Li Dongxu, Jiang Xu, Yang Bin, Rice Stuart A
Department of Chemistry and The James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA.
J Chem Phys. 2005 Jun 8;122(22):224702. doi: 10.1063/1.1924544.
We report the results of measurements of x-ray reflectivity and grazing incidence x-ray diffraction from the liquid-vapor interfaces of four dilute alloys of Bi in Ga with mole fractions x(Bi)=0.0032, 0.0023, 0.00037, and 0.000037. The monolayer coverage of the alloys with x(Bi)=0.0023, and x(Bi)=0.00037 is about 0.85 and only very slightly temperature dependent. The monolayer coverage in the lowest-concentration alloy, with x(Bi)=0.000037, ranged from 0.82 at 29 degrees C to 0.58 at 110 degrees C. In none of these alloys, down to the lowest temperature used, 29 degrees C, can we find any evidence for crystallization of the Bi monolayer that segregates as the outermost stratum of the liquid-vapor interface. Drawing on theoretical arguments we propose that the transitions inferred from the second-harmonic generation and plasma generation studies of dilute Bi in Ga alloys are from the liquid state to the hexatic state of the Bi monolayer. The data for the alloy with x(Bi)=0.000037 suggest that near 80 degrees C there is a disordered phase-to-disordered phase transition.
我们报告了对四种镓铋稀合金（摩尔分数x(Bi)=0.0032、0.0023、0.00037和0.000037）液 - 气界面的X射线反射率和掠入射X射线衍射测量结果。x(Bi)=0.0023和x(Bi)=0.00037的合金的单层覆盖率约为0.85，且仅略微依赖于温度。最低浓度合金（x(Bi)=0.000037）的单层覆盖率在29℃时为0.82，在110℃时为0.58。在这些合金中，直至使用的最低温度29℃，我们都未发现任何证据表明作为液 - 气界面最外层分离的铋单层发生结晶。基于理论论证，我们提出从镓铋稀合金的二次谐波产生和等离子体产生研究推断出的转变是铋单层从液态到六次近晶态的转变。x(Bi)=0.000037合金的数据表明，在80℃附近存在无序相到无序相的转变。
