Primary Study on the Atmospheric Reactions Involving Ice Particles

1）设计并构造了差动泵送的双室装置，其中引入冰粒或水滴，并使其在与热膜风速计的探针碰撞时蒸发，用于蒸汽的质量分析。确定了入口孔的尺寸和泵送速度，以优化颗粒和蒸汽的引入效率。2）通过使用引入到3托压力中的冰粒来检查风速计在减压下的性能。据发现，只有通过降低一半的热膜电压的颗粒尺寸是可能的。然而，在减压下测量的尺寸分布与在大气压下观察到的不同。经过几次测试实验，得出的结论是，颗粒入口的形状是获得准确的尺寸分布的关键。3）为了区分来自蒸汽的质量信号和来自背景气体的质量信号，构造了一个触发电路，该触发电路与颗粒与热膜的碰撞同步地启动质量分析器的时间扫描。利用该装置观察到，水滴与热膜碰撞后15 ms时，H_2O^+信号达到峰值。4）碳酸铵和亚硫酸盐在溶液中不挥发，但加热时会产生气态分解产物。利用这一事实，在含有这些物质的液滴上进行了PEMS实验，结果观察到了来自分解产物的微弱信号。因此，PEMS原则上可用于研究涉及液滴或冰粒的化学反应。

1)A differentially pumped two-chamber apparatus was designed and constructed into which ice particles or water droplets were introduced and made to evaporate in collision with a probe of a hot-film anemometer for the mass-analysis of the vapor. The sizes of the inlet apertures and the pumping velocities were determined so as to optimize the particle- and the vapor-introduction efficiency.2)The performance of the anemometer under the reduced pressure was examined by using ice particles introduced into a pressure of 3 Torr. It was found that the particle sizing was possible only by lowering the hot-film voltage by half. However the size distribution measured under the reduced pressure was different from that observed in the atmospheric pressure. After several test experiments it was concluded that the shape of the particle inlet was critical for obtaining an accurate size distribution.3)In order to discriminate between the mass-signals from the vapor and those from the background gas, a triggering circuit was constructed that started the time-sweep of the mass analyzer synchronously with the collision of the particle with the hotfilm. By means of this device, it was observed that H_2O^+ signal from water droplets came to a peak at 15 ms after the collision with the hot-film. Consequently the basic feasibility of an entirely new method of "Particle Evaporation Mass Spectrometry (PEMS)" was proved.4)Ammonium carbonate and sulfite in solution are non-volatile, but they produce gaseous decomposition products when heated. Taking advantage of this fact, PEMS experiments were tried on the droplets containing those substances, resulting in the observation of weak signals from the decomposition products. PEMS was thus shown to be usable, in principle, for investigating chemical reactions involving droplets or ice particles.