Abstract

We investigated the performance of fiber-optic resonance Raman probes with a series of experiments to determine the working curves of such probes using model analytes and to investigate the effects of absorbing media. A computer model designed to simulate these experiments is presented, and numerical results are found to be in agreement with the experimental data. Design considerations resulting from these studies are discussed, and novel designs for overcoming problems of coupling efficiency, damage threshold, and sensitivity in absorbing samples are presented. These findings are applied to the design of fiber-optic probes for ultraviolet resonance Raman spectroscopy involving nanosecond pulsed-ultraviolet excitation (225 and 266 nm). These probes have been used to collect what is, to our knowledge, the first reported fiber-optic-linked ultraviolet resonance Raman spectra of tryptophan and DNA.

© 1996 Optical Society of America

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References

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  1. S. D. Schwab, R. L. McCreery, “Versatile, efficient Raman sampling with fiber optics,” Anal. Chem. 56, 2199–2204 (1984).
    [CrossRef]
  2. S. D. Schwab, R. L. McCreery, F. T. Gamble, “Normal and resonance Raman spectroelectrochemistry with fiber optic light collection,” Anal. Chem. 58, 2486–2492 (1986).
    [CrossRef]
  3. P. Plaza, N. Q. Dao, M. Jouan, H. Fevrier, H. Saisse, “Simulation et optimisation des capteurs a` fibres optiques adjacentes,” Appl. Opt. 25, 3448–3454 (1986).
    [CrossRef] [PubMed]
  4. D. Heiman, X. L. Zheng, S. Sprunt, B. B. Goldberg, E. D. Isaacs, “Fiber-optics for spectroscopy,” in Raman Scattering, Luminescence and Spectroscopic Instrumentation in Technology, F. Adar, J. E. Griffiths, J. M. Lerner, eds., Proc. SPIE1055, 96–103 (1989).
  5. M. L. Myrick, S. M. Angel, “Elimination of background in fiber-optic Raman measurements,” Appl. Spectrosc. 44, 565–570 (1990).
    [CrossRef]
  6. J. M. Bello, V. A. Narayanan, D. L. Stokes, T. Vo-Dinh, “Fiber-optic remote sensor for in situ surface-enhanced Raman scattering analysis,” Anal. Chem. 62, 2437–2441 (1990).
    [CrossRef]
  7. M. L. Myrick, S. M. Angel, R. Desiderio, “Comparison of some fiber optic configurations for measurement of luminescence and Raman scattering,” Appl. Opt. 29, 1333–1344 (1990).
    [CrossRef] [PubMed]
  8. S. M. Angel, M. L. Myrick, “Wavelength selection for fiber optic Raman spectroscopy. Part 1,” Appl. Opt. 9, 1350–1352 (1990).
    [CrossRef]
  9. S. W. Kercel, M. J. Roberts, A. A. Garrison, “Recent developments in the development of a fiber-optic based instrument for on-line Raman analysis,” in Raman and Luminescence Spectroscopies in Technology II, F. Adar, J. E. Griffith, eds., Proc. SPIE1336, 144–151 (1990).
