Photochemical studies of unimolecular processes V. The photolysis and quenching of
            cis-
            and
            trans
            hexa-1, 3, 5-triene and of cyclohexa-1, 3-diene

The photolyses of cis- and trans -hexa-1, 3, 5-triene at wavelengths of 228.8 and 253.7 nm and of cyclohexa-1, 3-diene at 265.4 and 280.4 nm have been studied in the gas phase at various pressures and in the presence of added gases. At low pressures, the limiting quantum yield for hexatriene photolysis is unity within experimental error, and it is shown that the pressure dependence of all the observed interconversions of C 6 H 8 isomers and of benzene formation can be explained by reactions of vibrationally excited molecules produced by very rapid internal conversion.

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Relaxation and chemical reaction of vibrationally excited molecules in the gas phase

Journal of Molecular Structure ◽

10.1016/0022-2860(80)85075-7 ◽

1980 ◽

Vol 59 ◽

pp. 207-224 ◽

Cited By ~ 10

Author(s):

M. Kneba ◽

R. Stender ◽

U. Wellhausen ◽

J. Wolfrum

Keyword(s):

Gas Phase ◽

Chemical Reaction ◽

Vibrationally Excited ◽

Excited Molecules

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The role of excited states in the gas-phase photolysis of acetaldehyde

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1973.0100 ◽

1973 ◽

Vol 334 (1598) ◽

pp. 411-426 ◽

Cited By ~ 15

Keyword(s):

Triplet State ◽

Gas Phase ◽

Excited States ◽

Product Formation ◽

Vibrationally Excited ◽

Liquid Phases ◽

Radical Decomposition ◽

A Chain ◽

Low Pressures

The cis-trans isomerization of butene-2 has been used to measure the triplet state yields in the photolysis of acetaldehyde at various wavelengths between 313 and 254 nm over the temperature range 35 to 140 °C. The results, together with those derived from chemical product formation, are consistent with data from luminescence studies. Dissociation into molecular products occurs rapidly, probably by predissociation, from a non-quenchable excited state formed by absorption. The main free radical decomposition occurs from the triplet state and this, in the absence of additives, such as butene-2, is responsible for the chain decomposition. The intersystem crossing and non-quenchable processes are independent of temperature. Isopentyl radicals formed from methyl addition to butene-2 can also propagate a chain reaction for acetaldehyde decomposition. At high temperatures and low pressures, dissociation of vibrationally excited isopentyl radicals can contribute to the measured isomerization yield. This is shown by the effect of addition of inert gas. Evidence is put forward that geometrical isomerization of the olefin involves a triplet aldehyde-olefin complex that can be decomposed by collision with ground state aldehyde molecules without cis-trans rearrangement of the olefin. This conclusion is consistent with other work in the gas and liquid phases.

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The α(C—C)/β(C—H) ratio of the primary processes in the 184.9 nm photolysis of gaseous cis- and trans-2-butene

Canadian Journal of Chemistry ◽

10.1139/v87-273 ◽

1987 ◽

Vol 65 (7) ◽

pp. 1631-1638 ◽

Cited By ~ 2

Author(s):

Hélène Deslauriers ◽

Wlodzimiercz Makulski ◽

Guy J. Collin

Keyword(s):

Quantum Yield ◽

Gas Phase ◽

Molecular Property ◽

Bond Rupture ◽

Complete Study ◽

Yield Values ◽

In Trans ◽

Cis And Trans ◽

In Cis

A complete study of the 184.9 nm photolysis of cis- and trans-2-butene has been done in the gas phase. The main primary processes (>90%) are the α(C—C) and β(C—H) bond ruptures. Both processes have similar quantum yield values in cis-2-butene: [Formula: see text]. Conversely, the α(C—C) bond rupture is more important in trans-2-butene: [Formula: see text]. These values are compared with those measured in propene (0.57) and isobutene (0.95). No simple molecular property seems sufficient to explain such an effect.

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UPS Spectra of Cis and Trans 1-Phenyl-2-(4-Pyridyl) Cyclopropanes. A Comparison with Charge Transfer and Protonation Data

Zeitschrift für Naturforschung A ◽

10.1515/zna-1979-0219 ◽

1979 ◽

Vol 34 (2) ◽

pp. 245-247

Author(s):

G. Distefano ◽

A. Modelli ◽

V. Mancini

Keyword(s):

Charge Transfer ◽

Gas Phase ◽

Ionization Energy ◽

Energy Region ◽

Experimental Error ◽

Two Phases ◽

Cis And Trans

AbstractThe low ionization energy region of the USP spectra of cis- and trans-1-(4-X-phenyl)-2-(4pyridyl) cyclopropanes is assigned by analogy with those of simple related molecules. Corresponding IE values of cis and trans derivatives are equal within the limits of experimental error. This finding indicates, at variance with solution results previously obtained, that in the gas phase there is no sizeable through- space interaction between the MO’s of the two cis-aryl groups. A possible explanation of the different conformations of the cis derivatives in the two phases is proposed

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