Q2 Useful Equations d(H)=3DkTVR=2a2exp(kD)VA=A/(12D2) (i) A colloidal suspension of spherical gold nanoparticles exhibits a deep red colour. What small particle effect is responsible for this colour? Clearly define this effect. (2 marks) (ii) Discuss how the small particle effect for spherical particles defined in part (i) varies for rod shaped gold nanoparticles with respect to the ground state absorption. (6 marks) (iii) Briefly describe how DLS can be used to measure the average particle size of the spherical gold nanoparticle colloid. Make specific reference to Brownian motion, the hydrodynamic radius, intensity correlation and cumulant analysis