Dye laser flash photolysis kinetics study of the reaction of ground-state atomic oxygen with hydrogen peroxide

1974 ◽  
Vol 78 (4) ◽  
pp. 463-464 ◽  
Author(s):  
D. D. Davis ◽  
W. Wong ◽  
R. Schiff
Keyword(s):  
Hydrogen Peroxide ◽  
Ground State ◽  
Atomic Oxygen ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Dye Laser ◽  
Kinetics Study

Synthesis and Characterization of Novel Platinum Acetylide Oligomers

2003 ◽  
Vol 771 ◽  
Author(s):  
Thomas M. Cooper ◽  
Benjamin C. Hall ◽  
Daniel G. McLean ◽  
Joy E. Rogers ◽  
Aaron R. Burke ◽  
...  
Keyword(s):  
Absorption Spectra ◽  
Ground State ◽  
Near Infrared ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Structure Property ◽  
Ground State Absorption ◽  
Excitation Spectra ◽  
C Nmr

AbstractAs part of an effort to develop a spectroscopic structure-property relationship in platinum acetylide oligomers, we have prepared a series of bidentate Pt(PBu3)2L2 compounds. The ligand was the series o-syd-C6H4-CΞC-(C6H4-CΞC)n-H, n = 0,1,2. The terminal oligomer unit consisted of a sydnone group ortho to the acetylene carbon. The compounds were characterized by various methods, including 13C-NMR, ground state absorption, fluorescence, phosphorescence and laser flash photolysis. The acetylenic 13C-NMR resonances showed sydnone influences that decreased with increasing number of monomer units. The ground state absorption spectra were slightly red shifted from those of the baseline oligomers not having a sydnone group. The low temperature emission and excitation spectra showed complex dependence on excitation and emission wavelengths, suggesting the chromphores resided in a distribution of solvent environments and conformations. Finally, broad triplet state absorption spectra were observed, with absorption throughout the visible and near infrared regions.

scholarly journals Time-Resolved Study of Light-Induced Ground State Proton Transfer from Acid Medium to 4-Nitrophenolate

2020 ◽  
Author(s):  
Leandro Scorsin ◽  
Leticia Martins ◽  
Haidi Fiedler ◽  
Faruk Nome ◽  
RENE NOME
Keyword(s):  
Acetic Acid ◽  
Proton Transfer ◽  
Electronic State ◽  
Ground State ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Proton Transfer Reaction ◽  
Ground Electronic State ◽  
Experimental Conditions

In the present work, we study the transient laser-induced formation of 4-nitrophenolate (4-NPO<sup>-</sup>) in the ground electronic state and subsequent proton transfer reaction with acetic acid and water with numerical calculations and laser flash photolysis. We employ the Debye-Smoluchowski spherically-symmetric diffusion model of photoacid proton transfer to determine experimental conditions for studying thermally activated chemical reactions in the ground electronic state. Numerically calculated protonation and deprotonation probabilities for 4-NPO<sup>-</sup> and 4-nitrophenol (4-NPOH) in both ground and excited states showed the feasibility of efficiently producing the ground state anion in the photoacid cycle. We performed laser flash photolysis measurements of 4-NPOH to characterize the photo-initiated ground state protonation and deprotonation rate constants of 4-NPO<sup>-</sup>/4-NPOH as a function of acetic acid, pH, temperature and viscosity. Overall, the work presented here shows a simple way to study fast competing bimolecular proton transfer reactions in non-equilibrium conditions in the ground electronic state <i>(GSPT)</i>.

scholarly journals Time-Resolved Study of Light-Induced Ground State Proton Transfer from Acid Medium to 4-Nitrophenolate

2020 ◽  
Author(s):  
Leandro Scorsin ◽  
Leticia Martins ◽  
Haidi Fiedler ◽  
Faruk Nome ◽  
RENE NOME
Keyword(s):  
Acetic Acid ◽  
Proton Transfer ◽  
Electronic State ◽  
Ground State ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Proton Transfer Reaction ◽  
Ground Electronic State ◽  
Experimental Conditions

