Photodissociation dynamics of 1,2- and 2,2-dibromopropane at 234 and 265nm by velocity map ion imaging technique고분해 이온 영상장치를 이용한 1,2- 와 2,2-dibromopropane의 234, 265nm 에서의 광분해 동역학 연구

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The photodissociation dynamics of 1,2- and 2,2-dibromopropane at 234 and 265 nm have been investigated using the velocity-map ion imaging technique. The experimental data and theoretical calculations provide information on the translational energy distributions of the photoproducts $(Br and Br^*)$. 1,2-dibromopropane $(CH_3CHBrCH_2Br)$ At both wavelengths, structured images of Br have been obtained for the spin-orbit ground state $Br(^2P_{3/2})$, while no structures was observed on the images of the spin-orbit excited state $Br^*(^2P_{1/2})$. The obtained translational energy distributions of Br have been reproduced by at least three Gaussian functions and those of $Br^*$ show a single Gaussian distribution. The secondary dissociation of Br atom from the bromopropyl radical, following the first C-Br bond rupture of 1,2-dibromopropane has been considered to explain the observed results, represented by $CH_3CHBrCH_2Br → (1) C_3H_6Br + Br^*(^2P_{1/2})^{1st} → $C_3H_6$ + Br(^2P_{3/2})^{2nd} + Br^*(^2P_{1/2})^{1st}$ and (2) $C_3H_6Br + Br(^2P_{3/2})^{1st} → C_3H_6 + Br(^2P_{3/2})^{2nd} + Br(^2P_{3/2})^{1st$. The dissociation energy of the C-Br bond for each process is obtained by ab initio calculation and is given to be $D_0(Br-C_3H_6Br)=59.02$ and $D_0(Br-C_3H_6)=10.98$ kcal/mol. The recoil anisotropy parameter (β) is determined to be 0.53 and 1.26 for $Br(^2P_{3/2})^{1st}$ and $Br^*(^2P_{1/2})^{1st}$, respectively, at 234 nm, while the values are 0.49 and 1.73, respectively, at the longer wavelength of 265 nm. $Br(^2P_{3/2})^{2nd}$ produced by the secondary dissociations gives the value of $\beta$ =0.87 as high as $Br(^2P_{3/2})^{1st}$ implying that the anisotropic angular distributions are originated from the vector sum of the isotropic velocities of $Br^{2nd}$ and the velocity of the center of mass determined by $Br^{2nd}$ and propene, $C_3H_6$, product. 2,2-dbromopropane $(CH_3CBr_2CH_3)$ At both wavelengths, the experimental data are well fitted by three...
Advisors
Kim, Sang-Kyuresearcher김상규researcher
Description
한국과학기술원 : 화학과,
Publisher
한국과학기술원
Issue Date
2007
Identifier
265089/325007  / 020053341
Language
eng
Description

학위논문(석사) - 한국과학기술원 : 화학과, 2007.2, [ ix, 66 p. ]

Keywords

2,2-dibromopropane; 1,2-dibromopropane; photodissociation; dibromopropane; 고분해 이온 영상장치; 2,2-dibromopropane; 1,2-dibromopropane; 광분해; velocity map ion imaging

URI
http://hdl.handle.net/10203/32057
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=265089&flag=dissertation
Appears in Collection
CH-Theses_Master(석사논문)
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