  10. M. Jiaying, L. Zhong, “A low stray light Raman microprobe using optical fibers and GRIN lenses,” Appl. Spectrosc. 45, 1302–1304 (1991).
    [CrossRef]
  11. J. Ma, Y. Li, “Optical-fiber Raman probe with low background interference by spatial optimization,” Appl. Spectrosc. 48, 1529–1531 (1994).
    [CrossRef]
  12. D. R. Lombardi, C. K. Mann, T. J. Vickers, “Determination of water in slurries by fiber-optic Raman spectroscopy,” Appl. Spectrosc. 49, 220–223 (1995).
    [CrossRef]
  13. P. Marteau, N. Zanier-Szydlowski, A. Aoufi, G. Hotier, F. Cansell, “Remote Raman spectroscopy for process control,” Fib. Spectrosc. 9, 101–109 (1995).
    [CrossRef]
  14. Z. Y. Zhu, M. C. Yappert, “Determination of effective depth and equivalent pathlength for a single-fiber fluorometric sensor,” Appl. Spectrosc. 46, 912–918 (1992).
    [CrossRef]
  15. Z. Y. Zhu, M. C. Yappert, “Determination of effective depth for double-fiber fluorometric sensors,” Appl. Spectrosc. 46, 919–924 (1992).
    [CrossRef]
  16. S. W. Allison, G. T. Gillies, D. W. Magnusen, T. S. Pagano, “Pulsed laser damage to optical fibers,” Appl. Opt. 24, 3140–3144 (1985).
    [CrossRef] [PubMed]
  17. S. W. Allison, M. R. Cates, G. T. Gillies, B. W. Noel, “Fiber optic pulsed laser delivery for remote measurements,” Opt. Eng. 26, 538–546 (1987).
  18. L. S. Greek, H. G. Schulze, M. W. Blades, A. V. Bree, B. B. Gorzalka, R. F. B. Turner, “SNR enhancement and deconvolution of Raman spectra using a two-point entropy regularization method,” Appl. Spectrosc. 49, 425–431 (1995).
    [CrossRef]
  19. A. Yariv, Quantum Electronics (Wiley, New York, 1992), pp. 75–103.
  20. H. J. Berstein, “Resonance Raman spectra,” in Advances in Raman Spectroscopy, J. P. Mathieu, ed. (Heyden, London, 1973), Chap. 37, pp. 305–316.
  21. P. A. Fodor, T. G. Spiro, “Ultraviolet resonance Raman spectroscopy of DNA with 200–266-nm excitation,” J. Am. Chem. Soc. 108, 3198–3205 (1986).
    [CrossRef]
  22. P. A. Fodor, R. P. Rava, T. R. Hays, T. G. Spiro, “Ultraviolet resonance Raman spectroscopy of the nucleotides with 266-, 240-, 218-, and 200-nm pulsed laser excitation,” J. Am. Chem. Soc. 107, 1520–1529 (1985).
    [CrossRef]
  23. C. R. Johnson, M. Ludwig, S. O’Donnell, s. A. Asher, “UV resonance Raman spectroscopy of the aromatic amino acids and myoglobin,” J. Am. Chem. Soc. 106, 5008–5010 (1984).
    [CrossRef]
  24. S. A. Asher, M. Ludwig, C. R. Johnson, “UV resonance Raman excitation profiles of the aromatic amino acids,” J. Am. Chem. Soc. 108, 3186–3197 (1986).
    [CrossRef]

