Hello Bhaskara Rao Tadiboina

There are concepts that usually make us confused. Usually, DRS sample holder for solids don't let any light trespassing through it. All the incident light in the sample will be either absorbed or reflected. And this reflection of the light, which is not perfectly oriented, is called DIFFUSE REFLECTANCE, which means it goes to all directions. The purpose of the this measure is to integrate all the light that is diffusely reflected. Once you integrate all the light diffused, by consequence, you can know what was the light absorbed by sample. So, there two "graphs" you can generate, one is the light absorbed, and other is the total diffused reflection.

It's not about if "Solid UV spectrum" and "UV-DRS" are different or equal, it depends on the tools you have. I think that DRS can only be used with an integration sphere, that is used to integrate all the light that was reflected by the sample. Yet, a measure of a solid sample can still be used with other tools. Eg: You have some thin film deposited in a glass, and your UV spectrometer has a sample holder for a glass material. Which means that the light will pass through the glass and hit the detector. This not a DRS measure, it is a transmittance measure in a solid thin film. So, you have to be sure what kind of properties you want to measure, to ensure you have the right experiment.

Feel free to reply if you need help

Best regards,

Dr. Ricardo Tadeu.