A study of phase transformations in hygroscopic aerosols by Raman spectroscopy
- Brookhaven National Lab., Upton, NY (United States)
Atmospheric aerosol particles are composed mostly of hygroscopic inorganic salts. These aerosols play an important role in many atmospheric processes which affect local air quality, visibility degradation, and the global climate as well. Indeed, hygroscopic aerosols as metastable supersaturated solution droplets are routinely observed in laboratories. Here, we report first spectroscopic evidence that new metastable solid states form from hygroscopic aerosol particles. Levitated single particles undergo hydration and crystallization in calibrated humidity environment. Laser Raman and Mie scattering techniques are used to probe the chemical and physical state of the microparticle before and after phase transformation. The formation of these states is not predicted from bulk-phase thermodynamics. In some cases, the resulting metastable state is entirely unknown heretofore. We also present new solid/solution and solid/solid phase transitions which occur exclusively in microparticles.
- OSTI ID:
- 214625
- Report Number(s):
- CONF-950801--
- Country of Publication:
- United States
- Language:
- English
Similar Records
Phase transformation and growth of hygroscopic aerosols
Hydration and Raman scattering studies of levitated microparticles: Ba(NO{sub 3}){sub 2}, Sr(NO{sub 3}){sub 2}, and Ca(NO{sub 3}){sub 2}