Positronium lifetime in supercooled 1-butanol: Search for polyamorphism

Isothermal transformations of supercooled 1-butanol were observed by positron lifetime spectroscopy. Transformation rate is the highest near 150 K, whereas below 140 K it slows down becoming undetectable below 120 K. At the temperature range of 123–135 K the ortho-positronium lifetime achieves the final value which is higher than the one observed for crystalline phase. This is an indication of transition to a new (meta)stable structure, in which the ortho-positronium lifetime and intensity reach values that are intermediate between liquid and crystal phases. Consistency of positron annihilation data with the concept of two coexisting phases is discussed.