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The air is often thought to be benign and, of course, we need it to breathe. However, on an atomic scale and under certain conditions, the air can be damaging. Electrochemical reactions can be susceptible to trace contamination and electrochemistry experiments often require atomically ordered electrode surfaces. Oxygen in the air can destroy atomic order and contaminate electrodes through the formation of oxides. The image shows a platinum single crystal being annealed using a hydrogen flame, which reorders the surface atoms and decomposes contaminants. Hydrogen flames are often used when cleanliness is important, as they leave no residues.