# einstein_coeff¶

sbpy.activity.einstein_coeff(mol_data)[source]

Einstein coefficient from molecular data

Parameters
mol_dataphys

phys object that contains the following data, using astropy.units for the required units:

• Transition frequency in MHz

• Temperature in Kelvins

• Integrated line intensity at 300 K in MHz * nm**2

• Integrated line intensity at desired temperature

• Partition function at 300 K (Dimensionless)

• Partition function at designated temperature (Dimensionless)

• Upper state degeneracy (Dimensionless)

• Upper level energy in Joules

• Lower level energy in Joules

• Degrees of freedom (Dimensionless)

Keywords that can be used for these values are found under fieldnames documentation. We recommend the use of the JPL Molecular Spectral Catalog and the use of from_jplspec to obtain these values in order to maintain consistency. Yet, if you wish to use your own molecular data, it is possible. Make sure to inform yourself on the values needed for each function, their units, and their interchangeable keywords as part of the data class.

Returns
einstein_coeffQuantity

Spontaneous emission coefficient (1/s), which can be appended to the original sbpy.phys object for future calculations