Electromagnetic enhancement modification

It is likely that the decreases observed can be rationalized in terms of two contributions. Changes in surface optical properties resulting from modification by the foreign metal have been shown to decrease the electromagnetic enhancement contribution to SERS. However, for the case of Pb UPD on Ag, this effect has been shown to account for only ca. 40% of the decrease in going from zero coverage to one monolayer.(14) Moreover, this model does not account for the relatively rapid decrease in intensity observed with the deposition of small (i.e., less than 20% of a monolayer) amounts of Pb on the Ag surface. 

The directional properties of the local field electromagnetic enhancement have been used to deduce the orientation of small molecules adsorbed on Ag colloids and electrodes. Moskovits and Suh and Creighton "" used these properties to deduce surface selection rules, which essentially are the modifications of band intensities due to the normal and tangential enhancement components of the local field of a molecule near a metal surface. Here the... 

Physical. Anecdotal accounts abound of enhanced plant resistance to disease achieved by transient exposure to a wide variety of physical stimuli, e.g., heat, light, microwaves, other electromagnetic radiation, electric current, sound waves, and vibration. In our own laboratory, we have made cucumbers resistant to anthracnose by vibration (Stromberg and Kuc, unpublished). However, these phenomena are poorly understood and may include enhanced resistance resulting from non-specific altered (stress) physiology, nonspecific phytoalexin elicitation, modification of the action of gene products, or sensitization. This interesting but little explored area will not be further discussed in this paper. 

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