Estudio cinético de reacciones fotoquímicas y térmicas en las que intervienen átomos de flúor y radicales FCO

De las investigaciones sistemáticas realizadas por el Prof. Schumacher y colaboradores, sobre la cinética de las reacciones del flúor y del monóxido de flúor, se conoce el mecanismo de la descomposición térmica y fotoquímica de este último, así como el comportamiento cinético en reacciones fotoquímicas y térmicas de ambos reactivos con gran número de compuestos. En particular, se ha estudiado la reacción térmica entre F2O y CO, la reacción fotoquímica a 366 nm entre los mismos reactivos y la reacción térmica entre F2, CO y O2. En los mecanismos de estas reacciones se postula la intervención de los radicales OF, FCO, FOCO, FCO, 02 y átomos de F.Material digitalizado en SEDICI gracias a la colaboración de la Biblioteca de la Facultad de Ciencias Exactas (UNLP).Facultad de Ciencias Exacta

Theoretical Study of the Absorption Spectrum and the Thermochemistry of the CF3OSO3 Radical

The UV-visible absorption spectrum of the recently reported CF3OSO3 radical has been studied by using the time-dependent generalization of the density functional theory (TDDFT). For this a set of eleven hybrid functionals combined with the 6-311+G(3df) basis set were employed. The main features of the three experimental absorption bands of CF3OSO3 recorded over the 220-530 nm range are well reproduced by the calculations. A dissociation enthalpy for the CF3O-SO3 bond of 19.1 kcal mol-1 is predicted at the BAC-G3MP2//B3LYP/6-311+G(3df) level of theory.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Theoretical Study of the Absorption Spectrum and the Thermochemistry of the CF3OSO3 Radical

The UV-visible absorption spectrum of the recently reported CF3OSO3 radical has been studied by using the time-dependent generalization of the density functional theory (TDDFT). For this a set of eleven hybrid functionals combined with the 6-311+G(3df) basis set were employed. The main features of the three experimental absorption bands of CF3OSO3 recorded over the 220-530 nm range are well reproduced by the calculations. A dissociation enthalpy for the CF3O-SO3 bond of 19.1 kcal mol-1 is predicted at the BAC-G3MP2//B3LYP/6-311+G(3df) level of theory.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Theoretical study of the electronic spectrum of disulfur monoxide

The near ultraviolet-visible absorption spectrum of disulfur monoxide (S2O) has been theoretically studied by using the time-dependent density functional theory (TD-DFT) and the equation of motion coupled-cluster singles and doubles approach (EOM-CCSD) combined with the AUG-cc-PVQZ basis set. From this, analytical expressions for the absorption coefficient over the 250 - 340 nm range are reported for the first time. The computed molecular structure and the vibrational frequencies for the ground and third electronically excited state S2O (C1A′), responsible of the observed spectrum, are compared with available data.Facultad de Ciencias ExactasInstituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Theoretical Study of the Absorption Spectrum and the Thermochemistry of the CF3OSO3 Radical

The UV-visible absorption spectrum of the recently reported CF3OSO3 radical has been studied by using the time-dependent generalization of the density functional theory (TDDFT). For this a set of eleven hybrid functionals combined with the 6-311+G(3df) basis set were employed. The main features of the three experimental absorption bands of CF3OSO3 recorded over the 220-530 nm range are well reproduced by the calculations. A dissociation enthalpy for the CF3O-SO3 bond of 19.1 kcal mol-1 is predicted at the BAC-G3MP2//B3LYP/6-311+G(3df) level of theory.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Theoretical study of the electronic spectrum of disulfur monoxide

The near ultraviolet-visible absorption spectrum of disulfur monoxide (S2O) has been theoretically studied by using the time-dependent density functional theory (TD-DFT) and the equation of motion coupled-cluster singles and doubles approach (EOM-CCSD) combined with the AUG-cc-PVQZ basis set. From this, analytical expressions for the absorption coefficient over the 250 - 340 nm range are reported for the first time. The computed molecular structure and the vibrational frequencies for the ground and third electronically excited state S2O (C1A′), responsible of the observed spectrum, are compared with available data.Facultad de Ciencias ExactasInstituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Theoretical Study of the Electronic Spectrum of Disulfur Monoxide