1995 (3)

1994 (1)

1992 (2)

1991 (1)

1990 (4)

M. L. Myrick, S. M. Angel, R. Desiderio, “Comparison of some fiber optic configurations for measurement of luminescence and Raman scattering,” Appl. Opt. 29, 1333–1344 (1990).
[CrossRef] [PubMed]

M. L. Myrick, S. M. Angel, “Elimination of background in fiber-optic Raman measurements,” Appl. Spectrosc. 44, 565–570 (1990).
[CrossRef]

J. M. Bello, V. A. Narayanan, D. L. Stokes, T. Vo-Dinh, “Fiber-optic remote sensor for in situ surface-enhanced Raman scattering analysis,” Anal. Chem. 62, 2437–2441 (1990).
[CrossRef]

S. M. Angel, M. L. Myrick, “Wavelength selection for fiber optic Raman spectroscopy. Part 1,” Appl. Opt. 9, 1350–1352 (1990).
[CrossRef]

1987 (1)

S. W. Allison, M. R. Cates, G. T. Gillies, B. W. Noel, “Fiber optic pulsed laser delivery for remote measurements,” Opt. Eng. 26, 538–546 (1987).

1986 (4)

S. A. Asher, M. Ludwig, C. R. Johnson, “UV resonance Raman excitation profiles of the aromatic amino acids,” J. Am. Chem. Soc. 108, 3186–3197 (1986).
[CrossRef]

P. Plaza, N. Q. Dao, M. Jouan, H. Fevrier, H. Saisse, “Simulation et optimisation des capteurs a` fibres optiques adjacentes,” Appl. Opt. 25, 3448–3454 (1986).
[CrossRef] [PubMed]

S. D. Schwab, R. L. McCreery, F. T. Gamble, “Normal and resonance Raman spectroelectrochemistry with fiber optic light collection,” Anal. Chem. 58, 2486–2492 (1986).
[CrossRef]

P. A. Fodor, T. G. Spiro, “Ultraviolet resonance Raman spectroscopy of DNA with 200–266-nm excitation,” J. Am. Chem. Soc. 108, 3198–3205 (1986).
[CrossRef]

1985 (2)

P. A. Fodor, R. P. Rava, T. R. Hays, T. G. Spiro, “Ultraviolet resonance Raman spectroscopy of the nucleotides with 266-, 240-, 218-, and 200-nm pulsed laser excitation,” J. Am. Chem. Soc. 107, 1520–1529 (1985).
[CrossRef]

S. W. Allison, G. T. Gillies, D. W. Magnusen, T. S. Pagano, “Pulsed laser damage to optical fibers,” Appl. Opt. 24, 3140–3144 (1985).
[CrossRef] [PubMed]

1984 (2)

C. R. Johnson, M. Ludwig, S. O’Donnell, s. A. Asher, “UV resonance Raman spectroscopy of the aromatic amino acids and myoglobin,” J. Am. Chem. Soc. 106, 5008–5010 (1984).
[CrossRef]

S. D. Schwab, R. L. McCreery, “Versatile, efficient Raman sampling with fiber optics,” Anal. Chem. 56, 2199–2204 (1984).
[CrossRef]

Allison, S. W.

S. W. Allison, M. R. Cates, G. T. Gillies, B. W. Noel, “Fiber optic pulsed laser delivery for remote measurements,” Opt. Eng. 26, 538–546 (1987).

S. W. Allison, G. T. Gillies, D. W. Magnusen, T. S. Pagano, “Pulsed laser damage to optical fibers,” Appl. Opt. 24, 3140–3144 (1985).
[CrossRef] [PubMed]

Angel, S. M.

Aoufi, A.

P. Marteau, N. Zanier-Szydlowski, A. Aoufi, G. Hotier, F. Cansell, “Remote Raman spectroscopy for process control,” Fib. Spectrosc. 9, 101–109 (1995).
[CrossRef]

Asher, S. A.

S. A. Asher, M. Ludwig, C. R. Johnson, “UV resonance Raman excitation profiles of the aromatic amino acids,” J. Am. Chem. Soc. 108, 3186–3197 (1986).
[CrossRef]

C. R. Johnson, M. Ludwig, S. O’Donnell, s. A. Asher, “UV resonance Raman spectroscopy of the aromatic amino acids and myoglobin,” J. Am. Chem. Soc. 106, 5008–5010 (1984).
[CrossRef]

Bello, J. M.

J. M. Bello, V. A. Narayanan, D. L. Stokes, T. Vo-Dinh, “Fiber-optic remote sensor for in situ surface-enhanced Raman scattering analysis,” Anal. Chem. 62, 2437–2441 (1990).
[CrossRef]

Berstein, H. J.

H. J. Berstein, “Resonance Raman spectra,” in Advances in Raman Spectroscopy, J. P. Mathieu, ed. (Heyden, London, 1973), Chap. 37, pp. 305–316.

Blades, M. W.

Bree, A. V.

Cansell, F.

P. Marteau, N. Zanier-Szydlowski, A. Aoufi, G. Hotier, F. Cansell, “Remote Raman spectroscopy for process control,” Fib. Spectrosc. 9, 101–109 (1995).
[CrossRef]

Cates, M. R.

S. W. Allison, M. R. Cates, G. T. Gillies, B. W. Noel, “Fiber optic pulsed laser delivery for remote measurements,” Opt. Eng. 26, 538–546 (1987).

Dao, N. Q.

Desiderio, R.

Fevrier, H.

Fodor, P. A.

P. A. Fodor, T. G. Spiro, “Ultraviolet resonance Raman spectroscopy of DNA with 200–266-nm excitation,” J. Am. Chem. Soc. 108, 3198–3205 (1986).
[CrossRef]

P. A. Fodor, R. P. Rava, T. R. Hays, T. G. Spiro, “Ultraviolet resonance Raman spectroscopy of the nucleotides with 266-, 240-, 218-, and 200-nm pulsed laser excitation,” J. Am. Chem. Soc. 107, 1520–1529 (1985).
[CrossRef]

Gamble, F. T.

