Collision-induced absorption in the far infrared region in ethylene – rare gas mixtures

Dagg, I. R.; Read, L. A. A.; Smith, W. L.

doi:10.1139/p82-193

Cited by 16 publications

(8 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These compare favorably with the experimental OH dipole moment of 1.66 D. 85 The same calculations yielded largest principle quadrupole moments 74 for C 2 H 4 of 6.39 and 6.62 D Å, respectively; again agreeing well with the experimental value of 6.48 D Å. 86 The asymmetry in the quadrupole is very small, with the quadrupole moments for the other two axes being nearly identical.…”

Section: Computational Methodologysupporting

confidence: 78%

A Two Transition State Model for Radical−Molecule Reactions: Applications to Isomeric Branching in the OH−Isoprene Reaction

et al. 2007

View full text Add to dashboard Cite

A two transition state model is applied to the study of the addition of hydroxyl radical to ethylene. This reaction serves as a prototypical example of a radical-molecule reaction with a negative activation energy in the high-pressure limit. The model incorporates variational treatments of both inner and outer transition states. The outer transition state is treated with a recently derived long-range transition state theory approach focusing on the longest-ranged term in the potential. High-level quantum chemical estimates are incorporated in a variational transition state theory treatment of the inner transition state. Anharmonic effects in the inner transition state region are explored with direct phase space integration. A two-dimensional master equation is employed in treating the pressure dependence of the addition process. An accurate treatment of the two separate transition state regions at the energy and angular momentum resolved level is essential to the prediction of the temperature dependence of the addition rate. The transition from a dominant outer transition state to a dominant inner transition state is predicted to occur at about 130 K, with significant effects from both transition states over the 10 to 400 K temperature range. Modest adjustment in the ab initio predicted inner saddle point energy yields theoretical predictions which are in quantitative agreement with the available experimental observations. The theoretically predicted capture rate is reproduced to within 10% by the expression [4.93 × 10 -12 (T/298) -2.488 exp(-107.9/RT) + 3.33 × 10 -12 (T/298) 0.451 exp(117.6/RT); with R ) 1.987 and T in K] cm 3 molecules -1 s -1 over the 10-600 K range.

show abstract

Section: Computational Methodologysupporting

confidence: 78%

A Two Transition State Model for Radical−Molecule Reactions: Applications to Isomeric Branching in the OH−Isoprene Reaction

et al. 2007

View full text Add to dashboard Cite

show abstract

“…We have used Maroulis' theoretical values in our calculations, noting their good agreement with the estimates of Dagg et al [23] obtained from collision-induced absorption spectra measurements in ethene-rare gas mixtures. Whereas the two principal components of the optical-frequency polarizability tensor of a linear molecule can be deduced from experimental values of Po and ~v [26,27]; in the case of a nonlinear molecule, which we see from equation (19) [32] 4-157 _ 0"020 3-695 + 0"028 5-645 + 0-012 4"500 + 0"020 Sekino and Bartlett [33] 4-146 3.667 5.582 4.465…”

Section: Molecular Properties Of Ethenesupporting

confidence: 54%

“…The components of a~, are as for equation (23), except that the rotation angles now have the subscript 2: Expressing the T-tensors in space-fixed axes (x, y, z) is a simple matter since R is initially fixed along the z-axis. This is illustrated with the second-rank T-tensor [15] 1 1…”

Section: Describing the Relative Configuration Of Two Nonlinear Molecmentioning

confidence: 99%

“…This effectively bypasses repeated calculation of these values within the Gaussian quadrature routine, yielding a speed enhancement of a staggering 50 times; but has the Downloaded by [University of Windsor] at 09:05 19 November 2014 Table 1. Measurements of collision-induced 6"73 -13"33 absorption (CIA) spectra [22] Measurements of CIA spectra [23] 5"16 -10.41 Magnetizability anisotropy 4-67 -12-02 measurements [24] Measurements of induced 4"35 -10"99 birefringence + second dielectric virial coefficients + refractive index [25] MP2 theory [20] 5"43 MP4 theory [21] 5'370 -4-0'22…”

