Vacuum Ultraviolet Photolysis of Trimethylethylene

1974 ◽  
Vol 52 (1) ◽  
pp. 34-38 ◽  
Author(s):  
Guy J. Collin ◽  
Christian M. Gaucher
Keyword(s):  
Quantum Yield ◽  
Vacuum Ultraviolet ◽  
Radical Reactions ◽  
High Yield ◽  
Rare Gas ◽  
Static System ◽  
Hydrogen Atoms ◽  
Ultraviolet Photolysis ◽  
Ethyl Radicals ◽  
Secondary Carbon

The vacuum u.v. photolysis of trimethylethylene (2-methyl-2-butene) was carried out in a static system using rare gas resonance lamps: xenon (147.0 nm) and krypton (123.6 nm). The main hydrocarbon products were isoprene, 1,3-butadiene, propyne, allène, ethylene, and other minor products. Identification and measurements of the yields of hydrogen atoms, methyl, and ethyl radicals were carried out quantitatively by the use of radical–radical reactions. Because of the high yield of isoprene, the effect of conversion was studied. At a high conversion (i.e. 0.1%) the isoprene quantum yield decreases. Hydrogen atoms add mainly to the secondary carbon of the monomer (≥90%). The Δ(CH3,tert-C5H11) value was calculated to be 1.32 ± 0.14. With the krypton line (10.0 eV) no evidence was found for the participation of ionic reactions in the formation of the measured products except for the formation of 2-methyl-1-butene in a low yield. At this wavelength the ion quantum yield is 0.224 ± 0.005.

The vacuum ultraviolet photolysis of hydrogen chloride. The role of the hot hydrogen atoms

1981 ◽  
Vol 55 (1-2) ◽  
pp. 9-15 ◽  
Author(s):  
A. Jówko ◽  
S. U. Pavlova ◽  
H. Baj ◽  
B. G. Dzantiev ◽  
M. Foryś
Keyword(s):  
Hydrogen Chloride ◽  
Vacuum Ultraviolet ◽  
Hydrogen Atoms ◽  
Ultraviolet Photolysis

Vacuum–ultraviolet photolysis (185 nm) of liquid 1,3-dioxan

1985 ◽  
Vol 63 (7) ◽  
pp. 1833-1839 ◽  
Author(s):  
Heinz-Peter Schuchmann ◽  
Clemens von Sonntag
Keyword(s):  
Molecular Weight ◽  
Liquid Phase ◽  
Quantum Yield ◽  
General Type ◽  
Vacuum Ultraviolet ◽  
Vapour Phase ◽  
Side Chain ◽  
Low Molecular Weight ◽  
Type B ◽  
Ultraviolet Photolysis

1,3-Dioxan photolytic destruction at 185 nm occurs with a quantum yield of about 0.3 in the liquid phase. Of the 22 products determined, the major ones are n-propylformate [Formula: see text], formaldehyde (0.075), 1,3-diox-4-en (0.06), hydrogen (0.05), ethylene (0.04), and 3-methoxypropionaldehyde (0.04). A number of the minor products are of the general type B.[Formula: see text]some of which bear a hydroxyl function at the end of the side chain. N2O interacts with excited 1,3-dioxan, leading to the production of N2.Some experiments have been carried out in the vapour phase, the results of which indicate that considerable fragmentation of hot primary intermediates and products into low-molecular-weight products occurs. The nature of these products cannot be linked directly to the primary photolytic processes inferred from the liquid-phase studies.Certain contrasts in the photolytic behaviour of 1,3-dioxan and 1,4-dioxan are discussed.

Mécanisme de la décomposition photosensibilisée au mercure du méthylvinyléther à 2537 Å

1971 ◽  
Vol 49 (12) ◽  
pp. 2125-2131 ◽  
Author(s):  
J. Castonguay ◽  
Y. Rousseau
Keyword(s):  
Free Radical ◽  
Quantum Yield ◽  
Vinyl Ether ◽  
Radical Reactions ◽  
Second Primary ◽  
Primary Process ◽  
Static System ◽  
Free Radical Reactions ◽  
Methyl Vinyl ◽  
Methyl Vinyl Ether

The study of the mercury Hg6(3P1) photosensitized decomposition of methyl vinyl ether has been studied in a static system at substrate pressures from 10 to 800 Torr. The excited precursor proposed has a calculated lifetime of 1.18 × 10−10 s and its decomposition proceeds almost exclusively through the rupture of the O—CH3 bond. A second primary process is the intramolecular formation of ethylene but it accounts only for 2% of the total ether decomposition. The major products are shown to be formed by free radical reactions and the overall reactivity appears to be very similar to that of the olefins. The results obtained with CH3SH added to the system indicate that the primary radicals are formed with a quantum yield close to unity.

