Quantum yield evidence for a chain reaction in the photochemical decomposition of phenyl azide

1982 ◽  
Vol 104 (21) ◽  
pp. 5804-5805 ◽  
Author(s):  
Walter H. Waddell ◽  
Celia H. Lee
Keyword(s):  
Quantum Yield ◽  
Chain Reaction ◽  
Phenyl Azide ◽  
Photochemical Decomposition ◽  
A Chain

The photolysis of ozone by ultraviolet radiation. I. The photolysis of pure, dry ozone

1965 ◽  
Vol 288 (1413) ◽  
pp. 200-211 ◽  
Keyword(s):  
Reaction Mechanism ◽  
Quantum Yield ◽  
Light Intensity ◽  
Ultraviolet Radiation ◽  
Oxygen Molecule ◽  
Inert Gases ◽  
Ozone Variation ◽  
Photochemical Decomposition ◽  
A Chain ◽  
Limiting Value

The photochemical decomposition of dry ozone has been studied at λ = 2537 Å. The quantum yield for the photolysis of pure ozone was proportional to the pressure of ozone; the highest quantum yield recorded was 16.7 at a pressure of 5 cmHg ozone. Variation of light intensity did not markedly affect the quantum yield, and some evidence was found for a wall termination reaction. A reaction mechanism is proposed in which O( 1 D ) atoms, formed in the primary photolysis, initiate a chain propagated by energy-rich oxygen molecules. A discussion of the nature of the energy-rich molecules is presented. Addition of inert gases to the pure ozone reduces the quantum yield to a limiting value of two. This is explained in terms of the deactivation of the energy-rich oxygen molecule. In the presence of oxygen, the quantum yield tends to zero, as a result of the reverse reaction O + O 2 + M → O 3 + M .

scholarly journals The photochemistry of phosphine

1932 ◽  
Vol 138 (835) ◽  
pp. 374-395 ◽  
Keyword(s):  
Experimental Data ◽  
Absorption Spectrum ◽  
Photochemical Reactions ◽  
Metallic Elements ◽  
Chain Reaction ◽  
Photo Oxidation ◽  
Considerable Success ◽  
Photochemical Decomposition ◽  
The Subject ◽  
A Chain

Within recent years the spectroscopy and the photochemistry of the hydrides of the non-metallic elements has been the subject of much study and the results explained with considerable success on the basis of the newer theories of photochemical reactions. In spite of the fact that the photochemistry of ammonia has attracted some attention, yet the investigation of the equally simple molecule of phosphine seems to have been entirely neglected. It is with the object of filling this gap in photochemistry that the present experiments have been undertaken. The investigation naturally falls into three parts: ( a ) the absorption spectrum of phosphine, ( b ) the direct photochemical decomposition, ( c ) the photosensitised decomposition. Experimental data on the photo-oxidation are also of importance in view of the fact that the thermal oxidation of phosphine is a chain reaction.

The photochemical decomposition of t -butyl hydroperoxide in solution

1953 ◽  
Vol 220 (1142) ◽  
pp. 322-339 ◽  
Keyword(s):  
Quantum Yield ◽  
Wave Length ◽  
Butyl Alcohol ◽  
Quantum Yields ◽  
Oxidation Reactions ◽  
Butyl Hydroperoxide ◽  
Acetone Water ◽  
Photochemical Decomposition ◽  
Solvent Molecules ◽  
A Chain

The photochemical decomposition of t -butyl hydroperoxide by light of wave-length 3130 Å has been investigated in three solvents. Reaction mechanisms are elucidated by consideration of the products and the quantum yields of decomposition. In carbon tetrachloride a chain reaction occurs in which the quantum yield of 3.2 at 20° C increases to 5.3 at 50° C. The main products are t -butyl alcohol and oxygen with smaller amounts of acetone, water and compounds arising from the oxidation of methyl radicals. The same series of reactions takes place in n -hexane, but superimposed are oxidation reactions involving solvent molecules which ultimately lead to the formation of alcohols. The quantum yield in this solvent is 3.9 and independent of temperature. When the peroxide is irradiated in dioxan solution immediate hydrogenation of the radicals produced in the primary photo-chemical act prevents the formation of reaction chains and the quantum yield is unity. The interaction of the radicals with solvent molecules is such that some of the etheric oxygen of the dioxan is transformed into alcoholic hydroxyl during the course of the reaction, and the fragmentation of dioxan gives formaldehyde Experiments with a dioxan solution using light of wave-length 2450 to 2800 Å show no fundamental change in the mode of decomposition of the peroxide, but an increase in concentration of the products of dioxan decomposition indicates a more vigorous attack by the radicals on the solvent.

