Author: Maria Temming / Source: Science News
Oil and water may not mix, but the two have now revealed a new example of structural color, in which an object’s hue arises from its shape.
Studying droplets made of two layers of clear oil, researchers discovered that, depending on a viewer’s perspective, the tiny blobs glowed a variety of vibrant colors under white light. In a petri dish, same-sized droplets changed color as the dish was rotated (see video below). The same phenomenon, described in the Feb. 28 Nature, occurred with tiny water droplets that collected on the underside of a petri dish’s lid.
Materials chemist Lauren Zarzar of Penn State and colleagues found that the iridescent hues appear when light strikes a bowl-shaped boundary between two substances — in this case, the water-air barrier on the underside of the water droplets hanging off a flat surface, or a basin-shaped divide between the two layers of oil. Light that enters near a droplet’s edge bounces along this this concave surface multiple times before…
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