Figure 2
Scanning curves in situ with SAXS. Points A and Α΄ are on the desorption boundary.
Notice that the low-Q upturn of curve A is about 1.5 times less than the corresponding upturn for curve 1 in Fig. 1. The amount desorbed between points A-A΄and C-C΄ is about the same. A fluctuation in the system may lead to an exchange of capillary condensate in neighbouring regions of the pore network, e.g. C-C΄ where a mass balance is preserved at the same relative pressure. The main figure shows the scattering curves at various values of p/po. Notice that the spinodal peaks at points C΄ and A coincide, although at low Q there is a difference, indicating a redistribution of the capillary condensate which is more clearly presented in the lower insert in terms of ΔI(Q). This redistribution is metastable, but is maintained by hysteresis effects. The magnitude of these effects is dependent on the steepness of the desorption boundary. The sum of the areas (green or yellow) are almost equal to zero, but the system rearranges the amount adsorbed from large clusters to neighboring pores, indicating local cavitation. The upper insert shows the points on the CH2Br2 desorption isotherm where SAXS measurements are conducted.
