SERS Experimental Studies

In this section we discuss in a critical manner the experimental evidence accumulated. Discussion of possible enhancement mechanisms will be given only in a later section, so that separation of facts and interpretation, can, as much as possible, be made. 

Silver, being the most widely studied metal in the context of SERS, will play the leading role also in this section and in the entire review. Nevertheless, other metals and substrates will also be discussed. The other leading part is played by pyridine—the telltale molecule of SERS. Other molecules will also be discussed, a few in some detail, to introduce new or important behavior not shown by pyridine, or to substantiate some evidence for mechanisms of SERS. 

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Hartl, M., Kfupka, I., and LiSka, M., Experimental Study of Boundary Layers Formation by Thin Film Colorimetric Interferometry," Sci. China, Ser. A Math., Phys., Astron. Technol. Sci.,Vol. 44(supp), 2001,pp. 412-417. 

Lefuma J, Chameaud J, Perraud R, et al. 1976. [An experimental study on a comparison between the toxic effects of radon-222 and its daughters on the lungs, and those exerted by alpha-emitters of the actinium series.] Occup Saf Health Ser 32 43-53. (French). 

Sudo, Y., T. Usui, and M. Kaminaga, 1991, Experimental Study of Falling Water Limitation under a Counter-current Flow in a Vertical Rectangular Channel, JSMEInt. J. Ser. H 34 169-174. (5) Sugawara, S., 1990, Analytical Prediction of CHF by FIDAS Code Based on Three-Fluid and Film-Dryout Model, J. Nuclear Sci. Technol. 27. 12 29. (5)... 

Guary, J.C. and S.W. Fowler. 1990. Experimental study of the transfer of transuranium nuclides in marine decapod crustaceans. Mar. Ecol. Prog. Ser. 60 253-270. 

Kelly, 3.R. and Nixon, S.W., 1984. Experimental studies of the effect of organic deposition on the metabolism of a coastal marine bottom community. Mar. Ecol. Prog. Ser., 17 (2) 157-169. 

Rice, D.L., Bianchi, T.S., and Roper, E. (1986) Experimental studies of sediment reworking and growth of Scoloplos spp (Orbiniidae Polychaeta). Mar. Ecol. Prog. Ser. 30, 9-19. 

Tomasko, D.A., and Lapointe, B.E. (1991) Productivity and biomass of Thalassia testudinum as related to water column nutrient availability and epiphyte levels field observations and experimental studies. Mar. Ecol. Prog. Ser. 75 9-17. 

Only a very few experimental studies have been made for detection of multiplicities of steady states to check on theoretical predictions. The studies of multiplicities and of oscillations of concentrations have similar mathematical bases. Comprehensive reviews of these topics are by Schmitz Adv. Chem. Ser., 148, 156, ACS [1975]), Razon and Schmitz Chem. Eng. Sci., 42, 1,005-1,047 [1987]), Morbidelli, Varma, and Arts (in Carberry and Varma, eds.. Chemical ReacUonand ReactorEn neering, Dekker, 1987, pp. 975-1,054). 

In this chapter on SERS hot spots, 1 will cover recent results of both theoretical and experimental studies approach. The review will be spht into the following sections ... 

The polar cavity of Asp-102 also includes two buried water molecules, as well as backbone amides of Ala-56 and His-57. In about 200 SP, all but three have this Ser-214 residue. It is solvent inaccessible, and its OG forms a hydrogen bond to Asp-102. In an extensive experimental study by McGrath et al.(1992), Ser-214 has been mutated to Ala, Glu and Lys in rat anionic trypsin and both kinetics and crystallography were employed to study the... 

Vejtasa, S.A. Schmitz, R.A. An experimental study of steady state multiplicity and stability in an adiabatic stirred reactor. AIChE J. 1970,16, 410 19. Schmitz, R.A. Multiplicity, stability, and sensitivity of states in chemically reacting systems - a review. Adv. Chem. Ser. 1975, 148, 156-211. Razon, L.F. Schmitz, R.-A. Multiplicities and instabilities in chemically reacting systems - a review. Chem. Eng. Sci. 1987, 42, 1005-1047. Uppal, A. Ray, W.H. Poore, A.B. On the dynamic behavior of continuous stirred tank reactors. Chem. Eng. Sci. 1974, 29, 967-985. 

