Photolysis of hydrogen peroxide, photocatalytic effects of Cu(II) and reaction kinetics

1986 ◽  
Vol 51 (5) ◽  
pp. 973-981 ◽  
Author(s):  
Stanislav Luňák ◽  
Petr Sedlák ◽  
Josef Vepřek-Šiška
Keyword(s):  
Hydrogen Peroxide ◽  
Thermal Decomposition ◽  
Quantum Yield ◽  
Reaction Kinetics ◽  
Copper Ions ◽  
Oxidation States ◽  
Radiation Temperature ◽  
Quantum Yields ◽  
High Quantum ◽  
Catalytically Active

The quantum yield of hydrogen peroxide photolysis has been measured as a function of the concentration of photocatalytically active Cu2+ ions, intensity of photolytic radiation, temperature, and hydrogen peroxide concentration. The results obtained are consistent with the concept that high quantum yields of hydrogen peroxide photolysis (Φ >> 1) are due to thermal decomposition of hydrogen peroxide catalyzed by photochemically generated copper ions in oxidation states which are catalytically active.

Quantum Yields for the Photodegradation of Pollutants in Dilute Aqueous Solution: Phenol, 4-Chlorophenol and N-Nitrosodimethylamine

1996 ◽  
Vol 1 (2) ◽  
Author(s):  
Te-Fu L. Ho ◽  
James R. Bolton ◽  
Ewa Lipczynska-Kochany
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Quantum Yield ◽  
High Performance ◽  
Flash Photolysis ◽  
Quantum Yields ◽  
Visible Absorption ◽  
Dilute Aqueous Solution ◽  
Uv Visible ◽  
Photolysis Of Phenol

AbstractA broadband method has been applied to determine the quantum yields for the photochemical removal of three common pollutants: phenol, 4-chlorophenol and N-nitrosodimethylamine (NDMA) in dilute aqueous solution. Flash photolysis (xenon flash lamps) was used to cause a significant amount of photolysis without photolyzing intermediates. The analysis of reactant depletion following a single flash was carried out by high- performance liquid chromatography (HPLC) or UV/visible absorption spectroscopy. The method for determining quantum-yields employed p-benzoquinone as an actinometer and was validated by determining the average (200-400 nm) quantum yield for the generation of hydroxyl radicals from the photolysis of hydrogen peroxide (0.90 ± 0.10) and the quantum yields for the photolysis of phenol (0.13 ± 0.02) and 4-chlorophenol (0.24 ± 0.04). The values determined agree very well with the literature ones obtained with monochromatic radiation. The quantum yield for the direct photolysis of NDMA was found to be 0.11 ± 0.03 at neutral pH and 0.27 ± 0.02 at pH 2-4. Under conditions where hydrogen peroxide is the principal absorber, the NDMA quantum yield is 0.32 ± 0.04, independent of pH in the range 2-8.

Tunable RGB luminescence of a single molecule with high quantum yields through a rational design

2016 ◽  
Vol 4 (7) ◽  
pp. 1527-1532 ◽  
Author(s):  
Wen Li ◽  
Yu-Mo Zhang ◽  
Ting Zhang ◽  
Weiran Zhang ◽  
Minjie Li ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Single Molecule ◽  
Rational Design ◽  
Quantum Yields ◽  
High Quantum Yield ◽  
Fluorescent Switch ◽  
High Quantum

An organic single-molecule RGB luminescence material with a high quantum yield was realized by introducing the ESIPT and TBET mechanisms and combining an AIEE luminophore with a fluorescent switch.

scholarly journals Generation of Ketene With High Quantum Yield by a KrF Laser

1985 ◽  
Vol 5 (5) ◽  
pp. 257-273 ◽  
Author(s):  
Zhang Yunwu ◽  
W. Fuss ◽  
K. L. Kompa ◽  
F. Rebentrost
Keyword(s):  
Thermal Decomposition ◽  
Single Step ◽  
Quantum Yields ◽  
Methyl Radicals ◽  
High Quantum ◽  
Photochemical Formation ◽  
A Chain ◽  
Technical Interest ◽  
Approximate Rate ◽  
Pulsed Laser Irradiation

Acetone was photolyzed around 770 K by pulsed laser irradiation at 248 nm. The methyl radicals, generated in the primary step, trigger a chain reaction, producing ketene (CH2CO) and methane. Long chains (high quantum yields) result from low radical concentrations. Using a collimated laser beam of low intensity, quantum yields up to 300 have been demonstrated. Approximate rate constants have been derived and used for extrapolation to higher temperatures and different densities. Compared to the thermal process, the photochemical formation of ketene is faster. Therefore its thermal decomposition can be avoided to some extent. But the improvement is probably too small to be of technical interest. We also found indications that the thermal decomposition of acetone above about 500 to 600 K yields three fragments in a single step.

scholarly journals Luminescent polypyridyl heteroleptic CrIII complexes with high quantum yields and long excited state lifetimes

2020 ◽  
Vol 49 (39) ◽  
pp. 13528-13532
Author(s):  
Juan-Ramón Jiménez ◽  
Maxime Poncet ◽  
Benjamin Doistau ◽  
Céline Besnard ◽  
Claude Piguet
Keyword(s):  
Excited State ◽  
Quantum Yield ◽  
Quantum Yields ◽  
High Quantum ◽  
Excited State Lifetimes ◽  
Chelate Rings

Heteroleptic CrIII complexes combining tridentate 6-membered chelate rings: enhancing quantum yield and excited state lifetimes.

Could Hydrogen Peroxide Photolysis Occur in the Absence of Transition Metals ?

