with a CCD array to produce Raman spectra with good S/N ratios. Although the fluorescence rejection at 783 nm or 633 nm will not be as good as at 1064 nm, a large gain in sensitivity relative to 1064-nm excitation results from the characteristics of the detector. In gen eral, detection limits degrade with in creasing laser wavelength, and a sharp loss of S/N ratio occurs when shot noise limited detection is no longer possible. In contrast, fluorescence (and photolytic damage) becomes less likely with increasing wavelength. Thus the user faces a trade-off between sensitivity and fluorescence rejection, with the choice depending on the application. The work described here was supported by the Chemical Analysis Section of the National Science Foundation. References (1) Alkire, R. C. New Horizons in Electro chemical Science and Technology; Na tional Academy Press: Washington, DC, 1986; NMAB Publication 438-1. (2) McCreery, R. L. Prog. Anal. Spectrosc. 1988,11,141. (3) Bard, A. J.; Faulkner, L. R.; Electro chemical Methods; John Wiley and Sons: New York, 1980. (4) Kissinger, P. T.; Heineman, W. R., Eds. Laboratory Techniques in Electroanalytical Chemistry; Marcel Dekker: New York, 1984. (5) Hawley, M. D.; Tatawawadi, S. V.; Pierkarski, S.; Adams, R. N. J. Am. Chem. Soc. 1967,89, 447. (6) Hawley, M. D.; Feldberg, S. W. J. Phys. Chem. 1966, 70,3459. (7) Adams, R. N.; Hawley, M. D.; Feldberg, S. W. J. Phys. Chem. 1967, 71, 851. (8) Heineman, W. R.; Hawkridge, F. M; Blount, H. N. In Electroanalytical Chem istry; Bard, A. J., Ed.; Marcel Dekker: New York, 1983; Vol. 13. (9) Kuwana, T.; Winograd, N. In Electroanalytical Chemistry; Bard, A. J., Ed.; Marcel Dekker: New York, 1974; Vol. 7. (10) Heineman, W. R. Anal Chem. 1978,50, 390 A. (11) McCreery, R. L. In Physical Methods of Chemistry, Vol. 2: Electrochemical Methods; Bryant Rossiter, Ed.; John Wi ley and Sons: New York, 1986; Chapter 7. (12) Spectroelectrochemistry, Theory and Practice; Gale, R. J., Ed.; Plenum Press: New York, 1988. (13) Jeanmaire, D. L.; Van Duyne, R. P. J. Electroanal. Chem. 1975,66, 235. (14) Jeanmaire, D. L.; Suchanski, M. R.; Van Duyne, R. P. J. Am. Chem. Soc. 1975, 97 1699. (15) Van Duyne, R. P.; Haushalter, J. P. J. Phys. Chem. 1984,88, 2446. (16) Schwab, S. D.; McCreery, R. L.; Gam ble, F. T. Anal. Chem. 1986,58,2486. (17) Packard, P. T.; McCreery, R. L. J. Phys. Chem. 1988,92,6345. (18) Packard, R. T. Ph.D. Dissertation, The Ohio State University, 1988. (19) Van Duyne, R. P. J. Phys. (Paris), Colloq. 1977,38. C5-239-252. (20) Suchanski, M. R.; Van Duyne, R. P. J. Am. Chem. Soc. 1976,98, 250. (21) Cotton, T. M.; Parks, K. D.; Van Duyne, R. P. J. Am. Chem. Soc. 1980,102, 6399. (22) Packard, R. T.; McCreery, R. L. Anal. Chem. 1987,59. 2631.
(23) Van Duyne, R. P. In Chemical and Biological Applications of Lasers; Moore, L. B., Ed.; Academic: New York, 1979; Vol. 4, Chapter 4. (24) Campion, Α.; Brown, J.; Grizzle, W. M. Surf. Sci. 1982,115. L153. (25) "In-situ Characterization of Electro chemical Processes"; report of the Na tional Materials Advisory Board, publica tion NMAB 438-3; National Academy Press: Washington, DC, 1987, Larry Faulkner, Chairman. (26) Birke, R.; Lombardi, J. In Spectroelec trochemistry, Theory and Practice; Gale, R. J., Ed.; Plenum Press: New York, 1988. (27) Garrell, R. Anal. Chem. 1989, 61, 401 A. (28) Van Duyne, R. P. et al. J. Am. Chem. Soc. 1982,104,6528. (29) Bowling, R.; Packard, R.; McCreery, R. L. J. Electrochem. Soc. 1988,135,1605. (30) Bowling, R.; Packard, R.; McCreery, R. L. J. Am. Chem. Soc. 1989, HI, 1217. (31) Chase, D. B. J. Am. Chem. Soc. 1986, 108, 7485. (32) Chase, D. B. Anal. Chem. 1987, 59, 881 A. (33) Lewis, E. N.; Kalasinsky, V. F.; Levin, I. W. Anal. Chem. 1988,60, 2306. (34) Desilvestro, J.; Corrigan, D. Α.; Weaver, M. J. J. Electrochem. Soc. 1988, 135,885. (35) Golab, J. T.; Sprague, J. R.; Carron, K. T.; Schatz, G. C; Van Duyne, R. P. J. Chem. Phys. 1988,88,7942. (36) Chase, D. B.; Parkinson, D. A. Appl. Spectrosc. 1988,42,1186. (37) Angel, S. M.; Katz, L. F.; Archibold, D. D.; Lin, L. T.; Honigs, D. E. Appl. Spectrosc. 1988,42,1327. (38) Williamson, J. M.; Bowling, R.; McCreery, R. L. Appl. Spectrosc. 1989, 43, 372. (39) Pemberton, J. E.; Sobocinski, R. L. J. Am. Chem. Soc. 1989, 111, 432.
Richard L. McCreery joined the fac ulty of The Ohio State University in 1974, where he is currently professor of chemistry. He received his B.S. degree in chemistry at the University of Cali fornia, Riverside, and his Ph.D. in an alytical chemistry at the University of Kansas, where he worked under the direction of Ralph N. Adams. McCreery's research interests include electroanalytical chemistry, electrocatalysis, and spectroscopic probes of electrochemical processes. Of particu lar interest is Raman spectroscopy ap plied to dynamic electrochemical events. Richard T. Packard is a develop ment chemist with E. I. du Pont de Nemours and Co. at Jackson Labora tory, Deepwater, NJ. He received his B.S. degree from Kansas Wesleyan University (Salina) in 1983 and a Ph.D. in analytical chemistry from The Ohio State University in 1988. His research interests include the applica tion of novel sampling techniques to spectroscopic methods development and new detection strategies for pro cess control.
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