In the present work, we study the transient laser-induced formation of 4-nitrophenolate (4-NPO<sup>-</sup>) in the ground electronic state and subsequent proton transfer reaction with acetic acid and water with numerical calculations and laser flash photolysis. We employ the Debye-Smoluchowski spherically-symmetric diffusion model of photoacid proton transfer to determine experimental conditions for studying thermally activated chemical reactions in the ground electronic state. Numerically calculated protonation and deprotonation probabilities for 4-NPO<sup>-</sup> and 4-nitrophenol (4-NPOH) in both ground and excited states showed the feasibility of efficiently producing the ground state anion in the photoacid cycle. We performed laser flash photolysis measurements of 4-NPOH to characterize the photo-initiated ground state protonation and deprotonation rate constants of 4-NPO<sup>-</sup>/4-NPOH as a function of acetic acid, pH, temperature and viscosity. Overall, the work presented here shows a simple way to study fast competing bimolecular proton transfer reactions in non-equilibrium conditions in the ground electronic state <i>(GSPT)</i>.

A laser flash photolysis kinetics study of the reaction OH+H2O2→HO2+H2O

1981 ◽  
Vol 75 (9) ◽  
pp. 4390-4395 ◽  
Author(s):  
P. H. Wine ◽  
D. H. Semmes ◽  
A. R. Ravishankara
Keyword(s):  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Kinetics Study

Scavenging of photogenerated singlet molecular oxygen and superoxide radical anion by sulpha drugs - Kinetics and mechanism

2004 ◽  
Vol 82 (12) ◽  
pp. 1752-1759 ◽  
Author(s):  
Marta Díaz ◽  
Marta Luiz ◽  
Sonia Bertolotti ◽  
Sandra Miskoski ◽  
Norman A García
Keyword(s):  
Visible Light ◽  
Ground State ◽  
Radical Anion ◽  
Superoxide Radical ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Singlet Molecular Oxygen ◽  
Superoxide Radical Anion ◽  
Sulpha Drugs

The ability of the sulfanilic antibiotics (SDs), dapsone (DAP), sulfisoxazole (SFX), sulfadiazine (SFD), and sulfanilic acid (SFNA) to act as scavengers of the visible-light-photogenerated species superoxide radical anion (O2·–) and singlet molecular oxygen (O2(1Δg)) was studied employing the natural pigment riboflavin (Rf) and the artificial dye Rose Bengal as photosensitisers. A complex mechanism, common to all the SDs studied, was elucidated through stationary photolysis, polarographic detection of oxygen uptake, fluorescence spectroscopy, time-resolved phosphorescence detection of O2(1Δg), and laser flash photolysis. Visible-light irradiation of aqueous and aqueous methanolic solutions of Rf (ca. 0.02 mmol/L) plus SD (ca. 0.5 mmol/L) photogenerated excited singlet and triplet Rf (1Rf* and 3Rf*). Under these experimental conditions, only 3Rf* is quenched either by oxygen, giving rise to O2(1Δg) by electronic energy transfer to dissolved ground-state oxygen, or by SD, yielding semireduced Rf through an electron-transfer process. Complementary experiments performed in pure water employing superoxide dismutase and sodium azide inhibition of oxygen uptake, in parallel with laser flash photolysis data, showed that O2·– is also formed, probably due to the reaction of the anion radical from Rf with dissolved oxygen, yielding also neutral, ground-state Rf. Both active oxygen species, namely, O2·– and O2(1Δg), are quenched by the SDs and, as a result, photodegradation of the SDs — each to a different extent — and photodegradation of the sensitiser itself were observed. The SDs that kinetically behave as the better physical quenchers of O2(1Δg), which are in principle good candidates as photoprotectors, namely, DAP and SFD, suffer photooxidation, exhibiting high to moderate oxygen consumption rates due to the O2·– oxidative pathway, whereas for SFNA and SFX, oxidation predominantly occurs through an O2(1Δg)-mediated mechanism. Microbiological results for SFX, taken as a representative SD, indicate that the photodegradation of the drug, upon visible-light Rf-sensitised irradiation, is accompanied by a net loss in bacteriostatic activity.Key words: photooxidation, singlet oxygen, superoxide radical anion, sulpha drugs.

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