Experimental evidence for internal structure in aqueous-organic nanodroplets

Area of Science:

• Atmospheric chemistry
• Physical chemistry
• Nanotechnology

Background:

• The spatial arrangement of components within aerosol droplets affects their environmental interactions.
• Multicomponent nanodroplets are prevalent in aerosols but their internal structures remain uncharacterized.

Purpose of the Study:

• To experimentally determine the internal structure of aqueous organic nanodroplets.
• To provide the first measurements of nanodroplet internal composition and spatial distribution.

Main Methods:

• Utilized small angle neutron scattering (SANS).
• Analyzed high number density aerosols of aqueous organic nanodroplets.
• Fitted diffraction patterns to model droplet structure.

Main Results:

• Successfully measured the internal structure of H(2)O-n-butanol nanodroplets.
• Confirmed a core-shell structure: an aqueous core with ~3 mol% n-butanol.
• Observed a densely packed n-butanol molecular shell surrounding the aqueous core.

Conclusions:

• The study provides the first experimental evidence of internal structure in aqueous organic nanodroplets.
• The findings reveal a distinct phase separation and molecular organization within these nanodroplets.
• This structural understanding is crucial for predicting aerosol behavior and environmental impact.