Hyperfine Structure Calculator
Calculate hyperfine splitting from electron-nucleus spin interaction
Hyperfine Structure: Hydrogen 1s
Quantum Numbers
J = 0.5, I = 0.5
Hyperfine Constant A
1420.405752 MHz
Total Hyperfine Splitting
1420.405752 MHz
Wavelength: 21.1066 cm
Hyperfine Levels (F = |J-I| to J+I)
F = 0: E = -1065.3043 MHz, degeneracy = 1
F = 1: E = 355.1014 MHz, degeneracy = 3
Number of Hyperfine Levels
2
Formulas Used
E_hfs = (A/2) * K
K = F(F+1) - I(I+1) - J(J+1)
F = |J-I|, |J-I|+1, ..., J+I
Hydrogen 21 cm line: 1420.405751768 MHz
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Editorial Note
MyCalcBuddy Editorial Team
This page is maintained as an educational calculator reference.
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Formula Source: University Physics
by Young & Freedman
🔄Last reviewed: May 2026
✓Formula checks are based on standard references and internal QA review.