Abstract

The construction, physical function, and use of a wedge-shaped cell for measuring the Lambert adsorption coefficient of highly absorbent liquids is described. Liquids are held in the cell by surface tension, thus avoiding the use of seals. The cell is simple in its design and is about as convenient to use as an ordinary cuvette.

© 1978 Optical Society of America

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References

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  1. C. W. Robertson, D. Williams, J. Opt. Soc. Am. 61, 1316 (1971).
    [CrossRef]
  2. K. F. Palmer, D. Williams, J. Opt. Soc. Am. 64, 1107 (1974).
    [CrossRef]
  3. Manufactured by De-Sta-Co., Division, Dover Corp., Detroit, Mich. 48203.
  4. Manufactured by Vlier Engineering Corp., Burbank, Calif. 91505.
  5. No. A-45-302-0, Oriel Corp., Stanford, Conn. 06902.
  6. No. 667, L. S. Starrett Co., Athol, Mass. 01331.
  7. Use of the relation (z2 − z1) = Δx tanθ, where θ is the wedge angle and Δx is the vertical translation distance, is still valid for use in Eq. (2), even though there is now a finite vertical aperture.
  8. This assumption is valid provided that the wedge angle is large enough and the measurement wavelength is short enough so at least a couple of interference fringes are in view through the verticle aperture. The maximum error in T(ν,z) caused by interference effects can be shown to be σ I = 2(nl − nw)2[(2n + 1)-π(nl + nw)2]−1, where n is the number of complete fringes in view and nl and nw are the sample and window indices of refraction. For example, with a 25-μm spacer the error in T(ν,z) would be less than 0.2% at a wavelength of 3 μm for most samples and window materials.
  9. These same effects cause an increase of the sample surface area at the exposed edges of the cell. With spacers of 25 μm or less, this results in a significant surface-to-volume ratio. If measurements with narrow spacers require more than an hour or so, it, therefore, is advisable to place pieces of Teflon pipe dope along the two exposed edges after the cell is closed.
  10. I. L. Tyler, M. R. Querry, Bull. Am. Phys. Soc. 22, 641 (1977).
  11. M. R. Querry, I. L. Tyler, W. E. Holland, Bull. Am. Phys. Soc. 22, 641 (1977).

1977 (2)

I. L. Tyler, M. R. Querry, Bull. Am. Phys. Soc. 22, 641 (1977).

M. R. Querry, I. L. Tyler, W. E. Holland, Bull. Am. Phys. Soc. 22, 641 (1977).

1974 (1)

1971 (1)

Holland, W. E.

M. R. Querry, I. L. Tyler, W. E. Holland, Bull. Am. Phys. Soc. 22, 641 (1977).

Palmer, K. F.

Querry, M. R.

I. L. Tyler, M. R. Querry, Bull. Am. Phys. Soc. 22, 641 (1977).

M. R. Querry, I. L. Tyler, W. E. Holland, Bull. Am. Phys. Soc. 22, 641 (1977).

Robertson, C. W.

Tyler, I. L.

M. R. Querry, I. L. Tyler, W. E. Holland, Bull. Am. Phys. Soc. 22, 641 (1977).

I. L. Tyler, M. R. Querry, Bull. Am. Phys. Soc. 22, 641 (1977).

Williams, D.

Bull. Am. Phys. Soc. (2)

I. L. Tyler, M. R. Querry, Bull. Am. Phys. Soc. 22, 641 (1977).

M. R. Querry, I. L. Tyler, W. E. Holland, Bull. Am. Phys. Soc. 22, 641 (1977).

J. Opt. Soc. Am. (2)

Other (7)

Manufactured by De-Sta-Co., Division, Dover Corp., Detroit, Mich. 48203.

Manufactured by Vlier Engineering Corp., Burbank, Calif. 91505.

No. A-45-302-0, Oriel Corp., Stanford, Conn. 06902.

No. 667, L. S. Starrett Co., Athol, Mass. 01331.

Use of the relation (z2 − z1) = Δx tanθ, where θ is the wedge angle and Δx is the vertical translation distance, is still valid for use in Eq. (2), even though there is now a finite vertical aperture.

This assumption is valid provided that the wedge angle is large enough and the measurement wavelength is short enough so at least a couple of interference fringes are in view through the verticle aperture. The maximum error in T(ν,z) caused by interference effects can be shown to be σ I = 2(nl − nw)2[(2n + 1)-π(nl + nw)2]−1, where n is the number of complete fringes in view and nl and nw are the sample and window indices of refraction. For example, with a 25-μm spacer the error in T(ν,z) would be less than 0.2% at a wavelength of 3 μm for most samples and window materials.

These same effects cause an increase of the sample surface area at the exposed edges of the cell. With spacers of 25 μm or less, this results in a significant surface-to-volume ratio. If measurements with narrow spacers require more than an hour or so, it, therefore, is advisable to place pieces of Teflon pipe dope along the two exposed edges after the cell is closed.

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Figures (2)

Fig. 1
Fig. 1

An exploded drawing of components comprising a thin-wedge-shaped cell for measuring the Lambert absorption coefficient of highly absorbent liquids. The windows determine the cell dimensions.

Fig. 2
Fig. 2

Cross-sectional view of the cell windows, liquid sample, and feeler-stock spacer shown in the vertical orientation in which the cell is used. In (a) the sample fills the vertex region between the windows. In (b) the sample is virtually displaced a distance x from the vertex.

Tables (2)

Tables Icon

Table I Calculated Upper Bounds for the Cell Thickness D for Some Common Solvents [Values Obtained Using Eq. (5) with L = 5 cm]

Tables Icon

Table II Lambert Absorption Coefficients α(ν)l and Values for k(ν), = α(ν),/4πν at ν = 4444.4 cm−1 for Aqueous Solutions of ZnCl2 and for Phosphoric Acid

Equations (5)

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T ( ν , z ) = t ( ν ) α 2 t ( ν ) l 2 exp [ 2 d α ( ν ) w z α ( ν ) l ] ,
α ( ν ) l = ln [ T ( ν , z 1 ) / T ( ν , z 2 ) ] / ( z 2 z 1 ) .
Δ = [ D γ l υ / + 2 ( γ w υ γ w l ) ] x ,
W = D S 2 ρ g / 2 L ,
D MAX 4 γ l υ / L ρ g .

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