# -*- coding: utf-8 -*-
from __future__ import (absolute_import, division, print_function)
# From Kielland, Individual Activity Coefficients of Ions in Aqueous Solutions, Vol. 59, 1937, 1675-1678
_radii_nm = { # in nanometer, from Table I, Page 1676
'H+': .9,
'Li+': .6,
'Na+': .425,
'K+': .3,
'Rb+': .25,
'Cs+': .25,
'NH4+': .25,
'Tl+': .25,
'Ag+': .25,
'Be+2': .8,
'Mg+2': .8,
'Ca+2': .6,
'Sr+2': .5,
'Ba+2': .5,
'Ra+2': .5,
'Cu+2': .6,
'Zn+2': .6,
'Cd+2': .5,
'Hg+2': .5,
'Pb+2': .45,
'Mn+2': .6,
'Fe+2': .6,
'Ni+2': .6,
'Co+2': .6,
'Sn+2': .6,
'Al+3': .9,
'Fe+3': .9,
'Cr+3': .9,
'La+3': .9,
'Ce+3': .9,
'Pr+3': .9,
'Nd+3': .9,
'Sc+3': .9,
'Sm+3': .9,
'Y+3': .9,
'In+3': .9,
'Sn+4': 1.1,
'Th+4': 1.1,
'Zr+4': 1.1,
'Ce+4': 1.1,
'F-': .35,
'Cl-': .3,
'Br-': .3,
'I-': .3,
'ClO3-': .35,
'ClO4-': .35,
'NO3-': .3,
'BrO3-': .35,
'IO3-': .425,
'HCO3-': .425,
'S-2': .5,
'CO3-2': .45,
'SO4-2': .4,
'C2O4-2': .45,
'SCN-': 0.35,
'OH-': .35,
}
[docs]def get_radii(key, units=None):
""" Get Debye-Hückel radii for various ions
For aqueous systems
Parameters
----------
key: str
e.g. 'Fe+3', 'SCN-'
units: object (optional)
:attr:`nm` is accessed.
Returns
-------
radius in nanometers
"""
if units is None:
return _radii_nm[key]
else:
return _radii_nm[key]*units.nm