Collisional depolarization of NO(A) by He and Ar studied by quantum beat spectroscopy

Zeeman and hyperfine quantum beat spectroscopies have been used to measure the total elastic plus inelastic angular momentum depolarization rate constants at 300 K for NO (A 2 σ+) in the presence of He and Ar. In the case of Zeeman quantum beats it is shown how the applied magnetic field can be used...

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Main Authors: Brouard, M, Chadwick, H, Chang, Y, Cireasa, R, Eyles, C, La Via, A, Screen, N, Aoiz, F, Klos, J
Format: Journal article
Language:English
Published: 2009
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author Brouard, M
Chadwick, H
Chang, Y
Cireasa, R
Eyles, C
La Via, A
Screen, N
Aoiz, F
Klos, J
author_facet Brouard, M
Chadwick, H
Chang, Y
Cireasa, R
Eyles, C
La Via, A
Screen, N
Aoiz, F
Klos, J
author_sort Brouard, M
collection OXFORD
description Zeeman and hyperfine quantum beat spectroscopies have been used to measure the total elastic plus inelastic angular momentum depolarization rate constants at 300 K for NO (A 2 σ+) in the presence of He and Ar. In the case of Zeeman quantum beats it is shown how the applied magnetic field can be used to allow measurement of depolarization rates for both angular momentum orientation and alignment. For the systems studied here, collisional loss of alignment is more efficient than loss of orientation. In the case of NO (A) with He, and to a lesser extent NO (A) with Ar, collisional depolarization is found to be a relatively minor process compared to rotational energy transfer, reflecting the very weak long-range forces in these systems. Detailed comparisons are made with quantum mechanical and quasiclassical trajectory calculations performed on recently developed potential energy surfaces. For both systems, the agreement between the calculated depolarization cross sections and the present measurements is found to be very good, suggesting that it is reasonable to consider the NO (A) bond as frozen during these angular momentum transferring collisions. A combination of kinematic effects and differences in the potential energy surfaces are shown to be responsible for the differences observed in depolarization cross section with He and Ar as a collider. © 2009 American Institute of Physics.
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spelling oxford-uuid:5efb771b-8f3a-4508-a2be-cab1f76242742022-03-26T17:44:04ZCollisional depolarization of NO(A) by He and Ar studied by quantum beat spectroscopyJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:5efb771b-8f3a-4508-a2be-cab1f7624274EnglishSymplectic Elements at Oxford2009Brouard, MChadwick, HChang, YCireasa, REyles, CLa Via, AScreen, NAoiz, FKlos, JZeeman and hyperfine quantum beat spectroscopies have been used to measure the total elastic plus inelastic angular momentum depolarization rate constants at 300 K for NO (A 2 σ+) in the presence of He and Ar. In the case of Zeeman quantum beats it is shown how the applied magnetic field can be used to allow measurement of depolarization rates for both angular momentum orientation and alignment. For the systems studied here, collisional loss of alignment is more efficient than loss of orientation. In the case of NO (A) with He, and to a lesser extent NO (A) with Ar, collisional depolarization is found to be a relatively minor process compared to rotational energy transfer, reflecting the very weak long-range forces in these systems. Detailed comparisons are made with quantum mechanical and quasiclassical trajectory calculations performed on recently developed potential energy surfaces. For both systems, the agreement between the calculated depolarization cross sections and the present measurements is found to be very good, suggesting that it is reasonable to consider the NO (A) bond as frozen during these angular momentum transferring collisions. A combination of kinematic effects and differences in the potential energy surfaces are shown to be responsible for the differences observed in depolarization cross section with He and Ar as a collider. © 2009 American Institute of Physics.
spellingShingle Brouard, M
Chadwick, H
Chang, Y
Cireasa, R
Eyles, C
La Via, A
Screen, N
Aoiz, F
Klos, J
Collisional depolarization of NO(A) by He and Ar studied by quantum beat spectroscopy
title Collisional depolarization of NO(A) by He and Ar studied by quantum beat spectroscopy
title_full Collisional depolarization of NO(A) by He and Ar studied by quantum beat spectroscopy
title_fullStr Collisional depolarization of NO(A) by He and Ar studied by quantum beat spectroscopy
title_full_unstemmed Collisional depolarization of NO(A) by He and Ar studied by quantum beat spectroscopy
title_short Collisional depolarization of NO(A) by He and Ar studied by quantum beat spectroscopy
title_sort collisional depolarization of no a by he and ar studied by quantum beat spectroscopy
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