utils¶

starkzee.utils.species_to_ZA(species)[source]¶

Return (Z, A) for a species name string.

Parameters:

species (str) – Species identifier, case-insensitive. Accepted values: 'H' / 'hydrogen', 'D' / 'deuterium', 'T' / 'tritium'.

Returns:

Z (int) – Nuclear charge number.
A (int) – Atomic mass number (most abundant isotope).

Raises:

ValueError – If species is not in the lookup table.

starkzee.utils.nuclear_mass_kg(Z, A=None)[source]¶

Return the nuclear mass [kg] for nuclear charge Z and mass number A.

Parameters:

Z (int) – Nuclear charge number.
A (int, optional) – Atomic mass number. When supplied the isotope-specific CODATA value is used (H, D, T, ⁴He); otherwise falls back to the most-abundant isotope for that Z.

Returns:

Nuclear mass in kg.

Return type:

float

starkzee.utils.reduced_mass_rydberg_ev(Z, A=None)[source]¶

Return the reduced-mass-corrected Rydberg energy for nuclear charge Z [eV].

Replaces the infinite-nuclear-mass value RYDBERG_EV with the atom-specific value:

R_atom = R_∞ × μ / m_e = R_∞ / (1 + m_e / M_nucleus)

where M_nucleus is the nuclear mass from nuclear_mass_kg().

Parameters:: Z (int) – Nuclear charge number (1 = hydrogen, 2 = helium, etc.).
Returns:: Reduced-mass-corrected Rydberg energy [eV].
Return type:: float

starkzee.utils.temp_ev_to_joules(t_ev)[source]¶

Convert a thermal energy from eV to Joules.

Uses the exact SI definition e = 1.602176634e-19 C so that 1 eV = e × 1 J exactly.

Parameters:: t_ev (float or array-like) – Energy in electronvolts [eV].
Returns:: Energy in Joules [J].
Return type:: float or ndarray

starkzee.utils.temp_ev_to_kelvin(t_ev)[source]¶

Convert a thermal energy from eV to the equivalent temperature in Kelvin.

Uses k_B T = e × T_eV, so T [K] = e / k_B × T_eV.

Parameters:: t_ev (float or array-like) – Thermal energy in electronvolts [eV].
Returns:: Equivalent temperature in Kelvin [K].
Return type:: float or ndarray

starkzee.utils.energy_ev_to_wavelength_nm(energy_ev)[source]¶

Convert photon energy in eV to vacuum wavelength in nm.

Uses the relation E = hc / λ, giving λ [nm] = hc [eV·nm] / E [eV].

Parameters:: energy_ev (float or array-like) – Photon energy [eV]. Zero-valued elements are mapped to zero wavelength rather than triggering a division-by-zero error.
Returns:: Vacuum wavelength [nm]. For an increasing energy array the returned wavelengths are in decreasing order.
Return type:: float or ndarray

Notes

hc = 2π ħ c ≈ 1239.842 eV·nm. The code derives this from CODATA values of ħ and c so there is no hardcoded conversion constant.

starkzee.utils.vacuum_to_air_wavelength_nm(wavelength_vac_nm)[source]¶

Convert vacuum wavelength(s) to air wavelength(s) using the Edlén (1966) formula.

Valid for standard dry air (15 °C, 101 325 Pa) over approximately 200–2000 nm. The formula is the one used by NIST ASD for all tabulated air wavelengths.

Parameters:: wavelength_vac_nm (float or array-like) – Vacuum wavelength [nm].
Returns:: Air wavelength [nm].
Return type:: float or ndarray

Notes

Edlén (1966) dispersion formula:

(n − 1) × 10⁸ = 8342.13 + 2406030 / (130 − σ²) + 15997 / (38.9 − σ²)

where σ = 1/λ_vac [µm⁻¹] = 1000 / λ_vac [nm].

References

Edlén, B., Metrologia 2, 71 (1966).

starkzee.utils.wavelength_nm_to_energy_ev(wavelength_nm)[source]¶

Convert vacuum wavelength in nm to photon energy in eV.

Uses E = hc / λ.

Parameters:: wavelength_nm (float or array-like) – Vacuum wavelength [nm]. Must be non-zero.
Returns:: Photon energy [eV]. For an increasing wavelength array the returned energies are in decreasing order.
Return type:: float or ndarray

starkzee.utils.frequency_thz_to_energy_ev(frequency_thz)[source]¶

Convert photon frequency in THz to energy in eV.

Uses E = h·f.

Parameters:: frequency_thz (float or array-like) – Photon frequency [THz].
Returns:: Photon energy [eV].
Return type:: float or ndarray

starkzee.utils.energy_ev_to_frequency_thz(energy_ev)[source]¶

Convert photon energy in eV to frequency in THz.

Uses f = E / h.

Parameters:: energy_ev (float or array-like) – Photon energy [eV].
Returns:: Photon frequency [THz].
Return type:: float or ndarray

starkzee.utils.wavenumber_cm_to_energy_ev(wavenumber_cm)[source]¶

Convert photon wavenumber in cm⁻¹ to energy in eV.

Uses E = hc·ν̃.

Parameters:: wavenumber_cm (float or array-like) – Photon wavenumber [cm⁻¹].
Returns:: Photon energy [eV].
Return type:: float or ndarray

starkzee.utils.energy_ev_to_wavenumber_cm(energy_ev)[source]¶

Convert photon energy in eV to wavenumber in cm⁻¹.

Uses ν̃ = E / (hc).

Parameters:: energy_ev (float or array-like) – Photon energy [eV].
Returns:: Photon wavenumber [cm⁻¹].
Return type:: float or ndarray