A LEED study of adsorbed neon on graphite
1982; Elsevier BV; Volume: 115; Issue: 3 Linguagem: Inglês
10.1016/0039-6028(82)90381-8
ISSN1879-2758
AutoresS. Calisti, J. Suzanne, J. A. Venables,
Tópico(s)Quantum, superfluid, helium dynamics
ResumoNeon monolayers on graphite have been investigated by high resolution LEED in the range 14.5 < T < 7.5 K and 10−8 < p < 10−4 Torr. The fluid-solid transition line has the form ln(pTorr)= −AT + B, with A = 740 ± 45 K and B = 31.0 ± 2.8. The solid is an incommensurate rotated phase whose lattice parameter decreases and rotation angle increases away from the transition line. Comparison is made with other thermodynamic and diffraction studies, and a preliminary phase diagram is constructed. Extrapolation of these data to higher temperatures and pressure suggests that this rotated solid monolayer is stable up to 23–25 K (P = 3−10 Torr) at coverage x = 1, and is stable over the range 0.88 < x < 1.0 at T = 16 K (2 × 10−7 < p 1.5 × 10−2 Torr). Extrapolation to lower temperatures gives the 2D triple point pressure in the range p = (0.3−3) × 10−10 Torr. The steep slope of the fluid-solid transition line is consistent with the fluid phase having a high density (x≳0.80) in the temperature range studied.
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