The (220) lattice spacing of silicon

Further details are given of an experiment based on combined X-ray and optical interferometry to measure the (220) lattice spacing of silicon. A resolution of 5/spl times/10/sup -9/ d/sub 220/ was achieved and the silicon d/sub 220/ was determined to 3/spl times/10/sup -8/ d/sub 220/ accuracy. The measured value is d/sub 220/=(192015.551/spl plusmn/0.005) fm. After correction for the impurity-induced lattice strain, d/sub 220/=(192015.569/spl plusmn/0.006) fm was obtained.<
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