The amplitude mode in the presence of disorder and its observation in trans-(Ch)_x, by raman scattering

The shifts of first- and second-order Raman lines in rrons-(CH)_x with laser frequencies are investigated. The Raman vibrations are described in terms of amplitude modes and their overtones due to the Peierls gap in a one-dimensional model. Disorder is included in the model in the form of a random field which gives rise to a domain-like ground state with an effective distribition of the Peierls gaps. Each laser frequency excites a different domain with a different amplitude mode. First- and second-order resonant Raman scattering experiments are performed for trans-(CH)_x,. The second-order lines are convolutions of the firstorder lines.