Leibniz-Institut für Troposphärenforschung e.V., Leipzig 04318, Germany.
Science. 2010 Mar 5;327(5970):1243-6. doi: 10.1126/science.1180315.
Nucleation is a fundamental step in atmospheric new-particle formation. However, laboratory experiments on nucleation have systematically failed to demonstrate sulfuric acid particle formation rates as high as those necessary to account for ambient atmospheric concentrations, and the role of sulfuric acid in atmospheric nucleation has remained a mystery. Here, we report measurements of new particles (with diameters of approximately 1.5 nanometers) observed immediately after their formation at atmospherically relevant sulfuric acid concentrations. Furthermore, we show that correlations between measured nucleation rates and sulfuric acid concentrations suggest that freshly formed particles contain one to two sulfuric acid molecules, a number consistent with assumptions that are based on atmospheric observations. Incorporation of these findings into global models should improve the understanding of the impact of secondary particle formation on climate.
成核是大气中新粒子形成的基本步骤。然而，实验室中成核的实验未能系统地证明硫酸粒子形成的速率足以解释环境大气浓度，并且硫酸在大气成核中的作用仍然是一个谜。在这里，我们报告了在与大气相关的硫酸浓度下立即观察到新粒子（直径约为 1.5 纳米）形成后的测量结果。此外，我们表明，测量的成核速率与硫酸浓度之间的相关性表明，新形成的粒子含有一到两个硫酸分子，这与基于大气观测的假设一致。将这些发现纳入全球模型中，应该可以提高对二次粒子形成对气候影响的理解。
