Appendix A: Fundamental Constants and Useful
Conversion Factors
Table A.1 Fundamental constants
Symbol
Quantity
Magnitude
Units
e
Electron charge
1.6022 Â 10
À19
C
h
Planck’s constant
6.6260 Â 10
À34
J s
ħ
Reduced Planck’s constant
1.0546 Â 10
À34
J s
c
Speed of light
2.9979 Â 10
8
m s
À1
m e
Electron rest mass
9.1094 Â 10
À31
kg
ε 0
Permittivity of vacuum
8.8542 Â 10
À12
F m
À1
μ 0
Permeability of vacuum
4π Â 10
À7
H m
À1
m e c
2
Electron rest mass energy
0.5110
MeV
N A
Avogadro’s number
6.0221 Â 10
23
mol
À1
k B
Boltzmann’s constant
1.3806 Â 10
À23
J K
À1
μ
Atomic mass unit
1.6605 Â 10
À27
kg
R H
Rydberg constant
13.606
eV
a 0
Bohr radius
0.5292
Å
μ B
Bohr magneton
9.2740 Â 10
À24
J T
À1
r 0
Classical electron radius
2.818 Â 10
À15
m
λ C
Compton scattering length
3.860 Â 10
À13
m
© Springer Nature Switzerland AG 2020
S. P. Cramer, X-Ray Spectroscopy with Synchrotron Radiation, Biological and Medical
Physics, Biomedical Engineering, https://doi.org/10.1007/978-3-030-28551-7
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