Open AccessResponse of the Surface Phase Transition to an Abrupt Pressure Change: Comparative Study of the 2D Gas–Liquid and 2D Fluid–Solid Phase Transitions
Author(s) -
Yosihito Kitayama,
Yosinobll Sakai,
Hiromu Asada
Publication year - 1998
Publication title -
adsorption science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.682
H-Index - 36
eISSN - 2048-4038
pISSN - 0263-6174
DOI - 10.1177/026361749801600506
Subject(s) - chemistry , phase transition , adsorption , exponential decay , desorption , phase (matter) , coalescence (physics) , graphite , relaxation (psychology) , analytical chemistry (journal) , thermodynamics , chromatography , organic chemistry , physics , psychology , social psychology , astrobiology , nuclear physics
The manner in which gaseous CH 4 and N 2 respond to an abrupt pressure change through adsorption and desorption on exfoliated graphite held at a temperature between 77 K and 90 K has been studied with particular emphasis on the role of the 2D (two-dimensional) Gas–Liquid phase transition of the second layer of adsorbed CH 4 and of the 2D Fluid–Solid phase transition of adsorbed N 2 . The pressure relaxation was found to consist of two exponential decay components: a fast one and a slow one. For CH 4 , the 2D Gas–Liquid phase transition is involved in the fast decay component with a time constant of 2–3 s, while the slow decay component with a time constant of 7–40 s is minor and has been attributed to ripening or coalescence processes in the adsorbed phase. In contrast, the 2D Fluid–Solid phase transition of N 2 involves both the fast decay component with a time constant of 2–3 s and the slow decay component with a time constant of 14–16 s, both having nearly equal magnitudes. The difference in the pressure response between the two phase transitions is discussed.