Atomic force and scanning electron microscopy of atmospheric particles

Area of Science:

• Atmospheric science
• Geochemistry
• Materials science

Background:

• Atmospheric particles require accurate morphological and elemental analysis for environmental studies.
• Traditional methods may not fully capture particle volume and shape characteristics.

Purpose of the Study:

• To evaluate Atomic Force Microscopy (AFM) and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS) for atmospheric particle characterization.
• To develop a particle shape model using AFM for improved volume estimation.
• To compare mass measurements from AFM and SEM-EDS for marine aerosols.

Main Methods:

• Utilized AFM for height profile and relative volume measurements to create particle shape models.
• Employed SEM-EDS for elemental identification and mass content calculation.
• Calibrated EDS analysis with known composition particles for accurate quantification.
• Collected and analyzed aerosol samples at different altitudes (150 m and 500 m) above the Mediterranean Sea.

Main Results:

• AFM-derived volume measurements showed good agreement with SEM-EDS mass calculations for marine aerosols.
• Cylindrical shapes provided a more accurate volume estimation for soluble marine sulfate and nitrate aerosols compared to spherical or conical models.
• AFM enabled detailed geometrical analysis, complementing elemental mass data from SEM-EDS.

Conclusions:

• AFM is a valuable tool for detailed geometrical analysis and volume estimation of atmospheric particles.
• Combining AFM with SEM-EDS offers a comprehensive approach to atmospheric particle characterization.
• The study highlights the importance of appropriate geometric modeling for accurate aerosol volume determination.