S. D. Schwab, R. L. McCreery, F. T. Gamble, “Normal and resonance Raman spectroelectrochemistry with fiber optic light collection,” Anal. Chem. 58, 2486–2492 (1986).
[CrossRef]

Garrison, A. A.

S. W. Kercel, M. J. Roberts, A. A. Garrison, “Recent developments in the development of a fiber-optic based instrument for on-line Raman analysis,” in Raman and Luminescence Spectroscopies in Technology II, F. Adar, J. E. Griffith, eds., Proc. SPIE1336, 144–151 (1990).

Gillies, G. T.

S. W. Allison, M. R. Cates, G. T. Gillies, B. W. Noel, “Fiber optic pulsed laser delivery for remote measurements,” Opt. Eng. 26, 538–546 (1987).

S. W. Allison, G. T. Gillies, D. W. Magnusen, T. S. Pagano, “Pulsed laser damage to optical fibers,” Appl. Opt. 24, 3140–3144 (1985).
[CrossRef] [PubMed]

Goldberg, B. B.

D. Heiman, X. L. Zheng, S. Sprunt, B. B. Goldberg, E. D. Isaacs, “Fiber-optics for spectroscopy,” in Raman Scattering, Luminescence and Spectroscopic Instrumentation in Technology, F. Adar, J. E. Griffiths, J. M. Lerner, eds., Proc. SPIE1055, 96–103 (1989).

Gorzalka, B. B.

Greek, L. S.

Hays, T. R.

P. A. Fodor, R. P. Rava, T. R. Hays, T. G. Spiro, “Ultraviolet resonance Raman spectroscopy of the nucleotides with 266-, 240-, 218-, and 200-nm pulsed laser excitation,” J. Am. Chem. Soc. 107, 1520–1529 (1985).
[CrossRef]

Heiman, D.

D. Heiman, X. L. Zheng, S. Sprunt, B. B. Goldberg, E. D. Isaacs, “Fiber-optics for spectroscopy,” in Raman Scattering, Luminescence and Spectroscopic Instrumentation in Technology, F. Adar, J. E. Griffiths, J. M. Lerner, eds., Proc. SPIE1055, 96–103 (1989).

Hotier, G.

P. Marteau, N. Zanier-Szydlowski, A. Aoufi, G. Hotier, F. Cansell, “Remote Raman spectroscopy for process control,” Fib. Spectrosc. 9, 101–109 (1995).
[CrossRef]

Isaacs, E. D.

D. Heiman, X. L. Zheng, S. Sprunt, B. B. Goldberg, E. D. Isaacs, “Fiber-optics for spectroscopy,” in Raman Scattering, Luminescence and Spectroscopic Instrumentation in Technology, F. Adar, J. E. Griffiths, J. M. Lerner, eds., Proc. SPIE1055, 96–103 (1989).

Jiaying, M.

Johnson, C. R.

S. A. Asher, M. Ludwig, C. R. Johnson, “UV resonance Raman excitation profiles of the aromatic amino acids,” J. Am. Chem. Soc. 108, 3186–3197 (1986).
[CrossRef]

C. R. Johnson, M. Ludwig, S. O’Donnell, s. A. Asher, “UV resonance Raman spectroscopy of the aromatic amino acids and myoglobin,” J. Am. Chem. Soc. 106, 5008–5010 (1984).
[CrossRef]

Jouan, M.

Kercel, S. W.

S. W. Kercel, M. J. Roberts, A. A. Garrison, “Recent developments in the development of a fiber-optic based instrument for on-line Raman analysis,” in Raman and Luminescence Spectroscopies in Technology II, F. Adar, J. E. Griffith, eds., Proc. SPIE1336, 144–151 (1990).

Li, Y.

Lombardi, D. R.

Ludwig, M.

