Photolyse des Äthylens im Bereich 147 — 193 nm / Ethylene Photolysis At 147 — 193

Potzinger, P.; Glasgow, L. C.; Bünau, Günther von

doi:10.1515/zna-1972-0415

Cited by 37 publications

(25 citation statements)

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“…This intensity was much lower than used in previous studies; in particular in the study by Potzinger et al the absorbed intensity was 1.7 x 1017 quanta 1-' s-' (13). The lower light intensity caused two differences between the mechanism outlined here and that proposed in the latter study.…”

Section: Resultscontrasting

confidence: 55%

“…The photolysis of ethylene at 185 nm has been shown to involve three primary processes and it has been suggested that at least three excited states of ethylene contribute to these reactions (13). Deactivation without decomposition is also important at 185 nm.…”

Section: Resultsmentioning

confidence: 99%

“…In the measurement of such a small temperature coefficient some advantage may be gained by making measurements at low temperatures. To accomplish this with a gas phase reaction we have studied the photolysis of ethylene at 185 nm over the temperature range 298-153 K. Several studies of this reaction (13)(14)(15)(16) have shown that at least one primary process involves the formation of a hydrogen atom which rapidly adds to ethylene to form an ethyl radical. Subsequent reactions of the ethyl radical, which at low temperatures are mainly radical-radical reactions, may be studied.…”

Section: Introductionmentioning

confidence: 99%

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The Temperature Dependence of the Ratio k_d/k_c for Ethyl Radicals

Hooper¹,

Simon²,

Back³

1975

Can. J. Chem.

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The ratio of the rate constants for disproportionation and combination for ethyl radicals, k d / k kd 2C2Hs + C2H4 + C2Hs has been measured over the temperature range 298-173 K in the gas phase. Ethyl radicals were produced by direct photolysis of ethylenefollowed by addition of hydrogen atoms to ethylene. At low temperatures the only important reactions of the radicals were combination and disproportionation. The ratio kd/kc was obtained from measurements of the rates of formation of ethane, butane, and butene. No change in the ratio kd/k, was observed over the temperature range studied, leading to the conclusion that Ed -E, = 0, within the experimental error. The significance of this result is discussed in relation to other measurements in both gas and liquid phase and to the nature of the transition state for this reaction.

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Section: Resultscontrasting

confidence: 55%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Temperature Dependence of the Ratio k_d/k_c for Ethyl Radicals

Hooper¹,

Simon²,

Back³

1975

Can. J. Chem.

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“…At lower photon energies (5.6-6.2 e V) there IS barely enough energy for the occurrence of the overall process ! !.H=5_5eV (8) and the high relative yield of C2H2 can definitely be ascribed to the elimination of DCl from a single carbon atom:…”

Section: (4)mentioning

confidence: 97%

“…The quantum yields of the other products were determined by using ethylene (1.5 torr) as a chemical actinometer. The quantum yield of acetylene at 147 and 123.6 nm was established [7][8] to be 1 ± 0.05. At 104.8-106.7, <1>(C 2H2) has been estimated [9] to be 0.75 ± 0.05.…”

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confidence: 99%

Gas phase far ultraviolet photolysis and radiolysis of vinyl chloride

Ausloos

Rebbert

Wijnen

1973

J. RES. NATL. BUR. STAN. SECT. A.

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Quantum yi e lds of the major produ cts formed in the far ultravi ole t photolys is of CH,C DCI (C2 H2 , C, HD , C,HoD, C, H2 D" and 1,3·C, H,D,) have bee n de te rmin e d at 147 nm (8.4 e V), 123.6 nm (10.0 eV), a nd 104.8-106.7 nm 01.6-11.8 e V). The quantum yield of th e s tab le vinyl rad ica ls whi c h can be un· ambiguous ly asc ribed to the primary process (C H2CDCI + hll~ CH,C D+ CI) is 0.3 a nd 0.05 at 147 and 123.6 nm, res pe c tive ly. The sharp d ec rease in the yie ld of vinyl radicals with the in c re ase in e ne rgy of the in cid e nt photon beam is in part attribute d to the deco mposition of inte rnally e xcited vinyl radica ls to give acet yle ne as a produ c t. At 147 nm , th e co mbin ed yield of acet yle ne plu s vinyl rad icals is 0.95 ± 0.05. At the s horte r wa ve length s, approximate ly one acet yle ne molecul e is form ed per e lectronically excite d vinyl c hloride mol ec ule. It is conclude d that th e dissociative process: C2 HaCI* ~ C,H, + H + CI, occ urrin g via a C, Ha or C,H, CI inte rm e diate ade qu ate ly acco unts for the reo active ne utral s pecies form ed at higher photon e ne rgies. Isotopi c la belin g e xpe rim e nts s how that the hyd roge n atoms are d etac hed from both pos iti ons of th e pare nt molecule. Ethylene whic h is a produ ct over the e ntire wavel ength range is in part form e d via the reaction : H* + C,HaC I ~ C2H .. + CI, whe re H* re presents a translationa Uy e xcited hydrogen atom. The C2H2DC I+ ion s formed at 104.8 -106.7 nm with a quantum yie ld of 0.47 do not contribute to th e form ation of acetyle ne or vinyl radi c al s. In the gas phase radiolysis of vinyl c hlorid e, acetyl e ne (G -1. 5) is ma inly form e d in th e di ssocia tion of ne utra l e lectronica ll y excited vinyl c hlorid e molec ules. From this value, we may es tim ate th at the ratio of neutral excited molec ul es formation to ionization in th e rad iolys is of vinyl c hl orid e is 0.39. Vinyl ions, whi c h a re also prod uced (G -0.28-0.35) react ma inl y by addition to vi n yl c hlorid e.

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