Solid, Semisolid, and Liquid Phase States of Individual Submicrometer Particles Directly Probed Using Atomic Force Microscopy,Analytical Chemistry

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Solid, Semisolid, and Liquid Phase States of Individual Submicrometer Particles Directly Probed Using Atomic Force Microscopy
Analytical Chemistry ( IF 6.7 ) Pub Date : 2017-11-22 00:00:00 , DOI: 10.1021/acs.analchem.7b02755
Hansol D. Lee ₁ , Kamal K. Ray ₁ , Alexei V. Tivanski ₁

Affiliation

Currently, the impact of various phase states of aerosols on the climate is not well understood, especially for submicrometer sized aerosol particles that typically have extended lifetime in the atmosphere. This is largely due to the inherent size limitations present in current experimental techniques that aim to directly assess the phase states of fine aerosol particles. Herein we present a technique that uses atomic force microscopy to probe directly for the phase states of individual, submicrometer particles by using nanoindentation and nano-Wilhelmy methodologies as a function of relative humidity (RH) and ambient temperature conditions. When using these methodologies for substrate deposited individual sucrose particles, Young’s modulus and surface tension can be quantified as a function of RH. We show that the force profiles collected to measure Young’s modulus and surface tension can also provide both qualitative and quantitative assessments of phase states that accompany solid, semisolid, and liquid particle phases. Specifically, we introduce direct measurements of relative indentation depth and viscoelastic response distance on a single particle basis at a given applied force to quantitatively probe for the phase state as a function of RH and corresponding viscosity. Thus, we show that the three phase states and phase state transitions of sucrose can be identified and ultimately propose that this technique may also be used to study other atmospherically relevant systems.

中文翻译：

使用原子力显微镜直接探测单个亚微米颗粒的固态，半固态和液相状态

当前，关于气溶胶的各种相态的影响尚不十分清楚，特别是对于通常在大气中具有较长使用寿命的亚微米级气溶胶颗粒而言。这很大程度上是由于目前旨在直接评估细小气溶胶颗粒相态的实验技术中存在的固有尺寸限制。本文中，我们介绍了一种利用原子力显微镜技术通过相对于相对湿度（RH）和环境温度条件使用纳米压痕和纳米威勒密方法直接探测单个亚微米颗粒的相态的技术。当将这些方法用于底物沉积的单个蔗糖颗粒时，杨氏模量和表面张力可以作为RH的函数进行量化。我们表明，收集用来测量杨氏模量和表面张力的力曲线还可以提供对固相，半固相和液相相的相态的定性和定量评估。具体而言，我们在给定的作用力下，直接测量相对压痕深度和粘弹性响应距离（基于单个粒子），以定量探测作为RH和相应粘度的函数的相态。因此，我们表明可以识别蔗糖的三个相态和相态转变，并最终提出该技术也可以用于研究其他与大气有关的系统。和液相颗粒相。具体而言，我们在给定的作用力下，直接测量相对压痕深度和粘弹性响应距离（基于单个粒子），以定量探测作为RH和相应粘度的函数的相态。因此，我们表明可以识别蔗糖的三个相态和相态转变，并最终提出该技术也可以用于研究其他与大气有关的系统。和液相颗粒相。具体而言，我们在给定的作用力下，直接测量相对压痕深度和粘弹性响应距离（基于单个粒子），以定量探测作为RH和相应粘度的函数的相态。因此，我们表明可以识别蔗糖的三个相态和相态转变，并最终提出该技术也可以用于研究其他与大气有关的系统。

更新日期：2017-11-23

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