S. A. Asher, M. Ludwig, C. R. Johnson, “UV resonance Raman excitation profiles of the aromatic amino acids,” J. Am. Chem. Soc. 108, 3186–3197 (1986).
[CrossRef]

C. R. Johnson, M. Ludwig, S. O’Donnell, s. A. Asher, “UV resonance Raman spectroscopy of the aromatic amino acids and myoglobin,” J. Am. Chem. Soc. 106, 5008–5010 (1984).
[CrossRef]

Ma, J.

Magnusen, D. W.

Mann, C. K.

Marteau, P.

P. Marteau, N. Zanier-Szydlowski, A. Aoufi, G. Hotier, F. Cansell, “Remote Raman spectroscopy for process control,” Fib. Spectrosc. 9, 101–109 (1995).
[CrossRef]

McCreery, R. L.

S. D. Schwab, R. L. McCreery, F. T. Gamble, “Normal and resonance Raman spectroelectrochemistry with fiber optic light collection,” Anal. Chem. 58, 2486–2492 (1986).
[CrossRef]

S. D. Schwab, R. L. McCreery, “Versatile, efficient Raman sampling with fiber optics,” Anal. Chem. 56, 2199–2204 (1984).
[CrossRef]

Myrick, M. L.

Narayanan, V. A.

J. M. Bello, V. A. Narayanan, D. L. Stokes, T. Vo-Dinh, “Fiber-optic remote sensor for in situ surface-enhanced Raman scattering analysis,” Anal. Chem. 62, 2437–2441 (1990).
[CrossRef]

Noel, B. W.

S. W. Allison, M. R. Cates, G. T. Gillies, B. W. Noel, “Fiber optic pulsed laser delivery for remote measurements,” Opt. Eng. 26, 538–546 (1987).

O’Donnell, S.

C. R. Johnson, M. Ludwig, S. O’Donnell, s. A. Asher, “UV resonance Raman spectroscopy of the aromatic amino acids and myoglobin,” J. Am. Chem. Soc. 106, 5008–5010 (1984).
[CrossRef]

Pagano, T. S.

Plaza, P.

Rava, R. P.

P. A. Fodor, R. P. Rava, T. R. Hays, T. G. Spiro, “Ultraviolet resonance Raman spectroscopy of the nucleotides with 266-, 240-, 218-, and 200-nm pulsed laser excitation,” J. Am. Chem. Soc. 107, 1520–1529 (1985).
[CrossRef]

Roberts, M. J.

S. W. Kercel, M. J. Roberts, A. A. Garrison, “Recent developments in the development of a fiber-optic based instrument for on-line Raman analysis,” in Raman and Luminescence Spectroscopies in Technology II, F. Adar, J. E. Griffith, eds., Proc. SPIE1336, 144–151 (1990).

Saisse, H.

Schulze, H. G.

Schwab, S. D.

S. D. Schwab, R. L. McCreery, F. T. Gamble, “Normal and resonance Raman spectroelectrochemistry with fiber optic light collection,” Anal. Chem. 58, 2486–2492 (1986).
[CrossRef]

S. D. Schwab, R. L. McCreery, “Versatile, efficient Raman sampling with fiber optics,” Anal. Chem. 56, 2199–2204 (1984).
[CrossRef]

Spiro, T. G.

P. A. Fodor, T. G. Spiro, “Ultraviolet resonance Raman spectroscopy of DNA with 200–266-nm excitation,” J. Am. Chem. Soc. 108, 3198–3205 (1986).
[CrossRef]

P. A. Fodor, R. P. Rava, T. R. Hays, T. G. Spiro, “Ultraviolet resonance Raman spectroscopy of the nucleotides with 266-, 240-, 218-, and 200-nm pulsed laser excitation,” J. Am. Chem. Soc. 107, 1520–1529 (1985).
[CrossRef]

Sprunt, S.

D. Heiman, X. L. Zheng, S. Sprunt, B. B. Goldberg, E. D. Isaacs, “Fiber-optics for spectroscopy,” in Raman Scattering, Luminescence and Spectroscopic Instrumentation in Technology, F. Adar, J. E. Griffiths, J. M. Lerner, eds., Proc. SPIE1055, 96–103 (1989).

Stokes, D. L.