The Vacuum Ultraviolet Photolysis of Cyclopentanone

1972 ◽  
Vol 50 (24) ◽  
pp. 3938-3943 ◽  
Author(s):  
Alfred A. Scala ◽  
Daniel G. Ballan
Keyword(s):  
Quantum Yield ◽  
Carbonyl Group ◽  
Incident Energy ◽  
Vacuum Ultraviolet ◽  
Quantum Yields ◽  
Electronically Excited ◽  
Ultraviolet Photolysis

In the vacuum ultraviolet photolysis of cyclopentanone, the major modes of fragmentation of the electronically excited ketone are:[Formula: see text]The sum of the quantum yields for reactions A and B is 0.87 at 147.0 nm and these reactions become less important as the incident energy is increased. A pressure study at 147.0 nm of the partitioning of the tetramethylene diradical between paths A and B indicates that the ratio kA/kB is approximately 8. The quantum yield for reaction 8 is only 0.02. The remainder of the decomposition of cyclopentanone is accounted for by reactions 4 and 5, which appear to become more significant as the incident energy increases. The mechanisms for reactions 6 and 8 are best interpreted in terms of diradicals of structure (CH2)n where n = 1, 3, and 4. The lack of non-acyl σ-cleavage at 147.0 nm is an indication that the absorption of energy occurs at the carbonyl group.

Nuclear Recoil Reactions in Organo-Manganese Compounds. V. —Mn(CO)5 Target Compounds

1971 ◽  
Vol 49 (12) ◽  
pp. 2175-2178 ◽  
Author(s):  
H. Jakubinek ◽  
S. C. Srinivasan ◽  
D. R. Wiles
Keyword(s):  
Thermal Dissociation ◽  
Nuclear Recoil ◽  
Radical Reactions ◽  
High Yield ◽  
Target Molecule ◽  
Product Spectrum ◽  
Rapid Exchange ◽  
Manganese Compounds ◽  
Very High

HMn(CO)5, DMn(CO)5, CH3Mn(CO)5, and C6H5Mn(CO)5 have been irradiated with neutrons and the product spectrum of 56Mn-containing molecules determined. The results show that H56Mn(CO)5 is formed in all cases: 21.0%, 23.6% from HMn(CO)5 and DMn(CO)5 targets, respectively, and 6.9% and 2.1% from CH3Mn(CO)5 and C6H5Mn(CO)5, respectively. Thus the yields are not in accord with the number of H atoms per target molecule. Preliminary experiments show that •*Mn(CO)5 exchanges rapidly with HMn(CO)5 and DMn(CO)5 and very slowly with CH3Mn(CO)5 and C6H5Mn(CO)5. It is deduced that the very high yield of H56Mn(CO)5 in HMn(CO)5 and DMn(CO)5 targets could arise from the rapid exchange, while the lower yields of H56Mn(CO)5 in other targets must likely come from radical reactions following thermal dissociation of the target molecule.

Hg(63P1)-sensitized decomposition of HNCO vapor and HNCO–H2 mixtures; the reaction of hydrogen atoms with HNCO

1968 ◽  
Vol 46 (4) ◽  
pp. 527-530 ◽  
Author(s):  
N. J. Friswell ◽  
R. A. Back
Keyword(s):  
Quantum Yield ◽  
Cross Section ◽  
Initial Step ◽  
Primary Process ◽  
Hydrogen Atoms ◽  
Direct Photolysis ◽  
A Value ◽  
The Cross

The Hg(63P1)-sensitized decomposition of HNCO vapor has been briefly studied at 26 °C with HNCO pressures from about 3 to 30 Torr. The products detected were the same as in the direct photolysis, CO, N2, and H2. The quantum yield of CO was appreciably less than unity, compared with a value of 1.5 in the direct photolysis under similar conditions. From this and other observations it is tentatively concluded that a single primary process occurs:[Formula: see text]From a study of the mercury-photosensitized reactions in mixtures of HNCO with H2, it was concluded that hydrogen atoms react with HNCO to form CO but not N2. The initial step is probably addition to form NH2CO. From the competition between reaction [1] and the corresponding quenching by H2, the cross section for reaction [1] was estimated to be 2.3 times that of hydrogen.

Production of Metastable Hydrogen Atoms in Proton—Rare-Gas Collisions

1965 ◽  
Vol 137 (2A) ◽  
pp. A340-A346 ◽  
Author(s):  
D. Jaecks ◽  
B. Van Zyl ◽  
R. Geballe
Keyword(s):  
Rare Gas ◽  
Hydrogen Atoms
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