  A phenomenological approach to the stretching mode vibrational frequencies of
defects in semiconductors is proposed. A novel quantum scale is defined in
terms of the first principles pseudopotential based orbital radius and the
principal quantum number of the element concerned. A universal linear
relationship between the Sanderson electronegativity and this quantum scale is
established. Next, we show that the stretching mode vibrational frequencies of
hydrogen and chlorine in the silicon network scale linearly with this quantum
scale. Predictions and identifications of defect environments around the Si-H
and Si-Cl are possible. The assignments of vibrational modes in porous silicon
are critically examined. We discuss our proposed scale in the context of
Mendeleveyan scales in general, and suggest justifications for it. We believe
that our approach can be gainfully extended to the vibrational spectra of other
semiconductors.