J. M. Bello, V. A. Narayanan, D. L. Stokes, T. Vo-Dinh, “Fiber-optic remote sensor for in situ surface-enhanced Raman scattering analysis,” Anal. Chem. 62, 2437–2441 (1990).
[CrossRef]

Turner, R. F. B.

Vickers, T. J.

Vo-Dinh, T.

J. M. Bello, V. A. Narayanan, D. L. Stokes, T. Vo-Dinh, “Fiber-optic remote sensor for in situ surface-enhanced Raman scattering analysis,” Anal. Chem. 62, 2437–2441 (1990).
[CrossRef]

Yappert, M. C.

Yariv, A.

A. Yariv, Quantum Electronics (Wiley, New York, 1992), pp. 75–103.

Zanier-Szydlowski, N.

P. Marteau, N. Zanier-Szydlowski, A. Aoufi, G. Hotier, F. Cansell, “Remote Raman spectroscopy for process control,” Fib. Spectrosc. 9, 101–109 (1995).
[CrossRef]

Zheng, X. L.

D. Heiman, X. L. Zheng, S. Sprunt, B. B. Goldberg, E. D. Isaacs, “Fiber-optics for spectroscopy,” in Raman Scattering, Luminescence and Spectroscopic Instrumentation in Technology, F. Adar, J. E. Griffiths, J. M. Lerner, eds., Proc. SPIE1055, 96–103 (1989).

Zhong, L.

Zhu, Z. Y.

Anal. Chem. (3)

S. D. Schwab, R. L. McCreery, “Versatile, efficient Raman sampling with fiber optics,” Anal. Chem. 56, 2199–2204 (1984).
[CrossRef]

S. D. Schwab, R. L. McCreery, F. T. Gamble, “Normal and resonance Raman spectroelectrochemistry with fiber optic light collection,” Anal. Chem. 58, 2486–2492 (1986).
[CrossRef]

J. M. Bello, V. A. Narayanan, D. L. Stokes, T. Vo-Dinh, “Fiber-optic remote sensor for in situ surface-enhanced Raman scattering analysis,” Anal. Chem. 62, 2437–2441 (1990).
[CrossRef]

Appl. Opt. (4)

Appl. Spectrosc. (7)

Fib. Spectrosc. (1)

P. Marteau, N. Zanier-Szydlowski, A. Aoufi, G. Hotier, F. Cansell, “Remote Raman spectroscopy for process control,” Fib. Spectrosc. 9, 101–109 (1995).
[CrossRef]

J. Am. Chem. Soc. (4)

P. A. Fodor, T. G. Spiro, “Ultraviolet resonance Raman spectroscopy of DNA with 200–266-nm excitation,” J. Am. Chem. Soc. 108, 3198–3205 (1986).
[CrossRef]

P. A. Fodor, R. P. Rava, T. R. Hays, T. G. Spiro, “Ultraviolet resonance Raman spectroscopy of the nucleotides with 266-, 240-, 218-, and 200-nm pulsed laser excitation,” J. Am. Chem. Soc. 107, 1520–1529 (1985).
[CrossRef]

C. R. Johnson, M. Ludwig, S. O’Donnell, s. A. Asher, “UV resonance Raman spectroscopy of the aromatic amino acids and myoglobin,” J. Am. Chem. Soc. 106, 5008–5010 (1984).
[CrossRef]

S. A. Asher, M. Ludwig, C. R. Johnson, “UV resonance Raman excitation profiles of the aromatic amino acids,” J. Am. Chem. Soc. 108, 3186–3197 (1986).
[CrossRef]

Opt. Eng. (1)

S. W. Allison, M. R. Cates, G. T. Gillies, B. W. Noel, “Fiber optic pulsed laser delivery for remote measurements,” Opt. Eng. 26, 538–546 (1987).

Other (4)

S. W. Kercel, M. J. Roberts, A. A. Garrison, “Recent developments in the development of a fiber-optic based instrument for on-line Raman analysis,” in Raman and Luminescence Spectroscopies in Technology II, F. Adar, J. E. Griffith, eds., Proc. SPIE1336, 144–151 (1990).

