In situ Detection of Adsorbates at Silica/Solution Interfaces by Fourier Transform Infrared Attenuated Total Reflection Spectroscopy Using a Silica-Coated Internal Reflection Element

Abstract

A silica-coated ZnSe internal reflection element (IRE) was used to acquire attenuated total reflection (ATR) Fourier transform infrared (FT-IR) spectra of ethyl acetate at an n-heptane/silica surface. A thin silica film was deposited onto the IRE by withdrawing the substrate from a suspension of fumed silica; upon drying, a durable, porous SiO₂ layer is formed on the IRE that is stable in contact with aprotic solvents. The layer thickness is targeted to be comparable to the depth of penetration of infrared radiation beyond the IRE/film interface. These films were used to investigate the adsorption of ethyl acetate onto silica from n-heptane. A multidimensional least-squares fit of the spectroscopic data reveals multiple surface-site energies on the silica surface, as reflected in both the solution concentration dependence of ethyl acetate accumulation on the surface and the frequencies of vibrational modes that shift upon adsorption.

Keywords

ATR FT-IR Adsorption Liquid/solid interfaces

Get full access to this article

View all access options for this article.

References

Iler

R. K.

, The Chemistry of Silica (John Wiley and Sons, New York, 1979).

Ungar

, Porous Silica (Elsevier Scientific, Amsterdam, 1979).

Brinker

C. J.

and Scherer

G. W

, Sol-Gel Science (Academic Press, San Diego, California, 1989).

Stahlberg

and Almgren

, Anal. Chem. 57, 817 (1985).

Carr

J. W.

and Harris

J. M

, Anal. Chem. 58, 626 (1986).

Carr

J. W.

and Harris

J. M

, Anal. Chem. 59, 2546 (1987).

Lochmüller

C. H.

Marshall

D. B.

and Wilder

D. R

, Anal. Chim. Acta 130, 31 (1981).

Lochmüller

C. H.

Marshall

D. B.

and Harris

J. M

, Anal. Chim. Acta 131, 263 (1981).

Lochmüller

C. H.

Colborn

A. S.

Hunnicutt

M. L.

and Harris

J. M

, J. Am. Chem. Soc. 106, 4077 (1984).

10.

Jones

J. L.

and Rutan

S. C

, Anal. Chem. 63, 1318 (1991).

11.

Simpson

S. F.

and Harris

J. M

, J. Phys. Chem. 94, 4649 (1990).

12.

Matzner

R. A.

Bales

R. C.

and Pemberton

J. E

, Appl. Spectrosc. 48, 1043 (1994).

13.

Doyle

C. A.

Vickers

T. J.

Mann

C. K.

and Dorsey

J. G

, J. Chromatogr. A 779, 91 (1997).

14.

Cai

and Pemberton

J. E

, Anal. Chem. 69, 2613 (1997).

15.

Thompson

W. R.

and Pemberton

J. E

, Chem. Mater. 5, 241 (1993).

16.

Thompson

W. R.

and Pemberton

J. E

, Chem. Mater. 7, 130 (1995).

17.

Harrick

N. J.

, Internal Reflection Spectroscopy (Harrick Scientific Corporation, Ossining, New York, 1979).

18.

Sperline

R. P.

Muralidharan

and Freiser

, Langmuir 3, 198 (1987).

19.

Kellar

J. J.

Cross

W. M.

and Miller

J. D

, Appl. Spectrosc. 43, 1456 (1989).

20.

Parry

D. B.

and Harris

J. M

, Appl. Spectrosc. 42, 997 (1988).

21.

Parry

D. B.

and Harris

J. M

, “Attenuated Total Relectance FTIR for Measuring Interfacial Reaction Kinetics at Silica Surfaces”, in Chemically Modified Oxide Surfaces, Leyden

D. E.

Collins

W. T.

and Lochmüller

C. H

, Eds. (Gordon and Breach, New York, 1990), pp. 127–136.

22.

Hug

S. J.

and Sulzberger

, Langmuir 10, 3587 (1994).

23.

Connor

P. A.

Dobson

K. D.

and McQuillan

A. J

, Langmuir 11, 4193 (1995).

24.

Han

Niemczyk

T. M.

and Lopez

G. P

, Appl. Spectrosc. 52, 119 (1998).

25.

Sperline

R. P.

Song

and Freiser

, Langmuir 8, 2183 (1992).

26.

Sperline

R. P.

Song

and Freiser

, Langmuir 10, 37 (1994).

27.

Scott

R. P. W.

and Kucera

, J. Chromatogr. 149, 93 (1978).

28.

Lacy

W. B.

Olson

and Harris

J. M

, Anal. Chem., paper in revision.

29.

Snyder

R. L.

and Poppe

, J. Chromatogr. 184, 363 (1980).

30.

Scott

R. P. W.

, J. Chromatogr. Sci. 18, 297 (1980).

31.

Scott

R. P. W.

and Kucera

, J. Chromatogr. 171, 37 (1979).

32.

Draper

N. R.

and Smith

, Applied Regression Analysis (John Wiley and Sons, New York, 1981), 2nd ed., Chap. 2.

33.

Wong

A. L.

and Harris

J. M

, Anal. Chem. 61, 2315 (1989).

34.

Nelder

J. A.

and Mead

, Comput. J. 7, 308 (1965).

35.

Goplen

T. G.

Cameron

D. G.

and Jones

R. N

, Appl. Spectrosc. 34, 657 (1980).

36.

Philipp

H. R.

, J. Appl. Phys. 50, 1053 (1979).

37.

Sperline

R. P.

Muralidharan

and Freiser

, Appl. Spectrosc. 40, 1019 (1986).

38.

Palik

E. D.

, Handbook of Optical Constants of Solids (Academic Press, Orlando, Florida, 1985).

39.

Colthup

N. B.

Daly

L. H.

and Wiberley

S. E

, in Introduction to Infrared and Raman Spectroscopy (Academic Press, New York, 1990), 3rd ed.

40.

Lin-Vien

Colthup

N. B.

Fateley

W. G.

and Grasselli

J. G

, The Handbook of Infrared and Raman Characteristic Frequencies of Organic Molecules (Academic Press, San Diego, California, 1991).

41.

Snyder

L. R.

, Principles of Adsorption Chromatography (Marcel Decker, New York, 1968).

42.

Doyle

W. M.

, Appl. Spectrosc. 44, 50 (1990).

43.

Langmuir

, J. Am. Chem. Soc. 40, 1361 (1918).

44.

Eaton

D. F.

, Pure Appl. Chem. 62, 1631 (1990).

45.

Frumkin

A. N.

, Z. Phys. Chem. 116, 466 (1925).

46.

Snyder

L. R.

and Poppe

, J. Chromatogr. 184, 363 (1980).