In-situ FTIR-ATR spectroscopic observation on the dynamic efflorescence/deliquescence processes of Na₂SO₄ and mixed Na₂SO₄/glycerol droplets

The FTIR-ATR spectra of Na₂SO₄ and mixed Na ₂SO₄/glycerol (1:1) aerosols are monitored in the dehumidifying and humidifying process. It shows that glycerol suppresses both heterogeneous and homogeneous nucleation of Na₂SO₄/ glycerol aerosols on the ZnSe substrate, while the water uptake of surrounding glycerol leads to lower deliquescence relative humidity of mixed Na ₂SO₄/glycerol aerosols. In mixed Na₂SO ₄/glycerol aerosols, glycerol restrains the formation of contact ion pairs between Na⁺ and SO₄^2-, resulting in the delay of the efflorescence relative humidity. And glycerol molecular conformations transform from γγ to αα type in the dehumidifying process.