Second excited states , metal-enhanced

The additional enhancement provided by coadsorbed halide ions on a colloidal silver surface has been pointed out [401]. As an explanation, morphological changes effected by the strongly adsorbed anions have been invoked. The photo-driven CT that is assumed to proceed from filled metal states near the Fermi level of the metal to the first and second excited state in the case of pyrazine adsorbed on polycrystalline gold has been invoked as the cause for the breakdown of Raman selection rules upon adsorption (i.e. the activation of originally Raman-forbidden vibrational modes) [314]. 

Exploiting the enhanced reactivity of Ca often requires the use of two tunable dye lasers (Fig. 2), one to excite the metal atoms to the metastable 3F1 state and the second to detect the product molecules. (Excited metal atoms can also be produced in an electrical discharge or in a laser-vaporized plume.) The two laser beams are introduced into the Broida oven chamber... 

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