How Diamonds and Light Measure Immense Pressure ⚡ экспресс
We present a wide-field optical microscopy method for mapping pressure distribution in a diamond anvil cell at pressures around 20 GPa. Nitrogen-vacancy centers in nanodiamonds serve as quantum sensors. By analyzing spectra of optically detected magnetic resonance with models that incorporate hydrostatic and uniaxial stress components, we obtain maps of pressure and the degree of non-hydrostaticity. A comparison of two methods for introducing nanodiamonds into the pressure-transmitting medium shows that the embedding technique affects stress inhomogeneity. This approach provides a powerful platform for visualizing pressure-driven phenomena and can be extended to probe other physical parameters, such as magnetic fields.
Inside a diamond anvil cell—a chamber where two diamond pyramids crush a tiny droplet of liquid with forces generating pressures as high as at Earth's center—scientists sprinkled diamond dust of carbon. Each virus-sized grain, under a laser beam, began to glow like a microscopic lightbulb, and its light changed depending on how strongly the surrounding liquid was compressed: higher pressure shifted the color and increased brightness.
Collecting light from millions of these twinkling particles and analyzing it using spectroscopy (splitting it into a spectrum) and photometry (measuring brightness), researchers for the first time saw not just an average number but a vivid landscape of unevenness. Pressure spread in patches, like a heat map: they discovered 'hot spots' where compression was significantly higher, threatening the sample's integrity. Previously, such anomalies could only be guessed at.
In the future, this method will not only control high-pressure experiments but also study magnetic fields or model the interiors of distant planets. A striking fact: diamond dust specks, withstanding a monstrous 200,000 atmospheres (at which steel flows like water), act as ideal, indestructible sensors. They register pressure fluctuations of just a few tens of atmospheres, remaining stable beacons in this extreme hell.
🎯 A pressure of 20 gigapascals (roughly 200,000 atmospheres) can turn soft graphite into diamond—exactly the conditions created in diamond anvil cells.