A quasiclassical trajectory study of H+CO2: Angular and translational distributions, and OH angular momentum alignment

Kimberly S. Bradley, George C Schatz

Research output: Contribution to journalArticle

91 Citations (Scopus)

Abstract

We present a quasiclassical trajectory study of the H+CO2 reaction dynamics, with emphasis on product angular and translational distributions, and OH angular momentum alignment. A new potential surface has been developed for this study, based on modifications of a previously developed full dimensional empirical HCO2 potential surface. The modifications include correcting errors that cause the HO ⋯ CO dissociation barrier to be too loose, and adjusting the depth of the HCO2 minimum and the heights of several barriers, in order to bring them into agreement with their best estimates determined from ab initio calculations. We compare cross sections, energy partitioning, and mechanistic information calculated using the unmodified and modified surfaces with experimental results. Results from the modified surface improve the comparison with experiment for the product OH energy partitioning, but the product CO internal excitation is still high. The translational distributions have the same shape as measured distributions, and the average translational excitation matches some experiments but is lower than others. The angular distribution calculated at 2.6 eV on the modified surface is in good agreement with experimental results, showing both forward and backward scattered peaks, with a slight preference for backward scattering. By studying the average lifetime of the HOCO collision complex, we find that the lifetime is comparable to the rotational period so that there is considerable forward scattering (half rotation) and backward scattering (full rotation). The OH product angular momentum alignment indicates no preference for polarization of the OH rotational angular momentum vector. This result - an essentially isotropic distribution - agrees within the experimental uncertainty for measurements of OH Π(A′) polarization dependent differential cross sections and center-of-mass frame alignment parameters, but not with OH Π(A″)

Original languageEnglish
Pages (from-to)8464-8472
Number of pages9
JournalJournal of Chemical Physics
Volume106
Issue number20
Publication statusPublished - May 22 1997

Fingerprint

Angular momentum
angular distribution
angular momentum
alignment
Trajectories
trajectories
Carbon Monoxide
Scattering
Polarization
Forward scattering
products
Angular distribution
life (durability)
Experiments
cross sections
forward scattering
polarization
scattering
excitation
center of mass

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

A quasiclassical trajectory study of H+CO2 : Angular and translational distributions, and OH angular momentum alignment. / Bradley, Kimberly S.; Schatz, George C.

In: Journal of Chemical Physics, Vol. 106, No. 20, 22.05.1997, p. 8464-8472.

Research output: Contribution to journalArticle

@article{75b9c9e996d148beae00bfd7e1e0dfb8,
title = "A quasiclassical trajectory study of H+CO2: Angular and translational distributions, and OH angular momentum alignment",
abstract = "We present a quasiclassical trajectory study of the H+CO2 reaction dynamics, with emphasis on product angular and translational distributions, and OH angular momentum alignment. A new potential surface has been developed for this study, based on modifications of a previously developed full dimensional empirical HCO2 potential surface. The modifications include correcting errors that cause the HO ⋯ CO dissociation barrier to be too loose, and adjusting the depth of the HCO2 minimum and the heights of several barriers, in order to bring them into agreement with their best estimates determined from ab initio calculations. We compare cross sections, energy partitioning, and mechanistic information calculated using the unmodified and modified surfaces with experimental results. Results from the modified surface improve the comparison with experiment for the product OH energy partitioning, but the product CO internal excitation is still high. The translational distributions have the same shape as measured distributions, and the average translational excitation matches some experiments but is lower than others. The angular distribution calculated at 2.6 eV on the modified surface is in good agreement with experimental results, showing both forward and backward scattered peaks, with a slight preference for backward scattering. By studying the average lifetime of the HOCO collision complex, we find that the lifetime is comparable to the rotational period so that there is considerable forward scattering (half rotation) and backward scattering (full rotation). The OH product angular momentum alignment indicates no preference for polarization of the OH rotational angular momentum vector. This result - an essentially isotropic distribution - agrees within the experimental uncertainty for measurements of OH Π(A′) polarization dependent differential cross sections and center-of-mass frame alignment parameters, but not with OH Π(A″)",
author = "Bradley, {Kimberly S.} and Schatz, {George C}",
year = "1997",
month = "5",
day = "22",
language = "English",
volume = "106",
pages = "8464--8472",
journal = "Journal of Chemical Physics",
issn = "0021-9606",
publisher = "American Institute of Physics Publising LLC",
number = "20",

}

TY - JOUR

T1 - A quasiclassical trajectory study of H+CO2

T2 - Angular and translational distributions, and OH angular momentum alignment

AU - Bradley, Kimberly S.

AU - Schatz, George C

PY - 1997/5/22

Y1 - 1997/5/22

N2 - We present a quasiclassical trajectory study of the H+CO2 reaction dynamics, with emphasis on product angular and translational distributions, and OH angular momentum alignment. A new potential surface has been developed for this study, based on modifications of a previously developed full dimensional empirical HCO2 potential surface. The modifications include correcting errors that cause the HO ⋯ CO dissociation barrier to be too loose, and adjusting the depth of the HCO2 minimum and the heights of several barriers, in order to bring them into agreement with their best estimates determined from ab initio calculations. We compare cross sections, energy partitioning, and mechanistic information calculated using the unmodified and modified surfaces with experimental results. Results from the modified surface improve the comparison with experiment for the product OH energy partitioning, but the product CO internal excitation is still high. The translational distributions have the same shape as measured distributions, and the average translational excitation matches some experiments but is lower than others. The angular distribution calculated at 2.6 eV on the modified surface is in good agreement with experimental results, showing both forward and backward scattered peaks, with a slight preference for backward scattering. By studying the average lifetime of the HOCO collision complex, we find that the lifetime is comparable to the rotational period so that there is considerable forward scattering (half rotation) and backward scattering (full rotation). The OH product angular momentum alignment indicates no preference for polarization of the OH rotational angular momentum vector. This result - an essentially isotropic distribution - agrees within the experimental uncertainty for measurements of OH Π(A′) polarization dependent differential cross sections and center-of-mass frame alignment parameters, but not with OH Π(A″)

AB - We present a quasiclassical trajectory study of the H+CO2 reaction dynamics, with emphasis on product angular and translational distributions, and OH angular momentum alignment. A new potential surface has been developed for this study, based on modifications of a previously developed full dimensional empirical HCO2 potential surface. The modifications include correcting errors that cause the HO ⋯ CO dissociation barrier to be too loose, and adjusting the depth of the HCO2 minimum and the heights of several barriers, in order to bring them into agreement with their best estimates determined from ab initio calculations. We compare cross sections, energy partitioning, and mechanistic information calculated using the unmodified and modified surfaces with experimental results. Results from the modified surface improve the comparison with experiment for the product OH energy partitioning, but the product CO internal excitation is still high. The translational distributions have the same shape as measured distributions, and the average translational excitation matches some experiments but is lower than others. The angular distribution calculated at 2.6 eV on the modified surface is in good agreement with experimental results, showing both forward and backward scattered peaks, with a slight preference for backward scattering. By studying the average lifetime of the HOCO collision complex, we find that the lifetime is comparable to the rotational period so that there is considerable forward scattering (half rotation) and backward scattering (full rotation). The OH product angular momentum alignment indicates no preference for polarization of the OH rotational angular momentum vector. This result - an essentially isotropic distribution - agrees within the experimental uncertainty for measurements of OH Π(A′) polarization dependent differential cross sections and center-of-mass frame alignment parameters, but not with OH Π(A″)

UR - http://www.scopus.com/inward/record.url?scp=0000614329&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0000614329&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0000614329

VL - 106

SP - 8464

EP - 8472

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 20

ER -