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          Institute: MPI für medizinische Forschung     Collection: Forschungsgruppe Prof. Dr. Haeberlen     Display Documents



ID: 568748.0, MPI für medizinische Forschung / Forschungsgruppe Prof. Dr. Haeberlen
ND44 and NH3D+ dynamics in ammonium persulphate. II: Transition from low−to−high−temperature regime
Translation of Title:ND<SUP>4</SUP><SUB>4</SUB> and NH<SUB>3</SUB>D<SUP>+</SUP> dynamics in ammonium persulphate. II: Transition from low−to−high−temperature regime
Authors:Schmidt, Thorsten; Potrzebowski, M. J.; Schmitt, U.; Grossmann, G.; Haeberlen, Ulrich; Ganicz, K.; Olejniczak, Zbigniew; Olejniczak, Zbigniew; Lalowicz, Z. T.; Ciesielski, W.
Language:English
Date of Publication (YYYY-MM-DD):2002-12-01
Title of Journal:Journal of Chemical Physics
Journal Abbrev.:J. Chem. Phys.
Volume:117
Issue / Number:21
Start Page:9818
End Page:9827
Review Status:Peer-review
Audience:Experts Only
Intended Educational Use:No
Abstract / Description:The transition of the dynamics of ND4
1 ions in ammonium persulphate, dominated at low
temperatures by coherent uniaxial rotational tunnelling about one specific N−D bond ˜the preferred
bond! and, at high temperatures, by frequent stochastic jumps about all N−D bonds is elucidated
with deuteron spin−lattice relaxation measurements, selective saturation experiments and deuteron
NMR line shape analyses. Between 20 and 35 K, the coherent uniaxial tunnelling is superseded by
thermally activated stochastic jumps about the same bond with kinetic parameters kdyn
0
510(11.560.5) s21 and Edyn
a 5(3.660.3) kJ/mol. At higher temperatures, thermally activated
stochastic jumps about the other N−D bonds set in. Their kinetic parameters are kst
0
510(12.260.5) s21 and Est
a5(7.860.5) kJ/mol. From the primary and secondary tunnelling observed
at low temperatures we infer the heights of the potentials which hinder rotations of the ND4
1 ions
about the preferred and any other N−D bond. These heights, minus the rotator's ground state energy,
are about 25% larger than, respectively, Edyn
a and Est
a . The kinetic parameters of the two stochastic
processes are such that the essentially uniaxial coherent and then incoherent dynamics at low
temperatures is superseded at the decomposition temperature of the compound by stochastic
reorientational jumps which reflect the basic tetrahedral symmetry of the ammonium ion
Last Change of the Resource (YYYY-MM-DD):--
External Publication Status:published
Document Type:Article
Communicated by:Wulf Kaiser
Affiliations:MPI für medizinische Forschung/Forschungsgruppe Prof. Dr. Haeberlen
Identifiers:LOCALID:5395
URI:http%3A%2F%2Fojps.aip.org%2Fgetpdf%2Fservlet%2FGet...
URI:http%3A%2F%2Fojps.aip.org%2Fjournals%2Fdoc%2FJCPSA...
URI:http%3A%2F%2Fjcp.aip.org%2Fresource%2F1%2Fjcpsa6%2...
DOI:10.1063%2F1.1518024
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