refractivity¶
All data and methods for estimating a chemical’s refractivity.
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thermosteam.properties.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
CASRN (string) – CASRN [-]
- Returns
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
- Other Parameters
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 [1]_.
Examples
>>> refractive_index(CASRN='64-17-5') (1.3611, 293.15)
References
- 1
Haynes, W.M., Thomas J. Bruno, and David R. Lide. CRC Handbook of Chemistry and Physics, 95E. Boca Raton, FL: CRC press, 2014.
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thermosteam.properties.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]
- Returns
alpha – Polarizability [m^3]
- Return type
float
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.
Examples
>>> polarizability_from_RI(1.3611, 5.8676E-5) 5.147658123614415e-30
References
- 1
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.
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thermosteam.properties.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]
- Returns
Rm – Molar refractivity [m^3/mol]
- Return type
float
Notes
Examples
>>> molar_refractivity_from_RI(1.3611, 5.8676E-5) 1.2985217089649597e-05
References
- 1
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.
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thermosteam.properties.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]
- Returns
RI – Refractive Index on Na D line, [-]
- Return type
float
Notes
Examples
>>> RI_from_molar_refractivity(1.2985e-5, 5.8676E-5) 1.3610932757685672
References
- 1
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.