Melting entropy of crystals determined by electron-beam-induced configurational disordering.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 38815089.
- Also identified by DOI 10.1126/science.adk3620.
- No licence information is recorded for this record.
- Because redistribution is not established, this page shows the abstract only. Follow the links below for the full text.
Abstract
Upon melting, the molecules in a crystal explore numerous configurations, reflecting an increase in disorder. The molar entropy of disorder can be defined by Boltzmann's formula Δ<i>S</i><sub>d</sub> = <i>R</i>ln(<i>W</i><sub>d</sub>), where <i>W</i><sub>d</sub> is the increase in the number of microscopic states, so far inaccessible experimentally. We found that the Arrhenius frequency factor <i>A</i> of the electron diffraction signal decay provides <i>W</i><sub>d</sub> through an experimental equation <i>A</i> = <i>A</i><sub>INT</sub><i>W</i><sub>d</sub>, where <i>A</i><sub>INT</sub> is an inelastic scattering cross section. The method connects Clausius and Boltzmann experimentally and supplements the Clausius approach, being applicable to a femtogram quantity of thermally unstable and biomolecular crystals. The data also showed that crystal disordering and crystallization of melt are reciprocal, both governed by the entropy change but manifesting in opposite directions.