Vibrational and total energy dependence of the reaction rate of Na with CO2 laser-excited SF6

Abstract

The rate of reaction between sodium and sulfur hexafluoride has been studied as a function of the vibrational energy and total thermal energy of the SF6 in the temperature range 380–440 °K. Vibrational energy was increased by absorption of radiation from a pulsed CO2 laser, and total energy was increased by heating the reaction system. The reaction rate was determined as a function of energy in the time period after the laser pulse when the vibrational energy was equilibrated within the vibrational modes but there was no appreciable relaxation to translational energy. It has been determined that the reaction rate increases with the addition of vibrational energy but is essentially unaffected by additional translational energy. The results are in accordance with a statistical reaction rate theory which suggests that additional translational energy has no further effect in promoting a very exothermic polyatomic reaction.

Multiple Chemiluminescent Channels in the Reaction Mn + SF6 → MnF + SF5

“…As indicated in the Introduction, there has been some dispute about the SF 5 -F bond energy, but in the absence of a full report from the authors of ref 29, we feel obliged to accept the former value 14,15 for D 0 (SF 5 -F), 391 ( 15 kJ mol -1 . As far as E v,r -(SF 6 ) is concerned, a significant role might be expected by comparison with the ground-state K + SF 6 and Na + SF 6 reactions: 11,12 as the activation energy increases from ∼2.4 to ∼13.8 kJ mol -1 , with concomitant decrease in exoergicity, the number of SF 6 vibrational modes involved seems to increase from 1 to ∼10. However, for that to apply in the present case, we would expect the rise part of each excitation function to follow, initially, the microcanonical transition state theory expression 51…”

“…On the other hand, angular scattering measurements on Li + SF 6 , find a short-lived complex, and here electric resonance data indicate that dynamics, rather than statistics, still dominate the energy partitioning. “Diffusion cloud” experiments at ∼380 K, using infrared laser excitation of SF 6 ( v ), , find that only one S−F stretching vibrational mode is important for K + SF 6 , i . e ., SF 6 behaves like a diatomic; however, ∼10 modes appear to be involved for the Na reaction, which has a higher activation energy.…”

Differential cross sections for reactive scattering of sodium from sulfur hexafluoride

“…This lead us to the determination of the critical impact parameter bc = 3.9 ± 0.4 A. By using the expression for the total reactive cross section cr = 2*j¡P(b)báb (4) we obtain <rr = 46 ± 3 A2.…”

Energy dependence of the reaction of laser-excited sulfur hexafluoride with potassium vapor

“…By studying the vibrational energy dependence of the react rate at various temperatures, we have compared the importance of vibrational and translational energy in promoting the reaction. 2 In the present work we report on the reaction K + SF6 studied by essentially the same diffusion cloud technique employed in the previous work. The temperature dependence of the reaction suggests that vibrational energy is significant in promoting the reaction, while additional translational energy has little, if any, effect.…”