title: Molecular reorientations in liquid crystals pentyloxybenzylidine hexylanilene (PBHA) and butyloxybenzylidine octylanilene (BBOA).
abstract: Molecular reorientational motions in undeuterated pentyloxybenzylidine hexylanilene (PBHA or 5O.6) and butyloxybenzylidine octylanilene (BBOA or 4O.8) as studied by the quasielastic neutron scattering (QENS) technique in their different mesophases are reported. Models are built up in stages to account for the experimental elastic incoherent structure factor (EISF). It is found that there exist simultaneous reorientational motions of the chain group and the reorientational motions of the whole molecule around its molecular axis in the smectic- G, smectic- B, and smectic- C phases. In smectic- A and nematic phases, additional body axis fluctuations are found to exist in both 5O.6 and 4O.8 systems. The average amplitude of body axis fluctuations is found to be approximately 15 degrees and 25 degrees, respectively, in the smectic- A and nematic phases of 5O.6, and approximately 14 degrees and 29 degrees, respectively, in 4O.8.
authors.affiliation: Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India. smitra@apsara.barc.ernet.in
authors.forename: S
authors.initials: S
authors.lastname: Mitra
authors.forename: K
authors.initials: K
authors.lastname: Venu
authors.forename: I
authors.initials: I
authors.lastname: Tsukushi
authors.forename: S
authors.initials: S
authors.lastname: Ikeda
authors.forename: R
authors.initials: R
authors.lastname: Mukhopadhyay