# 6.2. Spectroscopic Emission Lines¶

class cherab.core.atomic.line.Line

A class fully specifies an observed spectroscopic emission line.

Note that wavelengths are not arguments to this class. This is because in principle the transition has already been fully specified with the other three arguments. The wavelength is looked up in the wavelength database of the atomic data provider.

Parameters
• element (Element) – The atomic element/isotope to which this emission line belongs.

• charge (int) – The charge state of the element/isotope that emits this line.

• transition (tuple) – A two element tuple that defines the upper and lower electron configuration states of the transition. For hydrogen-like ions it may be enough to specify the n-levels with integers (e.g. (3,2)). For all other ions the full spectroscopic configuration string should be specified for both states. It is up to the atomic data provider package to define the exact notation.

>>> from cherab.core.atomic import Line, deuterium, carbon
>>>
>>> # Specifying the d-alpha and d-gamma balmer lines
>>> d_alpha = Line(deuterium, 0, (3, 2))
>>> d_beta = Line(deuterium, 0, (4, 2))
>>>
>>> # Specifying a CIII line at 465nm
>>> ciii_465 = Line(carbon, 2, ('2s1 3p1 3P4.0', '2s1 3s1 3S1.0'))

class cherab.core.atomic.zeeman.ZeemanStructure

Provides wavelengths and ratios of $$\pi$$-/$$\sigma$$-polarised Zeeman components for any given value of magnetic field strength.

Parameters
• pi_components (list) – A list of 2-tuples of Function1D objects that provide the wavelengths and ratios of individual $$\pi$$-polarised Zeeman components for a given magnetic field strength: [(wvl_func1, ratio_func1), (wvl_func2, ratio_func2), …]

• sigma_plus_components (list) – A list of 2-tuples of Function1D objects that provide the wavelengths and ratios of individual $$\sigma^{+}$$-polarised Zeeman components for a given magnetic field strength: [(wvl_func1, ratio_func1), (wvl_func2, ratio_func2), …]

• sigma_minus_components (list) – A list of 2-tuples of Function1D objects that provide the wavelengths and ratios of individual $$\sigma^{-}$$-polarised Zeeman components for a given magnetic field strength: [(wvl_func1, ratio_func1), (wvl_func2, ratio_func2), …]