Executive Summary : | The research aims to understand the role of acoustic phonons in Fano interaction using Raman spectroscopy. Acoustic phonons are present in solids but do not appear in Raman scattering signals due to selection rules. However, at nanoscales, this restriction is relaxed, allowing them to participate in Raman scattering. Raman spectroscopy has been conducted and low frequency Raman spectroscopy has been reported. In-depth analysis of Raman line-shapes and causes affecting the Raman line-shape is not well reported, but it may have subtle physics encapsulated inside the low frequency Raman spectra. Understanding how LF phonon- electronic interaction, similar to Fano resonance between optic phonon-electron, can take place and manifest in the Raman spectrum is crucial. Fano interaction between optic phonons and the electronic continuum can be seen if the width of the continuum is more than the phonon energy. Acoustic phonons, having energies lower than optic phonons, by default fulfill these criteria. The Fano effect resulting due to acoustic phonon-electron interaction is technically possible, but reports are limited and need further investigation. The study will investigate the effect of size and the threshold value of size at the onset of this effect, as it occurs only at the nanoscale. Excitation wavelength dependent low frequency Raman scattering measurements will be a must-do experiment to establish the reasoning behind the observation. A theoretical framework should be developed to explain these observations for a clearer understanding of these subtle physics. |