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阶梯状改变环境湿度,利用FTIR-ATR(Attenuated Total Reflection)技术以及显微成像技术观察NaNO3气溶胶微粒的结晶动力学。多次实验证实NaNO3液滴在饱和点74.5%RH之后开始陆续风化,至风化点53%RH之后结晶速率明显增快,但并不是相对湿度越低,结晶速率越快,而是相对湿度的变化率越大,结晶速率越快。对数据进行非线性拟合发现在湿度下降处结晶速率呈指数关系,在湿度稳定時结晶速率呈线性关系。并且通过显微镜观察到尽管样品NaNO3液滴的直径在同一个数量级上,仍能看出结晶速率与液滴半径关系紧密,半径越大越易结晶,结晶的相对湿度越高。
Stepwise changes in environmental humidity, the use of FTIR-ATR (Attenuated Total Reflection) technology and microscopic imaging techniques observed NaNO3 aerosol particle crystallization kinetics. Several experiments confirmed that NaNO3 droplets began to weather after saturation point 74.5% RH. The crystallization rate increased obviously after weathered point 53% RH, but not the lower the relative humidity, the faster the crystallization rate, but the change of relative humidity The greater the rate, the faster the crystallization rate. Non-linear fitting of the data revealed an exponential relationship between the rate of crystallization at the descending humidity and a linear relationship between the rate of crystallization at the steady-state humidity. And it is observed by microscope that although the diameter of the sample NaNO3 droplets is on the same order of magnitude, it can be seen that the crystallization rate is closely related to the droplet radius. The larger the radius, the more easily the crystal is crystallized, and the higher the relative humidity of the crystal is.