Damping factor, transition metal

Effect of Other Modes. In most transition metal and organometallic compounds, many modes are displaced. If one mode is highly displaced and other vibrational modes have small displacements in the excited state, the modes with small displacement act as a damping factor to fill in the spectra. When six modes with small displacements are added to the model calculation and the damping factor is kept the same, the resulting spectra with the six... 

Certainly the clearest conclusion from the examples of this chapter is the total absence of sharp features in the inelastic response function of anomalous lanthanide and metallic actinide materials. This contrasts strongly with the sharp dispersionless crystal-field excitations observed in most lanthanide compounds, in which the exchange interactions are weak (fig, 2), and with the sharp spin-wave excitations found in systems with strong exchange interactions. In many of the early studies with neutron inelastic scattering, for example of the heavy lanthanides or transition metals and their compounds, the width of the excitations was never an issue. It was almost always limited by the instrumental resolution, although it should be stressed that this resolution is relatively poor compared to that obtained by optical techniques. However, the situation is completely different in the materials discussed in this chapter. Now the dominant factor is often the width indeed in some materials the width of the over-damped response function is almost the only remaining parameter with which to characterize the response. 

Additional resonance enhancement can be achieved for adsorbed chromophore molecules when excitation wavelength coincides with both LSPR and an allowed molecular electronic transition of adsorbate. This phenomenon is called surface-enhanced resonance Raman scattering (SERRS). Although RRS/NRS enhancement about 10 -10 can be reached, SERRS/RRS factor is only 10 -10 due to additional damping of molecular resonance for chromophore molecules adsorbed on metal surface (Weitz et al. 1983). 

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