D. Heiman, X. L. Zheng, S. Sprunt, B. B. Goldberg, E. D. Isaacs, “Fiber-optics for spectroscopy,” in Raman Scattering, Luminescence and Spectroscopic Instrumentation in Technology, F. Adar, J. E. Griffiths, J. M. Lerner, eds., Proc. SPIE1055, 96–103 (1989).

A. Yariv, Quantum Electronics (Wiley, New York, 1992), pp. 75–103.

H. J. Berstein, “Resonance Raman spectra,” in Advances in Raman Spectroscopy, J. P. Mathieu, ed. (Heyden, London, 1973), Chap. 37, pp. 305–316.

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Figures (10)

Fig. 1
Fig. 1

Diagrammatic representation of the excitation and the collection processes in fiber-optic RRS.

Fig. 2
Fig. 2

Demonstration of different path lengths and angles possible when scattering from a particular volume element to the collection surface and the need for integration over all area elements on the collection surface.

Fig. 3
Fig. 3

Diagram of the Raman system used in these investigations. Three different excitation schemes were used: A, for pulsed 266 nm; B, for pulsed 225 nm; C, for cw 472.7 nm. BBO X’tal (β barium borate crystal).

Fig. 4
Fig. 4

Typical spectrum of a mixture of MO and NO3 showing the peak positions and the subtracted backgrounds.

Fig. 5
Fig. 5

Experimental and modeled working curves for methyl orange. Squares, probe E; triangles, probe C; circles, probe A. The filled symbols are experimental data, and the open symbols are modeled data.

Fig. 6
Fig. 6

Plot of NO3 signal strength versus MO concentration showing reduction in probe sensitivity with increasing medium absorbence. Squares, probe E; triangles, probe C; circles, probe A. The filled symbols are experimental data, and the open symbols are modeled data.

Fig. 7
Fig. 7

Circles, Working curve for MO (1400-cm−1 peak height versus MO) and a 200-μm diameter, 45° angled excitation–200-μm diameter collection, fiber probe. Squares, height of 0.153 M NO3 versus MO. Inset, probe-tip diagram.

Fig. 8
Fig. 8

266-nm (10-Hz, 10-ns pulses) UV resonance Raman spectrum of 50-μg/ml salmon DNA obtained with probe C. The exposure time was 8.8 min, the average power at the sample was approximately 1 mW, and the slit width was 500 μm. The letter over each peak denotes the base that gives rise to the peaks (C, cytosine; A, adenine; G, guanine; T, thymine; see ref. 21). The peak near 1050 cm−1 is due to nitrate, which was added as an internal standard and calibrant.

Fig. 9
Fig. 9

Pulsed (10-Hz, 10-ns) UV (225-nm) resonance Raman spectrum of the amino acid tryptophan obtained with probe H. The exposure time was 10 min, the average power at the sample was approximately 200 μW, and the slit width was 300 μm.

Fig. 10
Fig. 10

Partial working curve for DNA obtained with 266-nm excitation and probe C. The 1484-cm−1 peak was used as the signal.

Tables (1)

Tables Icon

Table 1 Geometry and Performance of Probes Used in These Studies

Equations (8)

Equations on this page are rendered with MathJax. Learn more.

θ acceptance = sin 1 ( NA ) = sin 1 [ ( n co 2 n cl 2 ) 1 / 2 n m ] ,
F ( x , y , z ) = A ( z ) EX ( θ ) 10 l e ( e c + a m e ) R e 2 r e 2 ( z ) ,
d E RS = F ( x e , y e , z e ) σ v c d V e ,
d ( d E c ) = COL ( α ) d A c d E RS 10 l c ( c c + a m c ) cos ( α ) 4 π l c 2 ,
d E c = fiber surface d ( d E c ) .
E c = volume of overlap d E c .
E c = volume of overlap collection surface × COL ( α ) cos ( α ) F ( x e , y e , z e ) σ ν c 10 l c ( c c + a m c ) 4 π l c 2 d A c d V e ,
E c = vol . of overlap collection surface × COL ( α ) cos ( α ) F ( x e , y e , z e ) σ ν c 10 l c ( c c + a m c ) 4 π l c 2 Δ A c Δ V ,

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