RADIATION CHEMISTRY OF CYCLOHEXANE: III. EFFECT OF BENZENE AND IODINE ON THE ISOTOPIC COMPOSITION OF RADIOLYTIC HYDROGEN FROM C6D12–C6H12 MIXTURES

1961 ◽  
Vol 39 (11) ◽  
pp. 2163-2170 ◽  
Author(s):  
P. J. Dyne ◽  
W. M. Jenkinson
Keyword(s):  
Isotopic Composition ◽  
Radiation Chemistry ◽  
Bimolecular Reaction ◽  
Specific Yield ◽  
Unimolecular Decomposition ◽  
Common Precursor

The isotopic composition of hydrogen evolved in the radiolysis of C6D12–C6H12 mixtures has been measured in the presence of various amounts of benzene and iodine. The yield of the unimolecular decomposition and the specific yield of the bimolecular reaction are reduced in approximately the same proportion as the yield of total hydrogen. It is concluded that (i) iodine and benzene interact to a comparable extent with both unimolecular and bimolecular decomposition modes, (ii) it is probable that neither of these additives act by scavenging, and (iii) it is probable that they act by quenching a common precursor of the two decomposition modes.

The radiation chemistry of aqueous solutions of nitrous oxide

1965 ◽  
Vol 285 (1402) ◽  
pp. 339-359 ◽  
Keyword(s):  
Nitrous Oxide ◽  
Steady State ◽  
Aqueous Solutions ◽  
Dose Rate ◽  
Radiation Chemistry ◽  
Bimolecular Reaction ◽  
Unimolecular Decomposition ◽  
Solvated Electron ◽  
Concentrated Aqueous Solutions ◽  
Dose Effects

For carefully purified concentrated aqueous solutions of N 2 0, G (N 2 ) is initially greater than the steady state value of 3.0 and G (O 2 ) less than the steady state value of 1.45 when G (H 2 ) = G (H 2 O 2 ) = 0. For very dilute solutions G (N 2 ) is small, independent of dose rate and decreases with increasing dose and decreasing [N 2 O], while G (H 2 ) is initially > 0.45, independent of dose rate and decreases with dose. The high initial G (H 2 is not due to organic or other impurity and is thought to arise either from bimolecular reaction of e aq − . and H within a spur or track or from unimolecular decomposition of the solvated electron either to H 2 + O - or H + OH - or from a combination of both. The dose effects are attributed to competitive scavenging of e aq − . by H 2 O 2 as the latter is produced.

A shock-tube study of the kinetics of decomposition of carbon disulphide

1964 ◽  
Vol 279 (1378) ◽  
pp. 313-326 ◽  
Keyword(s):  
Carbon Disulphide ◽  
Bimolecular Reaction ◽  
Second Order ◽  
Unimolecular Decomposition ◽  
Type D ◽  
Rate Determining Step ◽  
Collision Partner ◽  
Kinetics Of ◽  
Crossing Point ◽  
Tube Study

The rate of decomposition of carbon disulphide in shock waves through CS 2 + Ar mixtures has been studied spectroscopically between 2250 and 3350 °K. Mainly, the rate of appearance of CS has been measured, but in some instances it has been possible also to follow the rate of appearance of S 2 and the rate of disappearance of CS 2 . The rate obeys mixed second-order kinetics of the type –d[CS 2 ]/d t = k ∞ [Ar] [CS 2 ] + k 0 [CS 2 ] 2 . The term that is second-order in [CS 2 ] appears to correspond to a unimolecular decomposition of the CS 2 in which the collision partner is another CS 2 , rather than to a true bimolecular reaction. k 0 is found to be about 20 times as large as k ∞ . The rate constant for decomposition at infinite dilution in argon is given in Arrhenius form by k ∞ = 10 15.9 exp ( – 81.8 kcal/ RT ) cm 3 mole -1 s -1 . The application of R. R. K. H. theory to this yields as the most probable result, k ∞ = ( PZ /3!) (96 kcal/ RT ) 3 exp ( – 96 kcal/ RT ), in which P is about 0.1. Thus four effective oscillators may be contributing energy to the decomposition process, the rate-determining step of which is likely to be a transition from the ground state to an excited singlet state at a crossing point located at an energy of about 96 kcal. In this respect CS 2 is an interesting contrast to CO 2 , where the transition is probably singlet-triplet. The firmness of these conclusions is limited by the scarcity of knowledge concerning excited electronic states of CS 2 .

RADIATION CHEMISTRY OF CYCLOHEXANE: I. ISOTOPIC COMPOSITION OF HYDROGEN EVOLVED FROM MIXTURES OF C6D12 AND C6H12

1960 ◽  
Vol 38 (4) ◽  
pp. 539-543 ◽  
Author(s):  
P. J. Dyne ◽  
W. M. Jenkinson
Keyword(s):  
Isotopic Composition ◽  
Radiation Chemistry ◽  
A Value ◽  
Γ Ray

The yield of D2 formed by a unimolecular process in the γ-ray irradiation of cyclohexane-d12 has been deduced from the isotopic composition of hydrogen evolved from C6H12–C6D12 mixtures. A value of 0.25 molecule/100 ev is found for this "molecular" yield. This yield is only slightly reduced by iodine but is considerably reduced in the presence of biphenyl.

Radiation Chemistry

1975 ◽  
Vol 94 (4-6) ◽  
pp. 333-333
Author(s):  
K.-D. Asmus
Keyword(s):  
Radiation Chemistry

Simple Modification Measurement of Photodegradability of Polymers by using Photo-induced Chemiluminescence Technique

2013 ◽  
Vol 10 (2) ◽  
pp. 51
Author(s):  
Siti Farhana Zakaria ◽  
Keith R Millington
Keyword(s):  
Free Radicals ◽  
Organic Materials ◽  
Oxidative Degradation ◽  
Working Life ◽  
Bimolecular Reaction ◽  
Synthetic Polymers ◽  
Accelerated Weathering ◽  
Simple Modification ◽  
Uv Absorbers ◽  
Irradiation Period

Polymers and organic materials that are exposed to sunlight undergo photooxidation, which leads to deterioration of their physical properties. To allow adequate performance under outdoor conditions, synthetic polymers require additives such as antioxidants and UV absorbers. A major problem with optimising polymer formulations to maximise their working life span is that accelerated weathering tests are empirical. The conditions differ significantly from real weathering situations, and samples require lengthy irradiation period. Degradation may not be apparent in the early stages of exposure, although this is when products such as hydroperoxides are formed which later cause acceleration of oxidation. A simple way of quantifying the number of free radicals presents in organic materials following exposure to light or heat is by measuring chemiluminescence (CL) emission. Most polymers emit CL when they undergo oxidative degradation, and it originates from the bimolecular reaction of macroperoxy radicals which creates an excited carbonyl.

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