Evidence for a cage effect in the UV photolysis of HBr in ArHBr. Theoretical and experimental results

Segall, Jeffrey J.; Wen, Y.; Singer, Rachel; Wittig, C.; Garcı́a-Vela, A.; Gerber, R. B.

doi:10.1016/0009-2614(93)89037-i

Cited by 64 publications

(58 citation statements)

References 24 publications

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“…This hydrogen distribution would correspond with a monochromatic ͑CW or long-pulse͒ excitation of the system. 8,19 As was said in Sec. I, photolysis, of Ar-HCl may occur either via partial fragmentation ͑PF͒ into HϩAr-Cl ͑due to direct H dissociation͒, or total fragmentation ͑TF͒ into HϩArϩCl ͑due both to direct and indirect hydrogen photodissociation͒.…”

Section: Theoretical Treatmentmentioning

confidence: 80%

“…For excitation to an energy E we can explained by the authors, 8 the experiment is not completely size selected, and Ar n -HBr clusters with nϾ1 may contribute to some extent to the signal of Fig. 4.…”

Section: F Classical Collisional Modelmentioning

confidence: 99%

“…8,9 The theoretical distribution corresponding with this observable is P(⑀ k H ,E). Figure 6 shows the P(⑀ k H ,E) distributions associated with six different total energies, along the range covered by the Ar-HCl absorption spectrum.…”

Section: E Energy-resolved Kinetic-energy Distributions Of the Hydromentioning

confidence: 99%

“…Most of the theoretical [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] and experimental 8,19 research effort on this line has been addressed to the smallest size of this type of clusters, Rg-HX ͑Rgϭrare gas, Xϭhalogen͒. Some simulations were carried out for larger systems like Xe n -HI (nϭ1 -12), 1 Ar n -HF (nϭ1 -14,54), 12 and Ar n -HCl (nϭ1,2,12,54).…”

Section: Introductionmentioning

confidence: 99%

“…Such a distribution is the equivalent one in the energy domain to the H fragment time-of-flight ͑TOF͒ spectrum measured in an energyresolved experiment. 8,19 The paper is organized as follows. In Sec.…”

Section: Introductionmentioning

confidence: 99%

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Photodissociation of Ar–HCl: An energy-resolved study of the dynamics of total fragmentation into H+Ar+Cl

Juanes‐Marcos

Garcı́a-Vela

1999

The Journal of Chemical Physics

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UV photolysis of Ar-HCl is simulated by means of an exact wave packet treatment in three dimensions. The focus of the work is on the mechanism of indirect dissociation of the hydrogen atom, which leads to total fragmentation of Ar-HCl into H, Ar, and Cl. The results predict for this photodissociation path a probability of about 13% of the photolysis process. The remaining probability would be associated with direct photodissociation of the H fragment. Kinetic-energy distributions of the hydrogen fragments produced by indirect photodissociation are calculated for different excitation energies of Ar-HCl. The distributions reflect a pronounced structure of peaks associated with broad and overlapping resonances of the system. The resonance structure is present in the whole energy range covered by the absorption spectrum. Hydrogen atoms initially populating the resonances can dissociate from the cluster extensively cooled down, after several collisions with Ar and Cl. A mechanism is suggested for the fragmentation process due to indirect photodissociation, which involves successive jumps of the hydrogen to lower-energy resonances, induced by the collisions. A classical collisional model is proposed to rationalize qualitatively the fragmentation dynamics.

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Section: Theoretical Treatmentmentioning

confidence: 80%

Section: F Classical Collisional Modelmentioning

confidence: 99%

Section: E Energy-resolved Kinetic-energy Distributions Of the Hydromentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Photodissociation of Ar–HCl: An energy-resolved study of the dynamics of total fragmentation into H+Ar+Cl

Juanes‐Marcos

Garcı́a-Vela

1999

The Journal of Chemical Physics

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Dynamics of Photoinduced Reactions in van der Waals and in Hydrogen‐Bonded Clusters

Gerber¹,

McCoy²,

Garcı́a-Vela³

1994

Femtosecond Chemistry

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Photodissociation and size analysis of (HBr)_n clusters

Baumfalk¹,

Buck²,

Frischkorn³

et al. 1997

Ber Bunsenges Phys Chem

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Hydrogen bromide clusters that are generated in an adiabatic expansion with Ar are size-selected by scattering from a He or a Ne beam and a subsequent separation by a velocity selector. The complete fragmentation pattern for electron impact ionization of clusters n = 3,5,7,10, and 15 is obtained for electron energies of 70 eV. Up to cluster sizes of n = 15 strong fragmentation is observed. Based on these results the cluster sizes are measured as a function of different source conditions. For the same experimental conditions the (HBr), clusters are photoionized at 243.1 nm. A time-of-flight mass spectrometer with low extraction fields is used to obtain the translational energy distributions of hydrogen atoms. Several distinct features are observed which sensitively depend on the cluster size. At small cluster sizes a tail appears towards lower energies in the fast hydrogen kinetic energy distribution which is caused by few collisions with the cluster molecules. Peaks at higher energies are attributed to internally excited HBr molecules which gain their energy in collisions with photofragmented H atoms. Small clusters exhibit pure rotational excitation with averaged J = 7, while the larger ones show vibrational excitations to u = 1 with J = 8 and u = 2. Finally, we observe a narrow H component peaking near zero velocity and exhibiting an isotropic angular distribution. This effect appears only at larger cluster sizes and is attributed to a complete caging of the photofragments.

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Evidence for a cage effect in the UV photolysis of HBr in ArHBr. Theoretical and experimental results

Cited by 64 publications

References 24 publications

Photodissociation of Ar–HCl: An energy-resolved study of the dynamics of total fragmentation into H+Ar+Cl

Photodissociation of Ar–HCl: An energy-resolved study of the dynamics of total fragmentation into H+Ar+Cl

Dynamics of Photoinduced Reactions in van der Waals and in Hydrogen‐Bonded Clusters

Photodissociation and size analysis of (HBr)_n clusters

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Evidence for a cage effect in the UV photolysis of HBr in ArHBr. Theoretical and experimental results

Cited by 64 publications

References 24 publications

Photodissociation of Ar–HCl: An energy-resolved study of the dynamics of total fragmentation into H+Ar+Cl

Photodissociation of Ar–HCl: An energy-resolved study of the dynamics of total fragmentation into H+Ar+Cl

Dynamics of Photoinduced Reactions in van der Waals and in Hydrogen‐Bonded Clusters

Photodissociation and size analysis of (HBr)n clusters

Contact Info

Product

Resources

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Photodissociation and size analysis of (HBr)_n clusters