Surface-induced atomic layering in liquid gallium has been observed using x-ray reflectivity, ultrahigh vacuum conditions, and sputtered clean surfaces. Reflectivity data, collected on a supercooled liquid sample to momentum transfers as large as $q_z=3.0\mathrm{}{Å}^{-1\mathrm{}}$, exhibit a strong maximum near 2.4 Å ${}^{-1\mathrm{}}$ indicating a layer spacing that is comparable to its atomic dimensions. The amplitude of the electron density oscillations decays with a characteristic length of 6 Å. This is unexpectedly twice that of recent results for Hg, and the difference may be related to covalent bonding or supercooling.

• Received 10 March 1995

DOI:https://doi.org/10.1103/PhysRevLett.75.2498