Dissociative Electron Attachment inBr2at 296°K

Dissociative electron attachment frequencies have been determined for bromine in the presence of helium using microwave cavity techniques. Initial ionization was produced by a single light pulse from a hydrogen flash lamp. The value for the electron attachment coefficient $k$ determined from the attachment frequency data is $k=0.82\mathrm{}\times {10}^{-12}$ ${\mathrm{cm}}^3$ ${\sec }^{-1\mathrm{}}$ ±10% at 296 °K. The electron-ion ambipolar diffusion coefficient ($D_{a+}p$) for $\mathrm{Br}_2^{}{}_{}{}^{+}$ in helium was found to be 795 ${\mathrm{cm}}^2$ Torr ${\sec }^{-1\mathrm{}}$ ± 10% at 296 °K. The positive-ion-negative-ion ambipolar diffusion coefficient for this ion was found to be 380 ${\mathrm{cm}}^2$ Torr ${\sec }^{-1\mathrm{}}$ ± 10% at 296 °K under the conditions where the only significant negative ion present was ${\mathrm{Br}}^{-}$.