# thermo.refractivity module¶

thermo.refractivity.refractive_index(CASRN, T=None, AvailableMethods=False, Method=None, full_info=True)[source]

This function handles the retrieval of a chemical’s refractive index. Lookup is based on CASRNs. Will automatically select a data source to use if no Method is provided; returns None if the data is not available.

Function has data for approximately 4500 chemicals.

Parameters: Returns: CASRN : string CASRN [-] RI : float Refractive Index on the Na D line, [-] T : float, only returned if full_info == True Temperature at which refractive index reading was made methods : list, only returned if AvailableMethods == True List of methods which can be used to obtain RI with the given inputs Method : string, optional A string for the method name to use, as defined by constants in RI_methods AvailableMethods : bool, optional If True, function will determine which methods can be used to obtain RI for the desired chemical, and will return methods instead of RI full_info : bool, optional If True, function will return the temperature at which the refractive index reading was made

Notes

Only one source is available in this function. It is:

• ‘CRC’, a compillation of Organic RI data in [R10561059].

References

 [R10561059] (1, 2) Haynes, W.M., Thomas J. Bruno, and David R. Lide. CRC Handbook of Chemistry and Physics, 95E. Boca Raton, FL: CRC press, 2014.

Examples

>>> refractive_index(CASRN='64-17-5')
(1.3611, 293.15)

thermo.refractivity.polarizability_from_RI(RI, Vm)[source]

Returns the polarizability of a fluid given its molar volume and refractive index.

$\alpha = \left(\frac{3}{4\pi N_A}\right) \left(\frac{n^2-1}{n^2+2}\right)V_m$
Parameters: RI : float Refractive Index on Na D line, [-] Vm : float Molar volume of fluid, [m^3/mol] alpha : float Polarizability [m^3]

Notes

This Lorentz-Lorentz-expression is most correct when van der Waals interactions dominate. Alternate conversions have been suggested. This is often expressed in units of cm^3 or Angstrom^3. To convert to these units, multiply by 1E9 or 1E30 respectively.

References

 [R10571060] Panuganti, Sai R., Fei Wang, Walter G. Chapman, and Francisco M. Vargas. “A Simple Method for Estimation of Dielectric Constants and Polarizabilities of Nonpolar and Slightly Polar Hydrocarbons.” International Journal of Thermophysics 37, no. 7 (June 6, 2016): 1-24. doi:10.1007/s10765-016-2075-8.

Examples

>>> polarizability_from_RI(1.3611, 5.8676E-5)
5.147658123614415e-30

thermo.refractivity.molar_refractivity_from_RI(RI, Vm)[source]

Returns the molar refractivity of a fluid given its molar volume and refractive index.

$R_m = \left(\frac{n^2-1}{n^2+2}\right)V_m$
Parameters: RI : float Refractive Index on Na D line, [-] Vm : float Molar volume of fluid, [m^3/mol] Rm : float Molar refractivity [m^3/mol]

References

 [R10581061] Panuganti, Sai R., Fei Wang, Walter G. Chapman, and Francisco M. Vargas. “A Simple Method for Estimation of Dielectric Constants and Polarizabilities of Nonpolar and Slightly Polar Hydrocarbons.” International Journal of Thermophysics 37, no. 7 (June 6, 2016): 1-24. doi:10.1007/s10765-016-2075-8.

Examples

>>> molar_refractivity_from_RI(1.3611, 5.8676E-5)
1.2985217089649597e-05

thermo.refractivity.RI_from_molar_refractivity(Rm, Vm)[source]

Returns the refractive index of a fluid given its molar volume and molar refractivity.

$RI = \sqrt{\frac{-2R_m - V_m}{R_m-V_m}}$
Parameters: Rm : float Molar refractivity [m^3/mol] Vm : float Molar volume of fluid, [m^3/mol] RI : float Refractive Index on Na D line, [-]

References

 [R10591062] Panuganti, Sai R., Fei Wang, Walter G. Chapman, and Francisco M. Vargas. “A Simple Method for Estimation of Dielectric Constants and Polarizabilities of Nonpolar and Slightly Polar Hydrocarbons.” International Journal of Thermophysics 37, no. 7 (June 6, 2016): 1-24. doi:10.1007/s10765-016-2075-8.

Examples

>>> RI_from_molar_refractivity(1.2985e-5, 5.8676E-5)
1.3610932757685672