Since this mixture has a larger heat capacity than liquid nitrogen, it can quickly freeze the sample without boiling off and therefore prevent aggregation during the cooling process . In samples frozen with liquid nitrogen alone, solvent crystallization is observed whereas samples frozen in the liquid propane/ethane mixture exhibit amorphous frozen solvent (as observed under crosspolarized optical microscopy). The top coverslip is separated while submerged in liquid nitrogen and the sample is then quickly transferred to a sealed Linkam stage chamber (LTS420) which is held at -100 °C in a nitrogen atmosphere. The temperature is raised to -80 °C (0.5 °C/min) for chlorobenzene and 90% chlorobenzene/10% dimethylformamide solutions while vacuum is applied for ~6 hours in order to fully sublimate the solvent while preventing melting. The sample is then imaged by SEM (JEOL JSM-7000F) at 25 kV accelerating voltage.