ESEM Methodology for the Study of Ice Samples at Environmentally Relevant Subzero Temperatures: "Subzero ESEM"

Area of Science:

• Materials Science
• Cryogenics
• Microscopy

Background:

• Frozen aqueous solutions are vital in diverse fields like pharmaceuticals, food science, atmospheric chemistry, biology, and medicine.
• Maintaining thermodynamic equilibrium in ice samples at subzero temperatures is a significant experimental challenge.

Purpose of the Study:

• To develop and present an advanced environmental scanning electron microscope (ESEM) methodology for studying ice samples at environmentally relevant subzero temperatures.
• To enable the observation of intact ice samples under conditions that closely mimic their natural state.

Main Methods:

• Utilized an environmental scanning electron microscope (ESEM) for high-resolution imaging of ice samples at subzero temperatures.
• Incorporated ANSYS software simulations to model sample surface temperature and analyzed water vapor partial pressure.
• Monitored static ice samples over extended periods, addressing potential artifacts like sublimation and unwanted ice formation.

Main Results:

• Successfully characterized the true morphology changes in ice spheres containing salt upon aging.
• Investigated the morphology of ice spheres containing bovine serum albumin (BSA).
• Achieved nanometer resolution by combining static observations with dynamic ice sublimation processes.

Conclusions:

• The developed ESEM methodology provides a robust approach for observing ice samples at near-natural, subzero conditions.
• The technique is applicable to studying the aging and morphological changes of various ice-containing systems, including those with salts and biomolecules.
• This advanced methodology enhances the understanding of frozen solutions across multiple scientific disciplines.