The photolysis of ozone by ultraviolet radiation. II. The photolysis of ozone mixed with certain hydrogen-containing substances

1965 ◽  
Vol 288 (1414) ◽  
pp. 361-370 ◽  
Keyword(s):  
Quantum Yield ◽  
Ultraviolet Radiation ◽  
Hydroxyl Radical ◽  
Hydrogen Chloride ◽  
Water Vapour ◽  
Kinetic Scheme ◽  
Chain Reaction ◽  
Secondary Reactions ◽  
A Chain ◽  
Experimental Findings

The quantum yield of the photolysis of ozone at λ = 2537 Å has been determined in the presence of water vapour, hydrogen, methane, hydrogen chloride and ammonia. In each case, the quantum yield determined was greater than that for pure ozone, and it is suggested that 1 D oxygen atoms formed in the primary photolytic step are able to react with the added gas to form a hydroxyl radical which is then able to propagate a chain reaction. A general kinetic scheme, consistent with the experimental findings, is presented, and the secondary reactions in the several cases are discussed.

The photochemistry of aqueous solutions of Tl(III) perchlorate

1970 ◽  
Vol 48 (19) ◽  
pp. 2955-2959 ◽  
Author(s):  
C. E. Burchill ◽  
W. H. Wolodarsky
Keyword(s):  
Charge Transfer ◽  
Quantum Yield ◽  
Flash Photolysis ◽  
Primary Process ◽  
Chain Reaction ◽  
Perchloric Acid Solution ◽  
Upper Limit ◽  
Aqueous Perchloric Acid ◽  
A Chain ◽  
A Charge

In deaerated aqueous perchloric acid solution Tl(III) is reduced and 2-propanol oxidized to acetone in equivalent yields via a chain reaction initiated by light of 2537 Å. Initiation is attributed to a charge-transfer-to-metal excitation followed by dissociation[Formula: see text]The formation of Tl(II) in the primary process is demonstrated by flash photolysis. An upper limit of 0.36 ± 0.07 is estimated for the primary quantum yield.

Observations on a Relationship between Steroid Metabolism and the Concentration of Plasma Fibrinogen

1963 ◽  
Vol 10 (02) ◽  
pp. 400-405 ◽  
Author(s):  
B. A Amundson ◽  
L. O Pilgeram
Keyword(s):  
Blood Coagulation ◽  
Methyl Ether ◽  
Broad Spectrum ◽  
Human Subjects ◽  
Plasma Fibrinogen ◽  
Steroid Metabolism ◽  
Specific Site ◽  
Chain Reaction ◽  
Normal Human ◽  
A Chain

SummaryEnovid (5 mg norethynodrel and 0.075 mg ethynylestradiol-3-methyl ether) therapy in young normal human subjects causes an increase in plasma fibrinogen of 32.4% (P >C 0.001). Consideration of this effect together with other effects of Enovid on the activity of specific blood coagulatory factors suggests that the steroids are exerting their effect at a specific site of the blood coagulation and/or fibrinolytic system. The broad spectrum of changes which are induced by the steroids may be attributed to a combination of a chain reaction and feed-back control.

scholarly journals Pathogenesis and Management of COVID-19

2021 ◽  
Vol 11 (2) ◽  
pp. 77-93
Author(s):  
Khalid O. Alfarouk ◽  
Sari T. S. AlHoufie ◽  
Samrein B. M. Ahmed ◽  
Mona Shabana ◽  
Ahmed Ahmed ◽  
...  
Keyword(s):  
Multiple Organ Failure ◽  
Human Body ◽  
Inflammatory Mediators ◽  
Expression Patterns ◽  
Multiple Organ ◽  
Cytokine Storm ◽  
Chain Reaction ◽  
Road Map ◽  
A Chain ◽  
Global War

COVID-19, occurring due to SARS-COV-2 infection, is the most recent pandemic disease that has led to three million deaths at the time of writing. A great deal of effort has been directed towards altering the virus trajectory and/or managing the interactions of the virus with its subsequent targets in the human body; these interactions can lead to a chain reaction-like state manifested by a cytokine storm and progress to multiple organ failure. During cytokine storms the ratio of pro-inflammatory to anti-inflammatory mediators is generally increased, which contributes to the instigation of hyper-inflammation and confers advantages to the virus. Because cytokine expression patterns fluctuate from one person to another and even within the same person from one time to another, we suggest a road map of COVID-19 management using an individual approach instead of focusing on the blockbuster process (one treatment for most people, if not all). Here, we highlight the biology of the virus, study the interaction between the virus and humans, and present potential pharmacological and non-pharmacological modulators that might contribute to the global war against SARS-COV-2. We suggest an algorithmic roadmap to manage COVID-19.

Influence of initiation mode on stability and control of a chain reaction

1980 ◽  
Vol 20 (18) ◽  
pp. 1197-1204 ◽  
Author(s):  
H. T. Chen ◽  
P. A. Chartier ◽  
S. Setthachayanon
Keyword(s):  
Chain Reaction ◽  
Stability And Control ◽  
A Chain ◽  
And Control

Exposure of squalene hydroperoxides to photons causes the formation of unique squalene cyclic peroxides via a chain reaction mechanism detected on the human skin and causing harm to skin cells (HaCaT)

2021 ◽  
Author(s):  
Saoussane Khalifa ◽  
Masaru Enomoto ◽  
Takahiro Eitsuka ◽  
Kiyotaka Nakagawa ◽  
Yurika Otoki ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Human Skin ◽  
Chain Reaction ◽  
Skin Cells ◽  
A Chain
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