Behind every colour lies exact science – the arrangement of atoms, molecular bonds, light spectra – and it is precisely at this point, between molecules and colours, that materials science and new innovations develop. In anticipation of Researchers' Night, researchers at the Institute of Solid State Physics, University of Latvia (ISSP UL) share stories about the interaction of colour and science in our daily work and laboratory experiments.
Gemstones adorn the crowns of monarchs, serve as bearings in watch movements, and are used in scientific research and advanced technological devices. But what gives them their unique properties and dazzling colours? Spectroscopy Laboratory researcher Rihards Ruska explains.
“Many gemstones are based on surprisingly ordinary compounds, such as aluminium oxide (the material on aluminium foil) or various silicates (found on any beach). They form deep within the Earth's crust, where heat and immense pressure over millions of years allow these compounds to crystallize into highly ordered structures, forming beautiful crystals. In their completely pure form, the resulting crystals are usually transparent and colourless.”
“So why is a ruby red, for example, while a sapphire is blue, even though both are made from the exact same compound – aluminium oxide? The secret lies in small chemical variations and crystal lattice defects. Just a few chromium atoms among the thousand other atoms can transform a transparent aluminium oxide crystal into a vivid red ruby. Why? The presence of these atoms changes how the crystal absorbs visible light. In spectroscopy, we use this phenomenon as an analytical tool.” Rihards Ruska explains.
By illuminating a material with light and studying its absorption spectrum, ISSP UL scientists can determine its chemical composition with extreme precision. A similar approach makes it possible, for example, to analyse plasma-facing wall materials in Europe's upcoming ITER nuclear fusion reactor to ensure that no foreign atoms have entered the material and that the walls have not begun to crack.
Discover more colourful wonders of science in the article series Between Molecules and Colors!
