Aerosol spectrometry in the infrared

Aerosol spectrometry denotes a methodology for describing spectral effects of atmospheric constituents in quantitative, standardized, basic terms. It is based on the premise that most atmospheric constituents can be described (albeit in some cases very unconventionally) as specialized kinds of aerosols, some of which exhibit complex changes in spectral behavior between physical phases. Aerosol spectrometry permits an intuitive understanding of the spectral properties of atmospheric constituents and, very important, allows insights to be gained not found in traditional or purely mathematical treatments. The discussion includes liquid and solid particulate aerosols, special cases including Christiansen effects and isosbestics, and the phase-transitional behavior of liquid droplets in vapor. A study of the latter led to the finding that anomalous (continuum) IR absorption in water vapor could be attributed to liquidlike intermolecular hydrogen bonds in molecular complexes (clusters) long before this observation was made using traditional vapor spectrometric techniques.