Development of Atmospheric Pressure Environmental (APE) Chamber for Chemical Imaging of Aerosol, Plant, and Soil Samples
EMSL Project ID
60902
Abstract
Maintaining low-pressure (∼2×10−6-10 Torr) inside the Environmental Scanning Electron Microscope (ESEM) chamber is the major challenge in pressure- and/or relative humidity (RH)-sensitive sample (e.g., organic aerosol particle, plant tissue, and biological samples) analysis. It can cause loss of water and volatile (up to 100%) and semivolatile organics species (up to 50%), resulting in mechanical sample deformation and misleading heterogeneous chemistry information. Thus, we propose to build an atmospheric pressure environmental (APE) chamber that can be integrated to the ESEM chamber for chemical imaging of samples and dynamic observation of real-time chemical, physical, and biochemical phenomena under controlled temperature (T), RH, and pressure (P). The APE chamber will be interfaced with the ESEM stage. RH-controlled (0-100%) gas (e.g., air to maintain pressure from ~0 to 1 atm and O3 for oxidation reaction) will be injected into the APE chamber. Samples will be loaded on a Peiter stage to allow T control (-5-40 °C). Sensors will monitor the APE chamber's T, RH, and P. A light probe, connected to UV or full visible spectrum light sources via optical fiber, will be equipped inside the APE chamber for photochemical reactions. A 20 nm thick silicon nitride (SiNx) membrane window will be on the top center of the APE chamber, allowing the acquiring of SEM images and Energy-dispersive X-ray (EDX) spectra with around 10 kV electron beam acceleration voltage. APE chamber will be made with EM-compatible conductive 3D printing materials to reduce costs and allow future upgrades. The APE chamber will be investigated to ensure it will not cause leakage or emit gas inside the ESEM chamber. We will optimize the distance between the SiNx window and sample to minimize the loss of electrons and X-rays and apply image enhancement techniques to improve the image quality. To evaluate the APE chamber, we will investigate the real-time morphology change of aerosol after ozonolysis and/or UV photolysis under ambient conditions, which cannot be observed with existing techniques due to the rapid reaction rate. Moreover, we will use it and SEM-EDX to see the transport of essential elements such as nitrogen and phosphorous from Synthetic Soil Habitats to microbes and roots.
Project Details
Start Date
2023-10-01
End Date
N/A
Status
Active
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members