Constants (erlab.constants)

Physical constants and unit conversion.

Module Attributes

e	Elementary charge \(e\) (C)
c	Speed of light \(c\) (m/s)
m_e	Electron mass \(m_e\) (kg) (±0.000 000 0028e-31)
mcsq	Electron rest energy \(m_e c^2\) (J) (±0.000 000 0025e-14)
mcsq_eV	Electron rest energy \(m_e c^2\) (eV) (±0.000 15)
h	Planck constant \(h\) (J·s)
hc	\(hc\) (J·m)
hbar	Dirac constant \(\hbar\) (J·s)
hbarc	\(\hbar c\) (J·m)
hbarsq	\(\hbar^2\) (J²·s²)
h_eV	Planck constant \(h\) (eV·s)
hc_eV	\(hc\) (eV·m)
hbar_eV	Dirac constant \(\hbar\) (eV·s)
hbarsq_eV	\(\hbar^2\) (eV²·s²)
rel_eV_nm	\(hc\) (eV·nm), Used in energy-wavelength conversion
rel_kconv	\(\frac{\sqrt{2 m_e}}{\hbar}\), Used in momentum conversion
rel_kzconv	\(\frac{\hbar^2}{2 m_e}\), Used in momentum conversion
kb	Boltzmann constant \(k_B\) (J/K)
kb_eV	Boltzmann constant \(k_B\) (eV/K)

Functions

conv_eV_nm(value)	Convert between energy and wavelength.
conv_watt_photons(value, wavelength)	Convert Watts to photons per second.

erlab.constants.conv_eV_nm(value)

Convert between energy and wavelength.

erlab.constants.conv_watt_photons(value, wavelength)

Convert Watts to photons per second.

Parameters:

• value (float) – Power in Watts.

• wavelength (float) – Wavelength in nanometers.

Returns:

power – Power in photons per second.

Return type:

float

erlab.constants.c: float = 299792458.0

Speed of light \(c\) (m/s)

erlab.constants.e: float = 1.602176634e-19

Elementary charge \(e\) (C)

erlab.constants.h: float = 6.62607015e-34

Planck constant \(h\) (J·s)

erlab.constants.h_eV: float = 4.135667696923859e-15

Planck constant \(h\) (eV·s)

erlab.constants.hbar: float = 1.0545718176461565e-34

Dirac constant \(\hbar\) (J·s)

erlab.constants.hbar_eV: float = 6.582119569509067e-16

Dirac constant \(\hbar\) (eV·s)

erlab.constants.hbarc: float = 3.1615267734966903e-26

\(\hbar c\) (J·m)

erlab.constants.hbarsq: float = 1.1121217185735183e-68

\(\hbar^2\) (J²·s²)

erlab.constants.hbarsq_eV: float = 4.332429802731423e-31

\(\hbar^2\) (eV²·s²)

erlab.constants.hc: float = 1.9864458571489286e-25

\(hc\) (J·m)

erlab.constants.hc_eV: float = 1.2398419843320028e-06

\(hc\) (eV·m)

erlab.constants.kb: float = 1.380649e-23

Boltzmann constant \(k_B\) (J/K)

erlab.constants.kb_eV: float = 8.617333262145179e-05

Boltzmann constant \(k_B\) (eV/K)

erlab.constants.m_e: float = 9.1093837015e-31

Electron mass \(m_e\) (kg) (±0.000 000 0028e-31)

erlab.constants.m_n: float = 1.67492749804e-27

Neutron mass \(m_n\) (kg) (±0.000 000 000 95e-27)

erlab.constants.mcsq: float = 8.1871057769e-14

Electron rest energy \(m_e c^2\) (J) (±0.000 000 0025e-14)

erlab.constants.mcsq_eV: float = 510998.95

Electron rest energy \(m_e c^2\) (eV) (±0.000 15)

erlab.constants.rel_eV_nm: float = 1239.8419843320028

\(hc\) (eV·nm), Used in energy-wavelength conversion

erlab.constants.rel_kconv: float = 0.512316721967493

\(\frac{\sqrt{2 m_e}}{\hbar}\), Used in momentum conversion

erlab.constants.rel_kzconv: float = 3.8099821161548606

\(\frac{\hbar^2}{2 m_e}\), Used in momentum conversion