Question $3$

$[28$ Marks$]$

$3\mathrm{.}1.$ Raman spectroscopy is widely used to analyse the vibrational modes of materials. In graphene, Raman spectroscopy can provide information about the number of graphene layers $($for example, distinguishing between monolayer, bilayer, and few$-$layer graphene$),$ the presence of defects $($such as vacancies or substitutions$),$ and the strain in the graphene lattice. The Raman spectrum of graphene typically includes peaks like the $G$ band $($associated with in$-$plane bond stretching$),$ the $2$D band $($related to two$-$phonon double resonance processes$),$ and the D band $($indicating defects or disorder$).$ Use Figure $2$ below to identify the G$-$band and $2$D$-$ band for

$($a$)$ Graphite.

$(2)$

$($b$)$ Single layer graphene.

$(2)$

$4$