Fig. 1. Condensation experiment platform based on ATR: (a) The single attenuated total; (b) a schematic of the ATR accessory integrated with cooled surface.ATR技术检测团簇的原理　(a) 单点衰减全反射; (b) 在ATR附件上的冷凝平台

Fig. 2. Schematic diagram of experimental setup. 1, temperature control furnace; 2, copper heat pipe; 3, three-dimensional displacement platform; 4, condensing chamber; 5, ATR accessory; 6, computer; 7, scrubber; 8, flow meter; 9, nitrogen cylinder.实验装置示意图(1, 控温炉; 2, 热管; 3, 三维位移平台; 4, 冷凝腔室; 5, ATR附件; 6, 电脑; 7, 洗气瓶; 8, 流量计; 9, 氮气瓶)

Fig. 3. Infrared spectra of saturated vapor of water condensing near the cooling surface: (a) The absorption spectra at each distance, d = 1700−0 μm from bottom to top; (b) the frequency of maximum intensity in OH bonded stretching region of each spectrum, peak 1 is red-shifted by about 14 cm^–1, peak 2 is red-shifted by about 5.8 cm^–1; (c) the peak high and the relative intensity of the peak 1 and peak 2 as a function of distance. 饱和水蒸气在近壁面冷凝的红外光谱　(a) 各位置处的吸收光谱, 各谱线由下而上依次为d = 1700−0 μm; (b) 各吸收光谱的频率, peak 1红移14 cm^–1, peak 2红移5.8 cm^–1; (c) 各位置处吸收光谱的峰高及两者的相对强度随距离的变化

Fig. 4. Infrared spectra of saturated vapor of ethanol condensing near the cooled surface: (a) The absorption spectra at each distance, d = 2000−0 μm from bottom to top; (b) the frequency of maximum intensity in bonded OH stretching region of each ATR-FTIR spectrum ofFig. 4(a). 饱和乙醇蒸气在近壁面冷凝的红外光谱　(a) 距壁面不同距离的气相的红外光谱, 各谱线自下而上依次为d = 2000−0 μm; (b) 各距离处的ATR-FTIR光谱的频率