• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2661-2664
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• 2009

Photodissociation of nitrous oxide near 203 nm has been studied by a combination of high resolution slice ion imaging technique and (2+1) resonance-enhanced multiphoton ionization (REMPI) spectroscopy of $N_2(X^1{{\Sigma}_g}^+)$ via the (a″$^1{{\Sigma}_g}^+$) state. We have measured the recoil velocity and angular distributions of $N_2$ fragments by ion images of the state-resolved photofragments. The $N_2$ fragments were highly rotationally excited and the NN-O bond dissociation energy was determined to be 3.635 eV. Also, we investigated the photofragment images from the photodissociation of $N_2O$ clusters with various stagnation pressures.

• Bulletin of the Korean Chemical Society
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• v.13 no.2
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• pp.162-165
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• 1992

The fine structure branching ratio and Doppler profiles of photofragment Cl ($^{2}P_{j}$) atoms from photodissociation of CINO around 236 nm in the A band have been measured by the two photon resonance enhanced multiphoton ionization technique. The measured branching ratio, $Cl^{\ast} (^{2}P_{1/2})/Cl (^{2}P_{3/2})$ is $0.18{\pm}0.02$. The Doppler profile of Cl is well reproduced assuming that one of the two components in the photofragment translational spectra reported by Haas, Felder, and Huber [Chem. Phys. Lett., 180, 293 (1990)] should correspond to Cl and that an anisotropy parameter $\beta$ for the angular distribution is 0.45. The results suggest that CINO dissociation in the A band should consist of at least two non-crossing electronic states which correlate to the formation of $Cl^* and Cl, respectively.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.659-663
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• 2011

The photodissociation dynamics of bromobenzene near 234 nm has been investigated using a two-dimensional photofragment ion-imaging technique coupled with a state-selective [2+1] resonance-enhanced multiphoton ionization (REMPI) scheme. The nascent Br atoms are produced by the primary C-Br bond dissociation, which leads to the formation of $C_6H_5$ ($\tilde{X}$) and Br($^2P_j$, j = 1/2, 3/2). The observed translational energy distributions have been fitted by a single Boltzmann function and two Gaussian functions. Trimodal translational energy distributions of Br($^2P_j$) have been assigned to the direct/indirect dissociation mechanisms originating from the initially excited $^3({\pi},{\pi}^*)$ state. The assignments have been confirmed by the recoil anisotropy and distribution width corresponding to the individual components.

• Bulletin of the Korean Chemical Society
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• v.33 no.1
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• pp.143-148
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• 2012

The photodissociation dynamics of cyclopropyl bromide ($C_3H_5Br$) and cyclobutyl bromide ($C_4H_7Br$) at 234 nm was investigated. A two-dimensional photofragment ion-imaging technique coupled with a [2+1] resonanceenhanced multiphoton ionization scheme was utilized to obtain speed and angular distributions of the nascent $Br(^2P_{3/2})$ and $Br^*(^2P_{1/2})$ atoms. The recoil anisotropies for the Br and $Br^*$ channels were measured to be ${\beta}_{Br}=0.92{\pm}0.03$ and ${\beta}_{Br^*}=1.52{\pm}0.04$ for $C_3H_5Br$ and ${\beta}_{Br}=1.10{\pm}0.03$ and ${\beta}_{Br^*}=1.49{\pm}0.05$ for $C_4H_7Br$. The relative quantum yield for Br was found to be ${\Phi}_{Br}=0.13{\pm}0.03$ and for $C_3H_5Br$ and $C_4H_7Br$, respectively. The soft radical limit of the impulsive model adequately modeled the related energy partitioning. The nonadiabatic transition probability from the 3A' and 4A' potential energy surfaces was estimated and discussed.

• Bulletin of the Korean Chemical Society
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• v.30 no.12
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• pp.2962-2968
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• 2009

The photodissociation dynamics of 1,2-bromochloroethane ($C_2H_4BrCl$) was investigated near 234 nm. A two-dimensional photofragment ion-imaging technique coupled with a [2+1] resonance-enhanced multiphoton ionization scheme was utilized to obtain speed and angular distributions of the nascent Br($^2P_{3/2}$) and Br${\ast}($^2P_{1/2}$) atoms. The total translational energy distributions for the Br and Br${\ast}$ channels were well characterized by Gaussian functions with average translational energies of 100 and 84 kJ/mol, respectively. The recoil anisotropies for the Br and Br${\ast}$ channels were measured to be ${\beta}$ = 0.49 ${\pm}$ 0.05 for Br and 1.55 ${\pm}$ 0.05 for Br${\ast}$. The relative quantum yield for Br${\ast}$ was found to be ${\Phi}_{Br{\ast}}$ = 0.33 ${\pm}$ 0.03. The probability of nonadiabatic transition between A' states was estimated to be 0.46. The relevant nonadiabatic dynamics is discussed in terms of interaction between potential energy surfaces in Cs symmetry.