| abstract |
The presence of an aerosol or cloud ( 3 ) of a toxic substance is detected by producing an aerosol ( 17, 5 ) of ligands ( 13 ) to the target substance in a region of sky that contains the target substance, permitting molecules the target substance to bind to the ligand, directing light ( 7, 21 ) of a first frequency into the revised aerosol; and then inspecting ( 9, 25 ) the revised aerosol for emissions of light of a second frequency. When light of the second frequency exists an alarm ( 15, 31 ) is initiated. |