Kr and Xe on NaCl(100): pure phases and their miscibility

Properties of a Suggested Commensurate Monolayer Solid of Kr/NaCl(001)

“…The diffraction pattern would be a way to discriminate between the p ( × 1) and (2 × 2) commensurate lattices because of the doubling of the unit cell dimensions in the latter. There would be extra diffraction spots for the (2 × 2) case and the pattern would be only slightly different (alternating extinctions along the x̂ and ŷ axes) from what might be observed for two perpendicular domains of the (1 × 2) structure proposed by Budde et al…”

“…The dynamical stability of the commensurate monolayer lattices is tested by solving for the frequencies of lattice normal modes, scanning wave vectors in the first Brillouin zone. For small values of Ω, the (1 × 1) lattice is dynamically unstable as noted by Budde et al However, the (1 × 2) lattice they proposed is also dynamically unstable then. The (2 × 2) is dynamically stable and degenerates to the (1 × 1) lattice at large enough Ω, typically for Ω > 1.1 meV in these calculations.…”

“…In this context, the monolayer solid of krypton on the (001) face of NaCl might be relatively simple because the 3D nearest-neighbor spacing of Kr at low temperature is L nn = 3.99 Å, and the low-temperature lattice constant of the square surface lattice of NaCl(001) is scriptl = 3.96 Å. Experiments − on Kr/NaCl(001) show a remarkable degree of contradiction, although there is agreement that the basic spatial arrangement of the monolayer Kr is a square lattice. Further, as will be shown here, modeling of the Kr/NaCl(001) monolayer solid depends on corrugation energy terms that are poorly known and that admit complex structures.…”

“…There are several remarkable features of the Kr/NaCl(001) experiments that become evident when the observations are compared against other physisorbed krypton layers. Besides the occurrence of the square lattice, − there is the quite narrow chemical potential range of stability of the monolayer solid before the bilayer is formed . There also is the question of stability relative to the 2D triangular lattice and to uniaxial compression from the square lattice.…”

“…Besides the occurrence of the square lattice, 7À9 there is the quite narrow chemical potential range of stability of the monolayer solid before the bilayer is formed. 8 There also is the question of stability relative to the 2D triangular lattice and to uniaxial compression from the square lattice.…”