Dear colleague, generally we should match the wavelenght of the exciting light source for the sample and material which we want to study. Yes, the shorter the wavelenght is the higher is the scattering intensity (~ omega^4). And yes, the shorter the wavelenght is the higher is the probability to excite unwanted luminescence. And don`t forget possible resonance effects. In the case of solid states you should take into account one additional point. The absorption depends also on the wavelength. The shorter the wavelength is the smaller is the penetration depth of the light into the sample, i. e. the smaller is the information depth. If you want to study thin layers on a substrate you should choose a short wavelength. If you want to study bulk properties you need a more larger wavelenght. And finally you have to check the characteristics of your measurement system, i. e. the optimum range of optics, gratings, detectors etc. Wkr, M. Herms.