Characterising the silver particle generator; a pathway towards standardising silver aerosol generation. (June 2022)

• Record Type: Journal Article
• Authors: Hammer, T.; Irwin, M.; Swanson, J.; Berger, V.; Sonkamble, U.; Boies, A.; Schulz, H.; Vasilatou, K.
• Is Part Of: Journal of aerosol science. Volume 163(2022)
• Publication Date: 2022-06
• Subjects: silver particle generator -- Aerosol calibration -- Reference aerosol -- CPC calibration -- DMA calibration; Aerosols -- Periodicals; Aerosols -- Periodicals; Aérosols -- Périodiques; 541.34515
• DOI: 10.1016/j.jaerosci.2022.105978
• Languages: English
• ISSNs: 0021-8502

Abstract

Abstract: Reference aerosols for the calibration of common aerosol instruments such as condensation particle counters (CPCs) and differential mobility analyzers (DMAs), must fulfill certain criteria. The aerosol must be stable and reproducible in particle size and number density, ideally be monodisperse and nonvolatile and comprise a uniform non-reactive material. To this end, a new Silver Particle Generator (SPG) from Catalytic Instruments (Catalytic Instruments, Rosenheim, Germany) was characterized extensively with regard to aerosol properties within an overall framework of operator convenience. The SPG produced number densities up to around 2 × 10 10 cm −3 of thermally stable, solid, unimodal aerosol with geometric standard deviation smaller than 1.45. The aerosol production in the SPG resembles that of a classic tube furnace, however, the device is easier to set up and configure, and offers long-term stability using controlled standardized procedures and operation settings. The SPG has two operational modes (simply, Modes 1 & 2 for the smallest and largest aerosol, respectively). The aerosol exhibited an intraday stability and day-to-day reproducibility in geometric mean mobility diameter ( GMD mob ) within a standard deviation of 4%. Based on measurements by transmission electron microscopy (TEM), particles from Mode 1 were spherical when default settings (air as carrier/dilution gas) were applied, whereas larger particles from Mode 2 comprised both compact near-spherical particles, and larger aggregates. Switching to nitrogen as a carrier gas and sintering at 800 °C reshaped the aggregate fraction of the aerosol from Mode 2 into uniformly spherical particles. Suitable applications of the SPG include the calibration of CPCs, DMAs, particle measurement program (PMP)-compliant measurement including particle number counters (PNCs) and the characterization of complete particle number - portable emissions measurement systems (PN-PEMS) systems and other particle counters for air quality monitoring. Graphical abstract: Image 1 Highlights: The silver particle generator produces particles with mobility diameter in the range <5 nm–70 nm. The aerosols exhibited a day-to-day reproducibility in particle size within 4%. Concentrations up to 1.78 × 10 cm −3 of thermally stable, solid, monodisperse aerosols The silver particle generator is suitable for the calibration of CPCs, DMAs, and other devices