title: Molecular mobility in the supercooled and glassy states of nizatidine and perphenazine.
abstract: The dielectric properties of two pharmaceuticals nizatidine and perphenazine were investigated in the supercooled liquid and glassy states by broadband dielectric spectroscopy. Two relaxation processes were observed in both the pharmaceuticals. The relaxation process observed above the glass transition temperature is the structural alpha relaxation and below the glass transition temperature is the gamma relaxation of intramolecular origin. The Johari-Goldstein beta relaxation coming from the motion of the entire molecule is found to be hidden under the structural relaxation peak in both the pharmaceuticals.
authors.affiliation: Department of Physics, M.E.S Keveeyam College, Valanchery, 676 552 Malappuram, Kerala, India. Electronic address: sailajaurpayil@gmail.com.
authors.forename: U
authors.initials: U
authors.lastname: Sailaja
authors.affiliation: Department of Physics, University of Calicut, 673 635, Kerala, India.
authors.forename: M
authors.initials: M
authors.lastname: Shahin Thayyil
authors.affiliation: Department of Physics, School of Physical, Chemical and Applied Sciences, Pondicherry University, Puducherry, 605 014, India.
authors.forename: N S
authors.initials: NS
authors.lastname: Krishna Kumar
authors.affiliation: Department of Physics, School of Physical, Chemical and Applied Sciences, Pondicherry University, Puducherry, 605 014, India.
authors.forename: G
authors.initials: G
authors.lastname: Govindaraj
authors.affiliation: CNR-IPCF, Dipartimento di Fisica, Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy.
authors.forename: K L
authors.initials: KL
authors.lastname: Ngai
mesh_terms: D058266:Dielectric Spectroscopy / Q000379:methods; D005898:Glass / Q000737:chemistry; D009038:Motion; D016567:Nizatidine / Q000737:chemistry*; D010546:Perphenazine / Q000737:chemistry*; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D013696:Temperature; D044366:Transition Temperature
chemical_list: D004364:Pharmaceutical Preparations; D010546:Perphenazine; D016567:Nizatidine
keywords: Broadband dielectric spectroscopy; Dielectric relaxation strength; Glass transition; Nizatidine; Perphenazine