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

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