Two-photon VUV laser-induced fluorescence detection of I★(2P12) and I(2P12) from alkyl iodide photodissociation at 248 nm

Godwin, F.G.; Gorry, P.A.; Hughes, Patrick M.; Raybone, D.; Watkinson, T.M.; Whitehead, J. Christopher

doi:10.1016/0009-2614(87)87237-8

Cited by 64 publications

(34 citation statements)

References 27 publications

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“…At these wavelengths no significant contribution is made by the 3~1 state, as pointed out by Gedanken and Rowe (1). The energy disposal at these two wavelengths inay be best described by a simple classical inodel suggested by Godwin et al (10). In their model the I:$ quantum yield is described by the probability of staying on the initial ",, state as,…”

Section: Discussionmentioning

confidence: 99%

“…Photofragmentation of CH31 at 248 nm was studied by Barry and Gorry (9); they observed the v2 vibrational distribution to peak at v = 2 for the I* channel, and to extend up to v = 8 for the I channel. Using the TPLIF technique, Godwin et al (10) measured the quantum yield for production of I and I* for a series of alkyl iodides at 248 nm. They observed that the 12: yield or the dynamics of I* production varies with the alkyl radical size, substitutions on a-and P-carbon atoms, and structure.…”

Section: Introductionmentioning

confidence: 99%

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Dynamics of I*(²P_1/2) production in the ultraviolet photodissociation of alkyl iodides

Uma¹,

Das²

1994

Can. J. Chem.

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The relative quantum yields, +*, for the production of I * (~P~/~) at 266,280, and -305 nm are reported for a series of primary alkyl iodides using the technique of two-photon laser-induced fluorescence for the detection of I (~P~/~) and I * (~P , /~) atoms. Results are analyzed by invoking the impulsive energy disposal model, which summarizes the dynamics of dissociation as a single parameter. Comparison of our data with those calculated by a more sophisticated time-dependent quantum mechanical model is also made. Near the red edge of the alkyl iodideA band, absorption contribution from the 3~1 state is important and the dynamics near the 3~o -1~1 curve-crossing region seem to be influenced by the kinematics of the dissociation process.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dynamics of I*(²P_1/2) production in the ultraviolet photodissociation of alkyl iodides

Uma¹,

Das²

1994

Can. J. Chem.

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“…In the 200-320 nm region, the excitation of C 2 H 5 I is assigned to the * n σ → transition, giving photodissociation. The photodissociation channel ratio has been studied with different methods, such as the laser-induced fluorescence (LIF) [18,19] , PTS [7,12] , etc. I*( 2 P 1/2 )/I( 2 P 3/2 ) is controlled by the excitation probability to the 3 Q 0 , 3 Q 1 , 1 Q 1 excited states and the curve crossing between 3 Q 0 and 1 Q 1 during the dissociation process [12] .…”

mentioning

confidence: 99%

“…The photodissociation of ethyl iodide (C 2 H 5 I) has been widely studied [12][13][14][15][16][17][18][19] . The absorption cross-section of C 2 H 5 I was measured in the range of 235-400 nm [16] .…”

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confidence: 99%

High-resolution photofragment translational spectroscopy for the UV photodissociation of C2H5I

