AMS

January 28, 2016 | Infrastructure

High Resolution Aerosol Mass Spectrometer (HRToF-AMS)

Technical features

Dimensions in cm: 105 x 61 x 135

Weight: about 170 Kg. (with transport box about 280 Kg)

Universal power supply 110VAC / 60Hz or 220VAC / 50Hz

Vacuum system operating at 24 VDC

Electric power: about 600W

Particle size classification and chemical analysis of sub-micronic aerosols

Aerodynamic range: 40 nm - 1 µm

ToFMS: The time-of-flight spectrometer can work in low resolution (V) or high resolution (W) configuration:

  Limit of detection   Resolution

  Mass range
  µg / m3
HR-ToF-AMS (V-mode)   0.003

  Single (1000)

   1-1200
HR-ToF-AMS (W-mode)   0.05   4000   1-1200

 Detection limits determined by acquiring 1 minute and with a S / N 3/1 ratio. The limit is calculated on the nitrate ion (for organic species it is 1 times lower detectability, 2 times lower for sulphate while ammonium is 20 times lower).

Measured parameters and output formats

All processing is provided in HDF format (Hierarchical Data Format) and performed through IGOR Pro 6.2 applications

  • Aerodynamic distribution of aerosols in the range 40nm - 1µm
  • Mass spectra of inorganic substances (nitrates, sulphates, ammonium) and speciation of organic substances by classes of compounds (saturated and unsaturated hydrocarbons, oxygenated hydrocarbons, etc.)
  • Determination of the elemental composition (O: C, H: C)

The instrument is transportable and can be placed on vans but also on small aerial platforms. Having high acquisition speeds it is possible to carry out a high resolution mapping even on airliners.

Through the acquisition of vertical profiles it is possible to study the correlations between the chemical composition of the aerosol and the optical properties of the particulate.

For example, it has already been observed that the humidity present on the particulates greatly influences the optical properties and the AMS is able to instantly determine not only the content in water but also of other chemical species, so as to give information on hygroscopicity of the particulate matter. In this way it is possible to calibrate the images from satellite or in general from remote sensing to improve the information that these images can give about the chemical composition.

Furthermore, the AMS, in laboratory tests, can evaluate the kinetics of secondary particulate formation and adsorption phenomena of chemical species on atmospheric particulate.