 77 (5-6) ◽  
pp. 787-791
Author(s):  
Lorenzo Brancaleon ◽  
Darryl Brousmiche ◽  
Linda J Johnston
Keyword(s):  
Electron Transfer ◽  
Photoinduced Electron Transfer ◽  
Transient Absorption ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Energy ◽  
Laser Flash ◽  
Transient Absorption Spectroscopy ◽  
Direct Excitation ◽  
Oxidation Potentials

The electron transfer photochemistry of 2,3-dicyanonaphthalene has been studied by a combination of fluorescence and transient absorption spectroscopy. The singlet excited state has a lifetime of 26 ns in acetonitrile and reacts with aromatic and alkene donors with oxidation potentials less than ~1.8 V with rate constants that are close to the diffusion-controlled limit. Transient absorption measurements demonstrate that the fluorescence quenching leads to efficient formation of free-radical ions. The radical ion yields have been measured for several donors and are compared to those for the more commonly used sensitizer, 1.4-dicyanonaphthalene. In the absence of added donors, direct excitation of 2,3-dicyanonaphthalene provides evidence for photoionization at high laser energy, in addition to triplet formation. The results illustrate the utility of this sensitizer for photoinduced electron transfer reactions.Key words: photoinduced electron transfer, laser flash photolysis, fluorescence, photosensitizers.

Effect of Aggregation on Bacteriochlorin a Triplet-state Formation: A Laser Flash Photolysis Study¶

2002 ◽  
Vol 76 (5) ◽  
pp. 480 ◽  
Author(s):  
Xavier Damoiseau ◽  
Francis Tfibel ◽  
Maryse Hoebeke ◽  
Marie-Pierre Fontaine-Aupart
Keyword(s):  
Triplet State ◽  
State Formation ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash

A reinvestigation of the interaction between triplet states of cyclohexenones and amines

1988 ◽  
Vol 66 (10) ◽  
pp. 2595-2600 ◽  
Author(s):  
D. Weir ◽  
J. C. Scaiano ◽  
D. I. Schuster
Keyword(s):  
Triplet State ◽  
Rate Constant ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Radical Cations ◽  
Laser Flash ◽  
Triplet States ◽  
New Evidence

Laser flash photolysis studies lead to the conclusion that the short-lived triplet states of cyclohexenones are readily quenched by amines. For example, in the case of 2-cyclohexen-1-one (1) its triplet state (τT = 40 ns in acetonitrile) is quenched by triethylamine with a rate constant of (9.0 ± 0.8) × 107 M−1 s−1. Cyclohexenone triplets are also quenched efficiently by DABCO and by triphenylamine leading to the formation of the corresponding amine radical cations. The new evidence reported rules out the involvement of long-lived detectable exciplexes.

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