Preprints
https://doi.org/10.5194/egusphere-2023-1346
https://doi.org/10.5194/egusphere-2023-1346
12 Jul 2023
 | 12 Jul 2023

Measurement Report: Water diffusion in single suspended phase-separated aerosols

Yu-Kai Tong, Zhijun Wu, Min Hu, and Anpei Ye

Abstract. Water diffusion is a typical thermodynamic process in ambient aerosols which plays pivotal roles in their physicochemical properties, atmospheric lifetime, and influences on the climate and human health. A fair amount of aerosols become phase-separated after experiencing atmospheric aging processes such as efflorescence, amorphization, and liquid-liquid phase separation. However, detecting the hygroscopicity of heterogeneous aerosols is quite intractable. Here, for the first time, we directly characterize the water diffusion in single suspended phase-separated aerosols via a self-constructed laser tweezers Raman spectroscopy (LTRS) system. The H2O/D2O isotope exchange is harnessed to trace the water diffusion in single laser-levitated homogenous/heterogeneous microdroplets. The time-resolved cavity-enhanced Raman spectra of the microdroplets is used to detect the diffusion process in real time. Two archetypes of phase-separated aerosols, i.e., partially engulfed and core-shell, are studied. Moreover, we quantify the dynamic water diffusion process by experimentally measuring the diffusion coefficients. The results show that compared with the homogenous aerosols, water diffusion limitations exist in the phase-separated aerosols. The incomplete diffusion may stem from both the hydrophobicity of the organics and the formation of certain molecule clusters. This work provides possible implications on the evolutions, especially the gas-particle partition, of the actual phase-separated atmospheric aerosols.

Yu-Kai Tong et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1346', Anonymous Referee #1, 23 Jul 2023
    • AC1: 'Reply on RC1', Yu-Kai Tong, 23 Aug 2023
  • RC2: 'Comment on egusphere-2023-1346', Anonymous Referee #2, 28 Jul 2023
    • AC2: 'Reply on RC2', Yu-Kai Tong, 23 Aug 2023

Yu-Kai Tong et al.

Data sets

Dataset for “Measurement Report: Water diffusion in single suspended phase-separated aerosols” Yu-Kai Tong, Zhijun Wu, Min Hu, and Anpei Ye https://doi.org/10.18170/DVN/LJMWYV

Yu-Kai Tong et al.

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Short summary
The interplay between aerosols and moisture is one of the most crucial atmospheric processes. However, till date, the literature results on the influence of phase separation on water diffusion in aerosols are divergent. This work directly unveiled the water diffusion process in single suspended phase-separated microdroplets and quantitatively analyzed the diffusion rate and extent. The results show that diffusion limitations and certain molecule clusters exist in the phase-separated aerosols.