%A %T Measurement on Mass Growth Factors of (NH4)2SO4, NH4NO3, and Mixed (NH4)2SO4/NH4NO3 Aerosols Under Linear RH Changing Mode %0 Journal Article %D 2021 %J SPECTROSCOPY AND SPECTRAL ANALYSIS %R 10.3964/j.issn.1000-0593(2021)11-3444-07 %P 3444-3450 %V 41 %N 11 %U {https://www.gpxygpfx.com/CN/abstract/article_12316.shtml} %8 2021-11-01 %X The hygroscopicity of aerosol particles determines their size, concentration, chemical compositions and phase states, and thus affects the global climate, heterogeneous atmospheric chemistry and human health. In this study, an on-line and in-situ rapid scan attenuated total reflection Fourier transform infrared (ATR-FTIR) technique coupled with a linear relative humidity (RH) controlling system was utilized to obtain the IR spectra of aerosols under different RH. The mass growth factors (MGFs), deliquescence relative humidity (DRH) and efflorescence relative humidity (ERH) of (NH4)2SO4, NH4NO3, and mixed (NH4)2SO4/NH4NO3 aerosols were determined rapidly by measuring the peak areas of the bending vibration band of liquid water (~1 640 cm-1). Comparisons between the measurements and the predictions from the E-AIM model showed good consistency, which verifies the rapid scan ATR-FTIR as a powerful tool for investigating hygroscopic behaviors and phase transitions of atmospheric aerosols. Furthermore, pure (NH4)2SO4 and NH4NO3 particles were found to effloresce at 49% and 25% RH, respectively, while mixed (NH4)2SO4/NH4NO3 aerosols with a mole ratio of 1∶1 and 1∶2 exhibited one-stage efflorescence transition beginning at 44% and 38% RH, respectively, upon dehydration. These results indicate that the presence of NH4NO3 can inhibit the crystallization of (NH4)2SO4, and formed (NH4)2SO4 seeds will act as heterogeneous nuclei to promote the efflorescence of NH4NO3 at higher RH. In addition, the double salt (NH4)2SO4·2NH4NO3 was formed upon efflorescence of mixed particles. These findings are critical for understanding complex phase transitions of mixed inorganic aerosols and interpretation for RH dependency of heterogeneous reaction rates of atmospheric reactive species.