Huang

et al. 2007

SCI CHINA SER B

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The photodissociation of ethyl iodide at 279.71, 281.73, 304.02 and 304.67 nm has been studied on our new mini-photofragment translational spectrometer with a total flight path of only 5 cm. Some vibrational peaks are firstly resolved in the TOF spectra of I*( 2 P 1/2 ) and I( 2 P 3/2 ) channels. These vibrational peaks are assigned to the excitation states (ν 2 = 0, 1, 2,…) of the umbrella mode (ν 2 , 540 cm −1 ) of the photofragment C 2 H 5 , and the distribution of the vibrational states is obtained. The dissociation energy has been determined to be D 0 (C-I)=2.314 ± 0.03 eV. The energy partitioning of the available energy (E avl =E T +E int =E T +E V,R ) calculated from our experimental data / int avl E E = 22.1% at 281.73 nm, 22.4% at 304.02 nm for the I* channel, and / int avl E E = 25.2% at 279.71 nm, 25.9% at 304.67 nm for the I channel, seem to be more reliable. photofragment translational spectroscopy, C 2 H 5 I, photodissociation, vibrational state distribution, energy partitioning，dissociation energyFor the photodissociation of molecules, photofragment translational spectroscopy offers a way to study the dynamics of photodissociation in a collision-free regime [1] . Analysis of the velocity distribution and the angular distribution of the photofragments can give information of the potential energy surfaces, the energy partitioning, the vibrational state distribution of the photofragments, the dissociation energy, the life time of the excitation state and the curve-crossing. The original photofragment translational spectrometer (PTS) [2,3] was with the structure that the molecular beam, the laser, and the detection axis were perpendicular to each other. The improved PTS, with the molecular beam rotatable, was called the "Rotating Source Machine" at Yuan Lee's Lab in U.C. Berkeley [4] . At the same time, similar experimental set-ups were built in the University of Manchester [5] and in our laboratory [6,7] . This kind of experimental apparatus is still used in many laboratories. Some high resolution experimental results have been obtained [8,9] , but the apparatus is very complicated and in need of ultra-high vacuum up to 10 −8 Pa. At present, the ion imaging apparatus, originally designed by Chandler and Houston [10] , and improved by Eppink and Parker [11] , is used more often. From the ion image, the angular distribution of the photofragments can be obtained simultaneously with the high-resolution velocity distribution, but high-grade uniform Micro Channel Plates (MCP) and CCD camera are required. We have built a simple and small photofragment translational spectrometer of only 5 cm total flight path and used a simple MCP as the detector. However, the resolution of this PTS is high enough to resolve some vibrational states of the photofragments.Alkyl halides have been concerned to the atmospheric chemistry due to their role in ozone depletion. The photodissociation of ethyl iodide (C 2 H 5 I) has been widely studied [12][13][14][15][16][17][18][19] . The absorption cross-section of C 2 H 5 I was meas...

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“…C 2 H 5 I在 235 ~ 400 nm范围内的吸收曲线曾被测量 [16] , 其中在 200 ~ 320 nm范围内, C 2 H 5 I的激发对应于n→σ *跃迁, 并导致光解. 众多科研人员采用不同的方法研究了C 2 H 5 I的光解通道分支比 I*( 2 P 1/2 )/I( 2 P 3/2 ), 如激光诱导荧光 (LIF) [18,19] 、光解碎片平动能谱 [7,12] 等 . 分支比 [12] .…”

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高分辨光解碎片平动能谱研究C<sub>2</sub>H<sub>5</sub>I的紫外光解

毕渭滨¹,

徐西玲²,

黄贱苟³

et al. 2007

SSB

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Two-photon VUV laser-induced fluorescence detection of I★(2P12) and I(2P12) from alkyl iodide photodissociation at 248 nm

Cited by 64 publications

References 27 publications

Dynamics of I*(²P_1/2) production in the ultraviolet photodissociation of alkyl iodides

Dynamics of I*(²P_1/2) production in the ultraviolet photodissociation of alkyl iodides

High-resolution photofragment translational spectroscopy for the UV photodissociation of C2H5I

高分辨光解碎片平动能谱研究C<sub>2</sub>H<sub>5</sub>I的紫外光解

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Two-photon VUV laser-induced fluorescence detection of I★(2P12) and I(2P12) from alkyl iodide photodissociation at 248 nm

Cited by 64 publications

References 27 publications

Dynamics of I*(2P1/2) production in the ultraviolet photodissociation of alkyl iodides

Dynamics of I*(2P1/2) production in the ultraviolet photodissociation of alkyl iodides

High-resolution photofragment translational spectroscopy for the UV photodissociation of C2H5I

高分辨光解碎片平动能谱研究C&lt;sub&gt;2&lt;/sub&gt;H&lt;sub&gt;5&lt;/sub&gt;I的紫外光解

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Dynamics of I*(²P_1/2) production in the ultraviolet photodissociation of alkyl iodides

Dynamics of I*(²P_1/2) production in the ultraviolet photodissociation of alkyl iodides

高分辨光解碎片平动能谱研究C<sub>2</sub>H<sub>5</sub>I的紫外光解