Chemistry In Pictures

Quinton Meisner, a chemist at Florida State University, shot this photo looking down the barrel of a vial at crystals of a boron-dipyrromethene (BODIPY) azide. He excited the crystals with ultraviolet light, and the resulting orange glow traveled up the sides of the glass to create an image reminiscent of the gun barrel sequence seen during the opening of James Bond movies. This BODIPY compound is a synthetic intermediate en route to a molecule that could detect metal ions or other chemicals found in neurons or groundwater. The final sensor will stop glowing in the presence of the target molecules.—Craig BettenhausenSubmitted by Quinton Meisner and Lei Zhu of Florida State University

The flaws in this andradite garnet gemstone [Ca3Fe2(SiO4)3] produce its mesmerizing colors. Some gemologists think that this rainbow explosion arises because the garnet’s different elements aren’t regularly spaced from the core of the gemstone to the outside. For example, in some regions, aluminum atoms might have worked their way into the structure and replaced the iron atoms. These irregularities create mismatched sheets of atoms that then bend and stretch. This makes the stone birefringent, meaning that light travels through it at two different speeds. Under cross-polarized lighting conditions, rays of light that enter get misaligned by the time they exit, so they then interfere with each other and highlight some colors in certain spots, producing the spectrum seen here. The black flecks are tiny pieces of magnetite that were enveloped by the crystal as it grew.—Manny Morone