• Login
    View Item 
    •   NM-AIST Home
    • Materials, Energy, Water and Environmental Sciences
    • PhD Theses and Dissertations [MEWES]
    • View Item
    •   NM-AIST Home
    • Materials, Energy, Water and Environmental Sciences
    • PhD Theses and Dissertations [MEWES]
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Theoretical study of structure, vibrational spectra and thermodynamic properties of cluster ions existing in vapours over barium dihalides

    Thumbnail
    View/Open
    Fulltext (3.306Mb)
    Date
    2017-12
    Author
    Jacob, Fortunatus
    Metadata
    Show full item record
    Abstract
    Computational and theoretical methods were employed to study the structure, vibrational spectra and thermodynamic properties of cluster ions that were detected earlier in saturated vapour over barium dihalides. The equilibrium geometrical parameters and vibrational spectra were computed for the ions BaX3‒, Ba2X3+, Ba3X5+, Ba4X7+ and Ba5X9+ (X= F, Br or I); the DFT/B3P86 and MP2 methods with triple-zeta valence basis sets were used. The ions BaX3‒, Ba2X3+, Ba3X5+ and Ba5X9+ were confirmed to correspond to D3h point group of symmetry and Ba4X7+ to C2v configuration. Alternative structures for the cluster ions have been considered but no isomers were identified. The structural parameters and frequencies calculated with different theoretical approaches appeared to be not much sensitive regarding the methods and basis sets used. The enthalpies of ion molecular reactions were obtained both theoretically through the total energies of participants and based on experimental data through the equilibrium constants measured earlier. The enthalpies of formation ΔfHo(0) of the ions have been determined (in kJ mol–1): ‒1356  4 (BaF3‒); ‒1039  12 (Ba2F3+); ‒2179  16 (Ba3F5+); ‒3277  35 (Ba4F7+); ‒4316  22 (Ba5F9+); ‒858  6 (BaBr3‒); ‒293  10 (Ba2Br3+); ‒982  20 (Ba3Br5+); ‒1644  30 (Ba4Br7+); ‒2282  17 (Ba5Br9+); ‒709  6, (BaI3‒); ‒96  12 (Ba2I3+); ‒654  17 (Ba3I5+); ‒1177  20 (Ba4I7+); ‒1686  20 (Ba5I9+). The dimer molecules existing in vapours over the respective barium dihalides were studied, the thermodynamic properties and vapour compositions of their isomers were computed. For Ba2F4, Ba2Cl4 and Ba2Br4, three isomers of C3v, C2v and C2h symmetries were confirmed to exist while for Ba2I4 only two isomers, C3v and C2h were confirmed. For all isomers, the pyramidal isomer (C3v), was observed to be predominant at lower temperatures up to about 700 K followed by trans- and cis-isomers. The pyramidal isomer possesses higher magnitude of enthalpy of dissociation reaction and hence more stable than other isomers at ambient temperature. The enthalpies of formation of the C3v isomers were obtained (in kJ mol‒1): ‒1874  2 (Ba2F4); ‒1236  7 (Ba2Cl4); ‒1023  8 (Ba2Br4); ‒787  11 (Ba2I4).
    URI
    http://dspace.nm-aist.ac.tz/handle/123456789/226
    Collections
    • PhD Theses and Dissertations [MEWES]

    Nelson Mandela-AIST copyright © 2021  DuraSpace
    Theme by 
    Atmire NV
     

     

    Browse

    All PublicationsCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsThis CollectionBy Issue DateAuthorsTitlesSubjects

    My Account

    LoginRegister

    Nelson Mandela-AIST copyright © 2021  DuraSpace
    Theme by 
    Atmire NV