This paper describes how a conventional Pulfrich refractometer can be modified for use with laser light sources for the precise determination of the refractive index of liquids. Measurements carried out on water, several organic liquids, and KCI solutions are reported. The performance as a differential refractometer in view of determinations of specific refractive-index increments (∂n/∂c) at laser wavelengths is also presented.
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Dispersion Coefficients for the Measuring Prisms at 20°Ca
Prism
Au
Zu
Vo
n0
1.593079
1.591020
1.703773
n2 × 10−4 (nm−2)
0.86570
0.86025
1.30595
n4 × 10−8 (nm−4)
−1.153
−1.186
−1.774
n6 × 10−13 (nm−6)
2.948
2.939
6.470
The refractive index of each prism is given as a function of wavelength in nanometers by n(λ) = n0 + n2/λ2 + n4/λ4 + n6/λ6.
Table II
Refractive Index at Ar-Ion and He–Ne Laser Light Wavelengths of Bidistilled Water at 25°Ca
Wavelength (nm)
Refractive index
This work
Tilton and Taylor
476.5
1.33711
1.33714
488.0
1.33652
1.33653
496.5
1.33609
1.33610
514.5
1.33526
1.33526
632.8
1.33128
1.33126
The values from the general interpolation table of Tilton and Taylor,13 given up to seven digits after the decimal point, are given here only up to the fifth digit for comparison.
Table III
Refractive Index at 20°C of Some Organic Liquids
Wavelength (nm)
Liquid
476.5
488.0
496.5
514.5
632.8
Toluene
1.51008
1.50826
1.50701
1.50456
1.49390
Benzene
1.51473
1.51284
1.51152
1.50898
1.49792
Carbon tetrachloride
1.46824
1.46721
1.46646
1.46509
1.45876
Cyclohexane
1.43243
1.43158
1.43105
1.42989
1.42490
Ethanol
1.36644
1.36580
1.36531
1.36445
1.36039
Acetone
1.36449
1.36377
1.36322
1.36226
1.35782
Table IV
Refractive Index at 25°C of Some Organic Liquids
Wavelength (nm)
Liquid
476.5
488.0
496.5
514.5
632.8
Toluene
1.50738
1.50553
1.50430
1.50190
1.49130
Benzene
1.51088
1.50909
1.50787
1.50539
1.49529
Carbon tetrachloride
1.46535
1.46432
1.46363
1.46223
1.45599
Cyclohexane
1.43016
1.42935
1.42877
1.42772
1.42274
Ethanol
1.36469
1.36399
1.36356
1.36270
1.35867
Acetone
1.36225
1.36150
1.36097
1.36000
1.35563
Table V
Difference In Refractive Index Δn Between Several KCI Solutions and Bidistilled Water at 25°C; Δn × 106 is Tabulated
Concentration (kg/m3)
Wavelength (nm)
476.5
488.0
496.5
514.5
632.8
0.7623
124
81
97
104
93
3.734
491
454
461
474
433
7.462
1009
964
978
998
927
11.52
1566
1533
1517
1538
1486
15.35
2086
2055
2032
2049
1978
19.27
2603
2574
2560
2587
2476
22.86
3189
3127
3145
3130
3037
45.72
6148
6150
6143
6119
5966
69.47
9290
9262
9227
9214
9002
93.68
12421
12366
12374
12310
12009
117.9
15523
15432
15418
15402
15036
142.9
18665
18587
18527
18437
18027
168.5
21816
21709
21653
21577
21090
Table VI
Specific Refractive-index Increment (∂n/∂c) of KCI Solutions in Water at 25°C
Dispersion Coefficients for the Measuring Prisms at 20°Ca
Prism
Au
Zu
Vo
n0
1.593079
1.591020
1.703773
n2 × 10−4 (nm−2)
0.86570
0.86025
1.30595
n4 × 10−8 (nm−4)
−1.153
−1.186
−1.774
n6 × 10−13 (nm−6)
2.948
2.939
6.470
The refractive index of each prism is given as a function of wavelength in nanometers by n(λ) = n0 + n2/λ2 + n4/λ4 + n6/λ6.
Table II
Refractive Index at Ar-Ion and He–Ne Laser Light Wavelengths of Bidistilled Water at 25°Ca
Wavelength (nm)
Refractive index
This work
Tilton and Taylor
476.5
1.33711
1.33714
488.0
1.33652
1.33653
496.5
1.33609
1.33610
514.5
1.33526
1.33526
632.8
1.33128
1.33126
The values from the general interpolation table of Tilton and Taylor,13 given up to seven digits after the decimal point, are given here only up to the fifth digit for comparison.
Table III
Refractive Index at 20°C of Some Organic Liquids
Wavelength (nm)
Liquid
476.5
488.0
496.5
514.5
632.8
Toluene
1.51008
1.50826
1.50701
1.50456
1.49390
Benzene
1.51473
1.51284
1.51152
1.50898
1.49792
Carbon tetrachloride
1.46824
1.46721
1.46646
1.46509
1.45876
Cyclohexane
1.43243
1.43158
1.43105
1.42989
1.42490
Ethanol
1.36644
1.36580
1.36531
1.36445
1.36039
Acetone
1.36449
1.36377
1.36322
1.36226
1.35782
Table IV
Refractive Index at 25°C of Some Organic Liquids
Wavelength (nm)
Liquid
476.5
488.0
496.5
514.5
632.8
Toluene
1.50738
1.50553
1.50430
1.50190
1.49130
Benzene
1.51088
1.50909
1.50787
1.50539
1.49529
Carbon tetrachloride
1.46535
1.46432
1.46363
1.46223
1.45599
Cyclohexane
1.43016
1.42935
1.42877
1.42772
1.42274
Ethanol
1.36469
1.36399
1.36356
1.36270
1.35867
Acetone
1.36225
1.36150
1.36097
1.36000
1.35563
Table V
Difference In Refractive Index Δn Between Several KCI Solutions and Bidistilled Water at 25°C; Δn × 106 is Tabulated
Concentration (kg/m3)
Wavelength (nm)
476.5
488.0
496.5
514.5
632.8
0.7623
124
81
97
104
93
3.734
491
454
461
474
433
7.462
1009
964
978
998
927
11.52
1566
1533
1517
1538
1486
15.35
2086
2055
2032
2049
1978
19.27
2603
2574
2560
2587
2476
22.86
3189
3127
3145
3130
3037
45.72
6148
6150
6143
6119
5966
69.47
9290
9262
9227
9214
9002
93.68
12421
12366
12374
12310
12009
117.9
15523
15432
15418
15402
15036
142.9
18665
18587
18527
18437
18027
168.5
21816
21709
21653
21577
21090
Table VI
Specific Refractive-index Increment (∂n/∂c) of KCI Solutions in Water at 25°C
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