Preprints
https://doi.org/10.5194/acp-2021-763
https://doi.org/10.5194/acp-2021-763

  15 Nov 2021

15 Nov 2021

Review status: this preprint is currently under review for the journal ACP.

Technical Note: Real-Time Diagnosis of the Hygroscopic Growth Micro-Dynamics of Nanoparticles with Two-Dimensional Correlation Infrared Spectroscopy

Xiuli Wei1,2, Haosheng Dai1,2, Huaqiao Gui1,3, Jiaoshi Zhang1, Yin Cheng1,2, Jie Wang1, Yixin Yang1, Youwen Sun1, and Jianguo Liu1,2,3 Xiuli Wei et al.
  • 1Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
  • 2University of Science and Technology of China, Hefei 230031, China
  • 3CAS Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China

Abstract. Nanoparticles can absorb water to grow up and this will affect the light scattering behavior, cloud condensation nuclei properties, lifetime, and chemical reactivity of these particles. Current techniques usually assume the shapes of nanoparticles to be spherical in calculation of aerosol liquid water content (ALWC), which may result in large uncertainties when the shapes of nanoparticles show large deviations to the spherical assumptions. Furthermore, current techniques are also difficult to identify the intermolecular chemical interactions of phase transition micro-dynamics during nanoparticle deliquescence process because their limited temporal resolutions are unable to capture the complex femtosecond-level intermediate states. In this study, the hygroscopic growth properties of nanoparticles with electrical mobility diameter of approximately 100 nm and their phase transition interaction dynamics on molecular scale are characterized on real time by using the Fourier transform infrared (FTIR) and the two-dimensional correlation infrared (2D-IR) spectroscopic techniques. With the FTIR spectroscopy, we develop a novel real-time method for ALWC by constructing the absorption spectra of liquid water, and realized real-time measurements of water content and dry nanoparticle mass to characterize the hygroscopic growth factors (GF) which show discrepancies to the extended aerosol inorganics model (E-AIM). We further explore the difference that the deliquescence points of sodium nitrate (SN) and oxalic acid (OA) compounds are lower than that of AS by using the 2D-IR spectroscopic analysis technique. We also identify the occurrence sequential order of the hydration interactions and investigate the dynamic deliquescence process of the functional groups for AS and its mixture compounds. Both SN and OA compounds lower the deliquescence point of AS, but only AN can change the hydrolysis reaction mechanism for AS in AS/AN and AS/OA mixtures. This study can not only provide important information with respect to the difference in phase transition point under different conditions, but also improve current understanding of the chemical interaction mechanism between nanoparticles (particularly for organic particles) and medium, which is of great significance for haze control across China.

Xiuli Wei et al.

Status: open (until 27 Dec 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2021-763', Anonymous Referee #2, 29 Nov 2021 reply

Xiuli Wei et al.

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Short summary
We develop a novel real-time method for ALWC by constructing the absorption spectra of liquid water, characterize the hygroscopic growth factors (GF), and investigate the dynamic deliquescence process of the functional groups for AS and its mixture compounds. This study could improve current understanding of the chemical interaction mechanism between nanoparticles (particularly for organic particles) and medium, which is of great significance for haze control across China.
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