1981 ◽  
Vol 36 (5) ◽  
pp. 654-655 ◽  
Author(s):  
Stanislav Luňák ◽  
Josef Vepřek-Šiška
Keyword(s):  
Hydrogen Peroxide ◽  
Transition Metal ◽  
Reaction System ◽  
Transition Metal Ions ◽  
Quantum Yields ◽  
Complexing Agents ◽  
Square Root ◽  
Catalytically Active ◽  
Active Transition ◽  
Trace Concentrations

Quantum yields of hydrogen peroxide photolysis increase with the square root of concentration of added Cu(II). The cupric ions are photo-catalytically active already at trace concentrations (10-7), i.e., at the concentrations present in any real reaction system. Hydrogen peroxide photolysis is completely suppressed on addition of complexing agents such as EDTA. It is believed that no hydrogen peroxide photolysis would occur in complete absence of photo-catalytically active transition metal ions

Hydrogen peroxide photolysis. Mechanism of photocatalytic effect of transition metals

1983 ◽  
Vol 48 (11) ◽  
pp. 3033-3040 ◽  
Author(s):  
Stanislav Luňák ◽  
Josef Vepřek-Šiška
Keyword(s):  
Hydrogen Peroxide ◽  
Reaction System ◽  
Transition Metal Ions ◽  
Thermal Reaction ◽  
Oxidation States ◽  
Photochemical Reduction ◽  
Photocatalytic Effect ◽  
Catalytically Active ◽  
Photochemical Decomposition ◽  
Catalytic Cycles

The photochemical decomposition of hydrogen peroxide depends on the presence of transition metal ions in the reaction system. Photochemical reduction of the poorly catalytically active ions with higher oxidation states produces catalytically active ions of lower oxidation states which catalyze the thermal reaction. The quantum yield of hydrogen peroxide photolysis is proportional to the number of catalytic cycles occurring on the photochemically generated catalyst.

A robust and luminescent covalent organic framework as a highly sensitive and selective sensor for the detection of Cu2+ions

2016 ◽  
Vol 52 (39) ◽  
pp. 6613-6616 ◽  
Author(s):  
Zhongping Li ◽  
Yuwei Zhang ◽  
Hong Xia ◽  
Ying Mu ◽  
Xiaoming Liu
Keyword(s):  
Quantum Yield ◽  
Copper Ions ◽  
Luminescent Probe ◽  
High Quantum Yield ◽  
Covalent Organic Framework ◽  
High Quantum ◽  
Highly Sensitive ◽  
Excellent Stability ◽  
Selective Sensor ◽  
Organic Framework

A highly crystalline and porous azine-linked covalent organic framework possesses excellent stability and luminescence properties with high quantum yield. It can serve as a promising luminescent probe for selectively sensing copper ions.

Ultrastable g-C3N4 assemblies with high quantum yield and reversible photoluminescence

2018 ◽  
Vol 54 (96) ◽  
pp. 13519-13522 ◽  
Author(s):  
Zhixiang Jiang ◽  
Xiao Zhang ◽  
Junpeng Wang ◽  
Ling Chen ◽  
Hsueh-Shih Chen ◽  
...  
Keyword(s):  
Quantum Yield ◽  
High Stability ◽  
Quantum Yields ◽  
High Quantum Yield ◽  
High Quantum ◽  
First Time

Ultrastable g-C3N4 assemblies consisting of amorphous/crystalline nanosheets with high quantum yields up to 78% were prepared for the first time. A reversible photoluminescence was observed from green to blue once the pH was adjusted. These assemblies exhibit high stability in PL devices.

scholarly journals Improved photodecarboxylation properties in zinc photocages constructed using m-nitrophenylacetic acid variants

2021 ◽  
Author(s):  
Austin Shigemoto ◽  
Avik Bhattacharjee ◽  
Erin Hickey ◽  
Hallee Boyd ◽  
Theresa McCormick ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Quantum Yield ◽  
Photophysical Properties ◽  
Quantum Yields ◽  
Biological Applications ◽  
High Quantum Yield ◽  
High Quantum ◽  
Derivatives Of ◽  
Fluoro Derivatives

The methoxy- and fluoro-derivatives of meta-nitrophenylacetic acid (mNPA) chromophores undergo photodecarboxylation with comparable quantum yields to unsubstituted mNPA, but uncage at red-shifted excitation wavelengths. This observation prompted us to investigate DPAdeCageOMe (2-[bis(pyridin-2-ylmethyl)amino]-2-(4-methoxy-3-nitrophenyl)acetic acid) and DPAdeCageF (2-[bis(pyridin-2-ylmethyl)amino]-2-(4-fluoro-3-nitrophenyl)acetic acid) as Zn2+ photocages. DPAdeCageOMe has a high quantum yield and exhibits other photophysical properties comparable to XDPAdeCage ({bis[(2-pyridyl)methyl]amino}(9-oxo-2-xanthenyl) acetic acid), the best perforiming Zn2+ photocage reported to date. Since the synthesis of DPAdeCageOMe is more straightforward than XDPACage, the new photocage will be a highly competitive tool for biological applications.

High quantum yield and unusual photoluminescence behaviour in tetrahedral manganese(ii) based on hybrid compounds

2018 ◽  
Vol 5 (10) ◽  
pp. 2615-2619 ◽  
Author(s):  
Yan-Li Wei ◽  
Jing Jing ◽  
Chao Shi ◽  
Heng-Yun Ye ◽  
Zhong-Xia Wang ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Quantum Yields ◽  
Organic Cations ◽  
High Quantum Yield ◽  
Hybrid Compounds ◽  
High Quantum ◽  
Luminescence Characteristics

High quantum yields and unusual luminescence characteristics were successfully achieved by regulating the organic cations in tetrahedral manganese(ii) complexes.

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