| Autor: |
Werner Press, B. Burandt, S. Haussühl |
| Rok vydání: |
1993 |
| Předmět: |
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| Zdroj: |
Physical Review Letters. 71:1188-1191 |
| ISSN: |
0031-9007 |
| DOI: |
10.1103/physrevlett.71.1188 |
| Popis: |
We present the first observations of near-surface critical phenomena of a phase transition in a molecular solid showing both an order-disorder and a strong displacive component. The surface x-ray scattering experiments were performed on an ${\mathrm{NH}}_{4}$Br single crystal (${\mathit{T}}_{\mathit{c}}$=235 K). For the order parameter they show a crossover from a power law with the bulk critical exponent \ensuremath{\beta}=0.3\ifmmode\pm\else\textpm\fi{}0.05 to a surface behavior with exponent ${\mathrm{\ensuremath{\beta}}}_{1}$=0.8\ifmmode\pm\else\textpm\fi{}0.1. From the diffuse intensity we have determined the critical exponents ${\mathrm{\ensuremath{\eta}}}_{\mathrm{\ensuremath{\parallel}}}$=1.3\ifmmode\pm\else\textpm\fi{}0.15, \ensuremath{\nu}=0.5\ifmmode\pm\else\textpm\fi{}0.15, and the correlation length ${\ensuremath{\xi}}_{0}^{+}$=4\ifmmode\pm\else\textpm\fi{}0.5 \AA{}. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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