Photodissociation dynamics of alkyl halide with two chromophores using photofragment imaging technique

Abstract

Photodissociation of $Br_2$ at 234 and 265 nm : New products of $Br(5s ^4P_J)$ via a two-photon dissociation The photodissociation of $Br_2$ has been investigated at 234 and 265 nm utilizing a two dimensional photofragment ion imaging system. Atomic bromine fragments monitored in this study were produced via a direct two-photon dissociation of $Br_2$ as well as a one-photon dissociation. The fragments via the two-photon dissociation were assigned to $Br(5s ^4P_J$ : J = 5/2, 3/2, 1/2) by analyzing their photoelectron images. The speed and angular distributions of the fragments via the one-photon dissociation revealed a unique photoexcitation to the 1441 $^3∑_u^+(1_u)$ state and the dissociation into $Br(4p ^2P_{3/2}$) + $Br(4p ^2P_{1/2}$) at 234 nm while both $Br(4p ^2P_{3/2}$) + $Br(4p ^2P_{1/2}$) and $Br(4p ^2P_{3/2}$)+$Br(4p ^2P_{3/2}$) dissociation channels were observed with the relative quantum yields $φ(Br(4p ^2P_{3/2}$)+$Br(4p ^2P_{1/2}$)) = 0.96 and $φ(Br(4p ^2P_{3/2}$)+$Br(4p ^2P_{3/2}$)) = 0.04, respectively, at 265 nm. The role of $^3Π_{0^+}$ in the photodissociation of BrCl at 235 nm The photodissociation of BrCl has been investigated at 235 nm using a two dimensional photofragment ion imaging technique. Atomic chlorine fragments monitored in this study were produced via direct dissociation of BrCl. Three dissociation channels $(Br(^2P_{1/2}$)+$Cl(^2P_{3/2}$), $Br(^2P_{3/2}$)+$Cl(^2P_{1/2}$) and $Br(^2P_{3/2}$)+$Cl(^2P_{3/2}$)) were observed and their angular distributions were represented by anisotropy parameters, β=1.98±0.05, -1.04±0.05, and 1.88±0.05, respectively. The quantum yield for each channel observed in this work were $φ(Br(^2P_{1/2}$)+Cl(^2P_{3/2}))=0.58±pm0.05$, $φ(Br(^2P_{3/2})+ Cl(^2P_{1/2}$))=0.16±0.05$, and $φ(Br(^2P_{3/2})+Cl(^2P_{3/2}))=0.26±0.05$. These results show that the 2341 $^3φ_{0^+}$ state plays a key role in the dissociation dynamics after absorbing a photon. Photodissociation of $CBrCl_3$ at 234 and 265 nm : Evidence of...