We study the structural properties of dodecyltrimethylammonium bromide (DTAB) micelles and micro-emulsions by probing the molecular reorientation of water with polarization-resolved infrared pump-probe spectroscopy. For all systems studied, we observe that a fraction of water reorients on a much slower timescale than bulk water. This slow water fraction increases sublinear with increasing DTAB concentration, indicating an increase of the micelle size and enhanced micelle aggregation with concentration. We observe that the addition of oil to the micelle solutions, leading to the formation of a micro-emulsion, does not lead to a significant change of the fraction of slow water, showing that the added oil molecules are well solvated within the core of the micelles, and thus completely shielded from water.

我们通过用偏振分辨红外泵浦探针光谱探测水的分子取向来研究十二烷基三甲基溴化铵（DTAB）胶束和微乳液的结构特性。对于所有研究的系统，我们观察到一部分水的重新定向时间要比散装水慢得多。随着DTAB浓度的增加，这种缓慢的水分数增加了亚线性，表明随着浓度的增加，胶束的大小增加，胶束聚集增强。我们观察到，向胶束溶液中添加油会导致形成微乳状液，不会导致慢水的比例发生显着变化，这表明所添加的油分子在硅油的核心内已被很好地溶剂化。胶束，因此完全被水屏蔽。