Distinguishing the glass, crystal, and quasi-liquid layer in 1-methylnaphthalene by using fluorescence signatures

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Publikace nespadá pod Pedagogickou fakultu, ale pod Přírodovědeckou fakultu. Oficiální stránka publikace je na webu muni.cz.
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ZEZULA Jan MUŽÍK David BACHLER Johannes LOERTING Thomas HEGER Dominik

Rok publikování 2023
Druh Článek v odborném periodiku
Časopis / Zdroj Journal of Luminescence
Fakulta / Pracoviště MU

Přírodovědecká fakulta

Citace
www https://doi.org/10.1016/j.jlumin.2023.119917
Doi http://dx.doi.org/10.1016/j.jlumin.2023.119917
Klíčová slova Condensed phases; Luminescence; Surface premelting; Quasi-liquid layer; Cold crystallization; Excimers
Popis The fluorescence of crystalline 1-methylnaphthalene is monomer-like, while liquid and glass exhibit excimeric emissions. We detail the temperature dependence of the fluorescence emission and excitation spectra in the range of between 77 K and 295 K. These spectra provide exhaustive information about the state and temperature of 1-methylnaphthalene. The glass, formed by abrupt quenching in liquid nitrogen or methane, devitrifies at (155 +/- 5) K, and the liquid then undergoes cold crystallization at around 170 K. In 1-methylnaphthalene crystals, an excimeric emission appears at approximately 40 K below the melting point, a process we ascribe to the formation of dimers due to surface premelting; such a quasi-liquid layer exists at the surface well below the freezing point, remaining uncrystallized. The premelted layer is clearly distinguishable from the bulk glass via fluorescence spectroscopy, which facilitates state identification.
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