The near ultraviolet-visible absorption spectrum of disulfur monoxide (S2O) has been theoreticallystudied by using the time-dependent density functional theory (TD-DFT) and the equation of motion coupled-cluster singles and doubles approach (EOM-CCSD) combined with the AUG-cc-PVQZ basis set. From this, analytical expressions for the absorption coefficient over the 250 ? 340 nm range are reported for the first time. The computed molecular structure and the vibrational frequencies for the ground and third electronically excited state S2O (C 1A′), responsible of the observed spectrum, are compared with available dataFil: Cobos, Carlos Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina. Universidad Nacional de La Plata; ArgentinaFil: Croce, Adela Ester. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina. Universidad Nacional de La Plata; Argentin

Quantum-chemical and kinetic study of the reactions of the ClSO2 radical with H, O, Cl, S, SCl and ClSO2 in the atmosphere of Venus

Rate constants for the reactions between the ClSO2 radical and H, O, Cl, S, SCl and ClSO2 were studied over the 150–700 K temperature range employing the statistical adiabatic channel model/classical trajectory approach and the canonical transition state theory on potential energy surfaces based on G4//B3LYP/6-311++G(3df,3pd) calculations. For these processes the following rate constants (in cm3 molecule−1 s−1) are predicted: 2.71 x 10- 11(T/250)0.47 (ClSO2 + H → HCl + SO2); 7.69 x 10- 11(T/250)0.093 (ClSO2 + O → Cl + SO3); 1.44 x 10- 11(T/250)0.47 (ClSO2 + Cl → Cl2SO2); 6.73 x 10- 11(T/250)0.18 (ClSO2 + S → SCl + SO2); 9.38 x 10- 13(T/250)0.75 (ClSO2 + SCl → ClS(O2)SCl); 2.64 x 10- 14(T/250)0.61 (2 ClSO2 → (O2)ClSSCl(O2)). These data are in marked contrast with those normally used for the modeling of the lower and middle atmosphere of Venus. Therefore, in the absence of experimental and theoretical investigations, the above rate constants are proposed for these studies.Fil: Croce, Adela Ester. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Cobos, Carlos Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentin

Theoretical Kinetics Study of the Reactions Forming the ClCO Radical Cycle in the Middle Atmosphere of Venus

A quantum-chemistry and kinetics study of key chemical reactions involved in the ClCO radical cycle of the Venus atmosphere: Cl + CO + M → ClCO + M (1); ClCO + O2 + M → ClC(O)OO + M (2) and ClC(O)OO + Cl → CO2 + ClO + Cl (3) (M = CO2), has been performed at 150-300 K. Unimolecular reaction rate theories on potential energy features derived at the G4//B3LYP/6-311+G(3df) ab initio composite level were employed. Limiting low pressure rate coefficients calculated for Reaction (1) are in good agreement with recommended experimental values. The present results validate rate coefficient values measured for Reaction (2) over relevant strato-mesosphere Venusian conditions. Rate coefficients calculated by the SACM/CT for Reaction (3) are given by k3 = 2.5 × 10-11 (T/300)0.5 cm3 molecule-1 s-1. In the absence of experimental data, these values provide the first reliable prediction for k3.Fil: Cobos, Carlos Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Croce, Adela Ester. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentin

A theoretical study of the thermal stability of the FS(O<SUB>2</SUB>)OSO<SUB>2</SUB> radical and the recombination kinetics with the FSO<SUB>3</SUB> radical

The kinetics of the thermal reaction of FS(O2)OO(O2)SF with SO2 have been theoretically studied. Experimental investigations performed at 293–323 K indicate that the FSO3 radical, in equilibrium with the peroxide FS(O2)OO(O2)SF ¢ 2 FSO3 (1, -1), initially attacks the SO2 forming the FS(O2)OSO2 radical which afterwards may dissociate back, FSO3 + SO2 ¢FS(O2)OSO2 (2, -2), or recombinewith FSO3 generating the final product, FSO3 + FS(O2)OSO2? (FS(O2)O)2SO2 (3). Several DFT formulations and composite ab initio models were employed to characterize FS(O2)OSO2 molecular properties and to determine relevant potential energy surfaces features of reactions (2), (-2) and (3). Transition state theory calculations lead to the high pressure rate coefficients k1;2 ¼ 9:1 10 14 expð 5:2 kcal mol 1 = RTÞ cm3 molecule 1 s 1 and k1; 2 ¼ 4:9 1015 expð 13:9 kcal mol 1 =RTÞ s 1 while statistical adiabatic channel model (SACM/CT) calculations predict for the barrierless reaction (3) the expression k1;3 ¼ 2:9 10 11ðT=300Þ0:4 cm3 molecule 1 s 1. The experimental phenomenological rate coefficients are very well reproduced by these rate coefficients.Facultad de Ciencias Exacta