Description:
<jats:p>The combination of a large aerosol chamber and a recently developed Aerosol Composition Mass Spectrometer (ACMS) was used to investigate sulfuric acid aerosols at low temperatures. Concentrations of condensed phase H<jats:sub>2</jats:sub>SO<jats:sub>4</jats:sub> and H<jats:sub>2</jats:sub>O were determined with an accuracy of better than 4 wt.%. Simultaneous measurements of temperature, partial pressure of water, total sulfate amount and particle size distribution permit to calculate the particle equilibrium composition. The model description of <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#grl14838-bib-0003"><jats:italic>Carslaw et al.</jats:italic> [1995a]</jats:ext-link> for H<jats:sub>2</jats:sub>SO<jats:sub>4</jats:sub>/H<jats:sub>2</jats:sub>O solutions was confirmed in the composition range from 35 to 68 wt.% H<jats:sub>2</jats:sub>SO<jats:sub>4</jats:sub> for temperatures between 188 and 236 K, extending the experimental verification to lower temperatures. Although the sub‐micron particles were up to 25 K super‐cooled with respect to solid sulfuric acid hydrates such as the tetrahydrate (SAT), they remained liquid for days.</jats:p>