KnowraHyperfine structureLinked fromLinked fromThe 17 pages that link to Hyperfine structure, each with the reason it gives.All 17Broader topic 3Related 10Narrower topic 2Compared with 221-centimeter lineNarrower topic: The line is a specific hyperfine splitting in the hydrogen ground state.Neutral hydrogenNarrower topic: The line is a hyperfine transition between two relative orientations of electron and proton spins.