Reduced Compton wavelength
Atomic & nuclearMeasured
= 3.861 592 6744(12) × 10−13 m
- Value
- 3.861 592 6744 × 10−13 m
- Standard uncertainty
- 1.2 × 10−22 m
- Relative uncertainty
- 3.1 × 10−10 (311 parts per trillion)
- Status
- Measured
- Symbol
- Source
- CODATA 2022 via NIST · NIST entry
Use in a calculation
# reduced Compton wavelength, CODATA 2022 (NIST)
reduced_compton_wavelength = 3.8615926744e-13 # m, standard uncertainty 1.2e-22
# SciPy: scipy.constants.physical_constants['reduced Compton wavelength']What it is
The electron Compton wavelength divided by 2π, ħ/(mₑc). It is the natural unit of length in relativistic quantum mechanics.
In other units
| Unit | Value | |
|---|---|---|
| CGS (cm) | 3.861 592 6744 × 10−11 | |
| pm picometre | 0.386 159 267 44 | |
| fm femtometre | 386.159 267 44 | |
| Å ångström | 0.003 861 592 6744 | |
| a₀ bohr (atomic unit) | 0.007 297 352 564 | unit is itself measured |
Converted with ConstantID's unit table; digits are rounded to the precision of the value, and a long exact value is rounded only for display. The relative uncertainty is unchanged by conversion to an exactly defined unit.
How the value changed, 1998–2022
Each point is one CODATA adjustment, plotted as its difference from the 2022 value; the bars show one standard uncertainty (an arrowhead means the bar runs off the chart).
Relative uncertainty
| CODATA | Value (uncertainty) | Relative uncertainty | Change from previous |
|---|---|---|---|
| 2022 | 3.861 592 6744(12) × 10−13 | 3.1 × 10−10 | −4.3 σ of 2018 |
| 2018 | 3.861 592 6796(12) × 10−13 | 3.1 × 10−10 | +1.8 σ of 2014 |
| 2014 | 386.159 267 64(18) × 10−15 | 4.7 × 10−10 | −1.4 σ of 2010 |
| 2010 | 386.159 268 00(25) × 10−15 | 6.5 × 10−10 | +6.4 σ of 2006 |
| 2006 | 386.159 264 59(53) × 10−15 | 1.4 × 10−9 | −1.2 σ of 2002 |
| 2002 | 386.159 2678(26) × 10−15 | 6.7 × 10−9 | +1.3 σ of 1998 |
| 1998 | 386.159 2642(28) × 10−15 | 7.3 × 10−9 |
“Change from previous” is the shift in the value divided by the standard uncertainty of the previous adjustment. Earlier values are converted into the current unit where NIST changed it (for example J s to J Hz⁻¹).