Onset detection of solid-state phase transition in estrogen-like chemical via terahertz transmission spectroscopy

Solid-state phase transition onset in an endocrine-disrupting estrogen-like chemical (1,4-naphthol) is detected using terahertz transmission spectroscopy. The appearance of two absorption peaks and the sudden upsurge of terahertz-radiation power at 210 K indicate the onset of the solid-state phase transition. Differential scanning microscopy reveals a first-order phase transition at around 240 K while temperature-dependent x-ray diffraction analysis shows the occurrence of such phenomenon also at around 240 K. This demonstrates the sensitivity of the terahertz spectroscopic technique to phase transition since it provides a signal before such phenomenon actually occurs.