In Section II it was shown that there is a large number of experimental studies of SERS phenomena. It is not surprising that there is also an abundance of theoretical models proposed to explain these results. Several excellent reviewsand, in addition, some more specific papers (see, e.g.. Refs. 21-23) have been published. The reader is referred to them for a more complete and rigorous presentation, or for a different point of view. The aim here is to present the theories in as simple terms as possible in order to facilitate comparison of their predictions with the experimental evidence. Also, an attempt is made to point out the strengths of each model and its limitations. 

Moskalev JI, Buldakov LA, Lyaginskaya AM, et al. 1969. Experimental study of radionuclide transfer through the placenta and their biological action on the fetus. AEC Symp Ser 17 153-160. 

There is a direct association between the extent of exposure to aflatoxins in the diet and the prevalence of codon 249 Arg to Ser mutation. The most plausible interpretation of this association is that aflatoxins directly induce these mutations. This interpretation is supported by experimental studies showing that aflatoxin B1 binds at this codon and, preferentially induces this hotspot mutation in human cells in vitro. Moreover, the 249 Arg to Ser mutation is detected in the normal liver of aflatoxin-exposed individuals (Aguilar et al., 1993, 1994). 

Table 4.1 summarizes the variation of the enhancement factor of the Cu4-pyridine complex relative to an isolated pyridine molecule as a function of closest N-Cu distance. The applied frequency for both the Cu4-pyridine complex and the pyridine molecule here is 2.81 eV (same as in Fig. 4.13), which corresponds to the resonant peak associated with the lowest energy state of the CU4 cluster. This frequency is higher than would be appropriate for experimental studies of SERS on Cu nanoparticles, but this is one of the problems associated with using a small cluster instead of a nanoparticle. The results show that for a fixed closest N-Cu distance, the enhancement factor is different for different vibrational modes, and for the same vibrational mode, the enhancement factor... 

L. B. Evans and N. E. Stefany, An Experimental Study of Transient Heat Transfer in Cylindrical Enclosures, Chem. Eng. Prog. Symp. Ser. (62/64) 209-215,1960. 

Shimizu N, Kushiro I (1984) Self-diffusion of silicon and oxygen in silicate melts An experimental study. Springer Ser Chem Phys 36 469-70... 

The solvent-induced stereochemical behaviour of a bile acid-based biphenyl phosphite has been studied experimentally using circular dichroism (CD) spectroscopy, and theoretically using DFT quantum mechanical methods. " The FTIR, Raman and surface-enhanced Raman scattering (SERS) spectra of phenyl phosphate disodium salt have been recorded and its vibrational wavenumbers, calculated using the Hartree-Fock/6-31G basis set, compared with experimental values. From SERS spectra study, the molecule is adsorbed on the silver surface with the benzene ring in a tilted orientation. The presence of the phenyl ring and the phosphate group vibrations in the SERS spectrum reveal the interactions between the phenyl... 

Sparganothis pilleriana (Lepidoptera Tortricidae). Pflanzenschutzberichte, 40, 1-9. Salt, G. (1934) Experimental studies in insect parasitism. II. Superparasitism. Proc. R. Soc. Lond. Ser. B, 114, 455-76. 

The spectra of aromatic amino acids and histidine were first reported by Nabiev et al. [85]. The spectra of other amino acids and short peptides adsorbed on silver electrode or silver vere also later published (see Table 5). However, the spectra of the same amino acids published by various authors showed fairly large variations in relative band intensities and frequencies. The quality of SERS spectra depends on many factors, such as the method of preparation and degree of aggregation of the colloids, pH of medium, concentration of adsorbate, etc. [83]. In view of the facts mentioned above, conditions need to be carefully controlled in order to obtain reproducible results. As the description of experimental conditions published to date is rather poor, it is difficult to explain the observed difference. The common features deduced from the SERS spectroscopic studies of amino acids are as follows ... 

Samoilovich, D. C. 1986. Experimental Study of Sluny Pumps Performances (in Russian). Moscow CINTIchitimeftemash, ser.XM-4. 

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