The Primary Quantum Efficiency of Free Radical Formation in Acetaldehyde Photolysis at 3130 Å.

Calvert, Jack G.; Pitts, James N.; Thompson, Donald D.

doi:10.1021/ja01598a013

Cited by 13 publications

(3 citation statements)

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“…Photolysis of acetaldehyde at 308 nm occurs primarily via channel 2a. [36][37][38][39][40][41][42][43][44][45][46] Minor channel 2b produces methane and carbon monoxide, which do not lead to any kinetic interference under the experimental conditions of the current study.…”

Section: Methodsmentioning

confidence: 73%

“…Formyl radicals were prepared by pulsed photolysis of acetaldehyde and propionaldehyde at 308 nm (XeCl excimer laser): Photolysis of acetaldehyde at 308 nm occurs primarily via channel 2a. − Minor channel 2b produces methane and carbon monoxide, which do not lead to any kinetic interference under the experimental conditions of the current study.…”

Section: Methodsmentioning

confidence: 99%

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Unimolecular Dissociation of Formyl Radical, HCO → H + CO, Studied over 1−100 Bar Pressure Range

Krasnoperov¹,

Чесноков

Stark

et al. 2004

J. Phys. Chem. A

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Unimolecular dissociation of formyl radical, HCO → H + CO (1), was studied using pulsed laser photolysis coupled to transient UV−vis absorption spectroscopy. One-pass UV absorption, multipass UV absorption, and cavity ring down spectroscopy in the red spectral region were used to monitor temporal profiles of the HCO radical. A heatable high-pressure flow reactor of a new design was employed. Reaction 1 was studied over a buffer gas (He) pressure range 0.8−100 bar and a temperature range 498−769 K. Formyl radicals were prepared by pulsed photolysis of acetaldehyde and propionaldehyde (308 nm, XeCl excimer laser, 320 nm, doubled dye laser). In addition to formyl radicals monitored at 230 and 613.8 nm, methyl radicals were monitored via absorption at 216.5 nm. The initial concentrations of free radicals were varied between 7 × 1010 and 8 × 1013 molecules cm-3. The obtained second-order rate constant at 1 bar is k 1(He) = (0.8 ± 0.4) × 10-10 exp(−66.0 ± 3.4 kJ mol-1/RT) cm3 molecule-1 s-1 (498−769 K). The low-pressure data of this study were combined with those from a high-temperature shock tube study and the low-temperature data on the reverse reaction to yield k 1(He) = (0.60 ± 0.14) × 10-10 exp(−64.2 ± 1.4 kJ mol-1/RT) cm3 molecule-1 s-1 over an extended temperature range, 298−1229 K. The dissociation rate constants measured in this work are lower than previously reported by a factor of 2.2 at the highest temperature of our measurements and a factor of 3.5 at the low end. Our experimental data indicate a pressure dependence of the second-order rate constant for the dissociation of formyl radical (1), which is attributed to pressure falloff expected from the theory of isolated resonances.

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Section: Methodsmentioning

confidence: 73%

Section: Methodsmentioning

confidence: 99%

Unimolecular Dissociation of Formyl Radical, HCO → H + CO, Studied over 1−100 Bar Pressure Range

Krasnoperov¹,

Чесноков

Stark

et al. 2004

J. Phys. Chem. A

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show abstract

“…This expression shows that the reaction kinetics depends on: (i) the nature of monomers and porogens (through the rate‐constants of chain propagation k p and termination k t ), (ii) the nature of the photoinitiator (through the quantum yield for initiation Ф i and the molar extinction coefficient ε i at the wavelength of absorbed radiation) and its concentration C i , (iii) the irradiation conditions (through the wavelength of light source, the power received per unit area P (also named light intensity or irradiance), and the irradiation time t ). Light intensity is function of the power of light source and varies with the distance between light source and polymerization surface according to the inverse square law . The energy W reaching the surface per unit area is given by the following relationship: