Pinwheel phases, orientational ordering

Figure 49. Phase diagram of CO physisorbed on graphite with the following phases commensurate orientationally disordered (>/3 x -s/3)/J30° solid phase (CD), commensurate orientationally ordered herringbone phase (HB), head-tail (dipolar) ordered commensurate herringbone phase (DHB), fluid (F), reentrant fluid (RF), incommensurate orientationally disordered solid (ID), incommensurate orientationally ordered pinwheel phase (PW), second-layer orientationally disordered solid (2SD), second-layer liquid (2L), second-layer vapor (2V), second-layer fluid (2F), bilayer orientationally ordered solid (BO) the parentheses are included for clarity only. The solid lines are based on experimental results, whereas the dashed lines are speculative. Note that the phase boundary (ID + CD) RF and the orientational disordering temperamre of the BO phase are unknown. Coverage unity corresponds to a coverage of CO forming a complete ( /3 x Vs) commensurate monolayer. (The phase diagram is based on Fig. 1 of Ref. 112, Fig. 2 of Ref. 113, and Refs. 380 and 381.

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