TY - JOUR A1 - Kahlau, R. A1 - Gnutzmann, Tanja A1 - Emmerling, Franziska A1 - Rademann, K. A1 - Rössler, E.A. T1 - Quinaldine: Accessing two crystalline polymorphs via the supercooled liquid JF - The journal of chemical physics N2 - Quinaldine (2-methyl quinoline) is a liquid at room temperature, which can be supercooled to reach finally the glassy state. By heating the glass above the glass transition temperature Tg = 180 K the sample performs two subsequent transitions into, likewise, dielectrically active phases. Thus, the reorientational relaxations of these phases as well as the kinetics of the phase transitions can be tracked in a highly resolved way by dielectric spectroscopy. X-ray diffraction analysis clearly shows two structurally different crystalline phases in addition to the supercooled liquid. Calorimetric measurements support the notion of first order phase transitions, occurring irreversibly in the supercooled regime, and suggest that the intermediate crystalline phase is metastable, too. Analyzing the quite distinct dielectric relaxation strengths, we discuss the possible nature of the two crystalline phases. Additionally, a very similar behavior to quinaldine is observed for 3-methyl quinoline, indicating a broad field of polymorphism among the quinoline derivatives. KW - Calorimetry KW - Dielectric liquids KW - Dielectric relaxation KW - Glass transition KW - Liquid structure KW - Organic compounds KW - Polymorphism KW - Supercooling KW - X-ray diffraction PY - 2012 DO - https://doi.org/10.1063/1.4738583 SN - 0021-9606 SN - 1089-7690 VL - 137 IS - 5 SP - 054505-1 - 054505-10 PB - American Institute of Physics CY - Melville, NY AN - OPUS4-26347 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -