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Scanning Mobility Particle Sizer (SMPS)

The SMPS is an instrument used for measuring particle size distributions in the nanometer range.

Data Format

  • File format:
    • .txt files (tab-delimited) from older AIM versions (8.x, 9.x)
    • .csv files (comma-delimited) from newer AIM versions (10.x+)
  • Sampling frequency: Variable
  • File naming pattern: *.txt or *.csv
  • Timestamp formats:
    • mm/dd/yy HH:MM:SS (US format, older versions)
    • mm/dd/yyyy HH:MM:SS (US format, newer versions)
    • dd/mm/yyyy HH:MM:SS (EU format)

Measurement Parameters

The SMPS provides particle size distribution measurements:

  • Size range: 11.8-593.5 nm (default)
  • Output: Number concentration (dN/dlogDp) for each size bin
  • Total particle concentration (particles/cm³)

Data Processing

Data Reading

  • Automatically detects and skips header rows
  • Supports multiple date formats based on AIM version
  • Handles transposed data formats
  • Extracts and sorts particle size columns numerically
  • Validates size range against expected settings

Quality Control

  • Filters by specified particle size range
  • Ensures temporal data completeness (minimum 6 measurements/hour)
  • Applies minimum total concentration threshold (2000 particles/cm³)
  • Removes physically implausible high concentrations (>1×10⁶ dN/dlogDp)
  • Special filtering for large particles (>400 nm exceeding 4000 dN/dlogDp)

Output Data

The processed data contains:

  • Time index: Data acquisition time
  • Size bins: Number concentration for each particle size
  • Total concentration: Integrated particle number concentration

Notes

  • Different AIM software versions may produce different file formats
  • Size range validation ensures data quality
  • Special handling for large particle measurements
  • Automatic format detection and parsing