scholarly journals Photodissociation Mechanisms of Benzene Cluster Ions on the Excitation With hv = 0.5-3.0 eV

1995 ◽  
Vol 15 (2-4) ◽  
pp. 93-111 ◽  
Author(s):  
Kazuhiko Ohashi ◽  
Yasuhiro Nakai ◽  
Nobuyuki Nishi
Keyword(s):  
Photon Energy ◽  
Upper Bound ◽  
Bound State ◽  
Cluster Ions ◽  
Angular Distributions ◽  
Translational Energy ◽  
Neutral Cluster ◽  
Available Energy ◽  
Dissociative State

The photodissociation of mass-selected benzene cluster ions, (C6H6)n+(n=2−8), is studied to elucidate the dynamics of dissociation and the mechanism of fragmentation. For (C6H6)2+, the average translational energy and the angular distributions of the photofragments are measured as a function of photon energy (hv). The photoexcitation to an upper bound state with hv = 2.81 eV results in statistical energy disposal. Regardless of the excitation to a dissociative state with hv = 1.17-1.62 eV, only a small fraction (at most 10%) of the available energy is partitioned into the translation. For (C6H6)n+ with n = 5-8, the average number of neutral molecules ejected following photoexcitation increases linearly with increasing hv until (C6H6)2+ is reached as the product. The result suggests that the photofragmentation proceeds via the sequential evaporation of neutral monomers rather than the direct ejection of a neutral cluster.

scholarly journals The mathematical principles and design of the NAIS – a spectrometer for the measurement of cluster ion and nanometer aerosol size distributions

2013 ◽  
Vol 6 (4) ◽  
pp. 1061-1071 ◽  
Author(s):  
S. Mirme ◽  
A. Mirme
Keyword(s):  
Size Range ◽  
Aerosol Particles ◽  
Charged Particles ◽  
Cluster Ions ◽  
Size Distributions ◽  
Neutral Cluster ◽  
Design Data ◽  
Cluster Ion ◽  
Principles Of Design ◽  
Spectrum Deconvolution

Abstract. The paper describes the Neutral cluster and Air Ion Spectrometer (NAIS) – a multichannel aerosol instrument capable of measuring the distribution of ions (charged particles and cluster ions) of both polarities in the electric mobility range from 3.2 to 0.0013 cm2 V−1 s−1 and the distribution of aerosol particles in the size range from 2.0 to 40 nm. We introduce the principles of design, data processing and spectrum deconvolution of the instrument.

Angular distributions of the particles sputtered with Ar cluster ions

1998 ◽  
Vol 54 (1-3) ◽  
pp. 262-265 ◽  
Author(s):  
Noriaki Toyoda ◽  
Hiroaki Kitani ◽  
Norihisa Hagiwara ◽  
Takaaki Aoki ◽  
Jiro Matsuo ◽  
...  
Keyword(s):  
Cluster Ions ◽  
Angular Distributions

scholarly journals Photodissociation of Iso-Propoxy (I-C3H7O) Radical at 248 Nm

2020 ◽  
Author(s):  
Erin Sullivan ◽  
Steven Saric ◽  
Daniel Neumark
Keyword(s):  
Electronic State ◽  
Ground State ◽  
Branching Ratio ◽  
Ground Electronic State ◽  
Angular Distributions ◽  
Translational Energy ◽  
Energy And Angular Distributions ◽  
Three Body ◽  
State Dissociation

<p>Photodissociation of the <i>i</i>-C<sub>3</sub>H<sub>7</sub>O radical is investigated using fast beam photofragment translational spectroscopy. Neutral <i>i</i>-C<sub>3</sub>H<sub>7</sub>O radicals are produced through the photodetachment of a fast beam of <i>i</i>-C<sub>3</sub>H<sub>7</sub>O<sup>-</sup> anions and are subsequently dissociated using 248 nm (5.0 eV). The dominant product channels are CH<sub>3</sub> + CH<sub>3</sub>CHO and OH + C<sub>3</sub>H<sub>6</sub> with some contribution from H + C<sub>3</sub>H<sub>6</sub>O. CH<sub>3</sub> and H loss are attributed to dissociation on the ground electronic state of <i>i</i>-C<sub>3</sub>H<sub>7</sub>O, but in a nonstatistical manner because RRKM dissociation rates exceed the rate of energy randomization. Translational energy and angular distributions for OH loss are consistent with ground state dissociation, but the branching ratio for this channel is considerably higher than predicted from RRKM rate calculations. These results corroborate what has been observed previously in C<sub>2</sub>H<sub>5</sub>O dissociation at 5.2 eV that yields CH<sub>3</sub>, H, and OH loss. Additionally, <i>i</i>-C<sub>3</sub>H<sub>7</sub>O undergoes three-body fragmentation to CH<sub>3</sub> + CH<sub>3</sub> + HCO and CH<sub>3</sub> + CH<sub>4</sub> + CO. These three-body channels are attributed to dissociation of <i>i</i>-C<sub>3</sub>H<sub>7</sub>O to CH<sub>3</sub> + CH<sub>3</sub>CHO, followed by secondary dissociation of CH<sub>3</sub>CHO on its ground electronic state.</p>

scholarly journals Photodissociation of Iso-Propoxy (I-C3H7O) Radical at 248 Nm

2020 ◽  
Author(s):  
Erin Sullivan ◽  
Steven Saric ◽  
Daniel Neumark
Keyword(s):  
Electronic State ◽  
Ground State ◽  
Branching Ratio ◽  
Ground Electronic State ◽  
Angular Distributions ◽  
Translational Energy ◽  
Energy And Angular Distributions ◽  
Three Body ◽  
State Dissociation

