Researchers at Pacific Northwest National Laboratory (PNNL) have developed an Atmospheric Pressure Environmental (APE) Chamber engineered to operate inside an Environmental Scanning Electron Microscope (ESEM) while maintaining fully controlled temperature, humidity, and pressure at ambient conditions.

The APE Chamber integrates: temperature control (-190°C to +20°C), relative humidity (0-100%), pressure from vacuum to 1 atm, and UV-Vis photochemical capabilities. UV-Vis irradiation, when combined with specific precursor gas introduction, can mimic ambient environment conditions that enable study of photochemical reactions.

Reducing sample distortion from vacuum conditions

Traditional SEM/ESEM capabilities distort sensitive samples such as aerosols, biological tissue, and soil particulates due to vacuum environments. The low-pressure conditions cause significant water and volatile loss from aerosol and biological samples, leading to structural deformation and chemical alteration. The APE Chamber preserves the native state of samples for accurate imaging and chemical characterization by enabling SEM chemical imaging at pressures up to 1 atmosphere. 

Enabling atmospheric pressure

The APE Chamber supports real-time chemical and physical process observation under atmospheric conditions. A thin SiNx window allows high electron transmission while maintaining atmospheric pressure around the sample. Gas, humidity, and UV-Vis control enable atmospheric aging and photochemical studies.

APE enables true ambient pressure SEM imaging, combined chemical/morphological/photochemical analysis, flexible modular chamber architecture, low-cost construction, and compatibility with diverse sample types.

INDUSTRY APPLICATIONS
Atmospheric aerosol research, rhizosphere and soil microscale chemistry, biological imaging without dehydration, photochemical reaction observations, and mineral-organic interface studies.