Section: The Integration Proceduresmentioning

confidence: 99%

See 1 more Smart Citation

Calculation and measurement of the second light-scattering virial coefficients of nonlinear molecules: a study of ethene

Couling

Graham

1996

Molecular Physics

View full text Add to dashboard Cite

The second light-scattering virial coefficient Bp of ethene has been extracted from measurements of the depolarization ratio p at gas pressures up to 3"2 MPa. The value calculated using our recent molecular tensor theory of Bp for axially symmetric molecules, underestimates the experimental value by 40%. A complete molecular tensor theory of Bp for nonlinear molecules is presented, and leads to a calculated value for ethene which is within 2 % of the experimental value.

show abstract

“…The same considerations hold for the case of ETH for which good experimental determination of the Θ tensor is available. 46,47 For MAC and DMA no experimental data are available to our knowledge. The values of the Θ zz component for ACE, MAC and DMA are also close to each other.…”

Section: Geometrical Energetic and Vibrational Features Of The Unsamentioning

confidence: 99%

Structure and Vibrational Features of Complexes between Unsaturated Hydrocarbons and Acidic Sites in Silica and Zeolites: An ab Initio Study

et al. 1996

View full text Add to dashboard Cite

Experimental vibrational data (FTIR) concerning the interaction of ethylene, acetylene, and methylacetylene with the acidic hydroxyls of amorphous silica (SiOH) and H-ZSM5 zeolite (Si(OH)Al) are compared with SCF/DZP and MP2/DZP results concerning the same molecules interacting with H 3 SiOH (SIL) and H 3 Si-(OH)AlH 3 (BRO), the minimal-size clusters mimicking the surface species. The interaction of dimethylacetylene with SIL and BRO has also been studied. Computed harmonic shifts in the O-H stretching frequency ∆ν h (OH) are in semiquantitative agreement with experiment, in that the experimental data are systematically underestimated by a factor of ≈ 1 / 3 at best: the main reason is the less acidic character of SIL and BRO with respect to SiOH and Si(OH)Al, which also causes a systematic underevaluation of the binding energies (BE). All this notwithstanding, calculated BE and ∆ν h (OH) values are good descriptors of the interactions, as a number of correlations may be drawn: (i) between the ∆ν h (OH) values on SIL and BRO, respectively (showing a constant ratio, identical with the ratio between experimental data); (ii) between BEs on SIL and BRO (showing the same ratio as strong bases on SiOH and Si(OH)Al); (iii) between BE and (∆ν h (OH)) 1/2 , in agreement with experimental data on ∆H°of interaction. The possible causes for the less acidic nature of SIL and BRO with respect to SiOH and Si(OH)Al are discussed. The nature of the interaction is predominantly electrostatic, in that SCF interaction energies are in semiquantitative agreement with those computed via a classical Coulombic expression using electrostatic-potential derived charges. However, a small electron transfer takes place from the base molecule to the acidic species, which parallels the strength of interaction and, within the same family of molecules, the ionization energy of the base molecules. The comparison between calculated and experimental values of C-H modes suggests that a secondary interaction takes place between the acidic hydrogen in acetylene and methylacetylene and a basic oxygen atom close to the active site.

show abstract

Collision-induced absorption in the far infrared region in ethylene – rare gas mixtures

Cited by 16 publications

References 0 publications

A Two Transition State Model for Radical−Molecule Reactions: Applications to Isomeric Branching in the OH−Isoprene Reaction

A Two Transition State Model for Radical−Molecule Reactions: Applications to Isomeric Branching in the OH−Isoprene Reaction

Calculation and measurement of the second light-scattering virial coefficients of nonlinear molecules: a study of ethene

Structure and Vibrational Features of Complexes between Unsaturated Hydrocarbons and Acidic Sites in Silica and Zeolites: An ab Initio Study

Contact Info

Product

Resources

About