<p>Photodissociation of the <i>i</i>-C<sub>3</sub>H<sub>7</sub>O radical is investigated using fast beam photofragment translational spectroscopy. Neutral <i>i</i>-C<sub>3</sub>H<sub>7</sub>O radicals are produced through the photodetachment of a fast beam of <i>i</i>-C<sub>3</sub>H<sub>7</sub>O<sup>-</sup> anions and are subsequently dissociated using 248 nm (5.0 eV). The dominant product channels are CH<sub>3</sub> + CH<sub>3</sub>CHO and OH + C<sub>3</sub>H<sub>6</sub> with some contribution from H + C<sub>3</sub>H<sub>6</sub>O. CH<sub>3</sub> and H loss are attributed to dissociation on the ground electronic state of <i>i</i>-C<sub>3</sub>H<sub>7</sub>O, but in a nonstatistical manner because RRKM dissociation rates exceed the rate of energy randomization. Translational energy and angular distributions for OH loss are consistent with ground state dissociation, but the branching ratio for this channel is considerably higher than predicted from RRKM rate calculations. These results corroborate what has been observed previously in C<sub>2</sub>H<sub>5</sub>O dissociation at 5.2 eV that yields CH<sub>3</sub>, H, and OH loss. Additionally, <i>i</i>-C<sub>3</sub>H<sub>7</sub>O undergoes three-body fragmentation to CH<sub>3</sub> + CH<sub>3</sub> + HCO and CH<sub>3</sub> + CH<sub>4</sub> + CO. These three-body channels are attributed to dissociation of <i>i</i>-C<sub>3</sub>H<sub>7</sub>O to CH<sub>3</sub> + CH<sub>3</sub>CHO, followed by secondary dissociation of CH<sub>3</sub>CHO on its ground electronic state.</p>

scholarly journals Photodissociation Dynamics of Arn+ Cluster Ions

1994 ◽  
Vol 14 (1-3) ◽  
pp. 15-29 ◽  
Author(s):  
Takashi Nagata
Keyword(s):  
Kinetic Energy ◽  
Energy Release ◽  
Simulation Analysis ◽  
Kinetic Energy Release ◽  
Cluster Ions ◽  
Angular Distributions ◽  
High Kinetic Energy ◽  
Spectral Profiles ◽  
Direct Dissociation ◽  
Energy And Angular Distributions

The time-of-flight (TOF) spectra of Ar+ and Ar fragments produced in the photodissociation of Arn+ (3 ≦ n ≧ 24) were measured at wavelength around 540 nm. The kinetic-energy and angular distributions of the neutral photofragments were obtained for n = 3, 9 and 24 by a simulation analysis of the measured TOF spectral profiles. The overall aspect of the photodissociation process of Arn+ is deduced from these distributions within the context of trimer ion core model; a linear Ar3+ core is solvated by neutral Ar atoms. For Arn+ with 4 ≦ n ≲ 14, direct dissociation of the Ar3+ chromophoric core gives rise to Ar+ and/or Ar fragments with a high kinetic energy release. For the larger Arn+ (n ≳ 14), the production of high-kinetic-energy fragments is suppressed; “evaporation” of the solvent Ar atoms is instead the dominant channel of photofragmentation.

Translational energy losses of LiF cluster ions

1994 ◽  
Vol 29 (11) ◽  
pp. 615-618 ◽  
Author(s):  
Károly Vékey ◽  
Krisztina Ludányi
Keyword(s):  
Cluster Ions ◽  
Energy Losses ◽  
Translational Energy

Translational energy and angular distributions of O() and O(j) fragments in the UV photodissociation of ozone

1998 ◽  
Vol 231 (2-3) ◽  
pp. 171-182 ◽  
Author(s):  
Kenshi Takahashi ◽  
Nori Taniguchi ◽  
Yutaka Matsumi ◽  
Masahiro Kawasaki
Keyword(s):  
Angular Distributions ◽  
Translational Energy ◽  
Energy And Angular Distributions

Ethylene Adsorption on Clean and Oxygen Covered Flat and Stepped Ag(001)

2003 ◽  
Vol 17 (13) ◽  
pp. 2497-2526 ◽  
Author(s):  
L. Vattuone ◽  
L. Savio ◽  
M. Rocca
Keyword(s):  
High Resolution ◽  
Gas Phase ◽  
Activation Barrier ◽  
Bound State ◽  
Translational Energy ◽  
X Rays ◽  
Vibrationally Excited ◽  
Supersonic Molecular Beam ◽  
Adsorption State ◽  
Ethylene Adsorption

In the present paper we review our findings on ethylene adsorption on clean and oxygen covered Ag(001) surfaces investigated by dosing the gas with a Supersonic Molecular Beam and analysing the adsorption state either by High Resolution Electron Energy Loss Spectroscopy or by High Resolution X Rays Photoemission Spectroscopy. The final adsorption state depends on the translational and on the internal energy of the gas-phase molecules and on the presence of defects. At low translational energy ethylene either physisorbs or very weakly chemisorbs at flat terrace sites. The physisorption probability is thereby hindered by rotational excitation. A more strongly bound, π bonded, state forms at higher translational energy, the activation barrier being related to the energy needed to form the relevant defect at which chemisorption takes place. A further even more strongly bound state forms only when dosing vibrationally excited molecules from the gas phase.

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