Currently we are plan to study the optical property of nanoparticles. So i request you confirm both studies UV-VIS and UV-DRS are same or different. If both studies are same than the studies applicable only for.thin films or powder samples. If it is possible for powder sample how to measure the thickness of the powder sample for calculating the absorption.
UV-VIS most often refers to absorption spectroscopy, measured by transmission, whereas DRS specifically refers to diffuse reflection spectroscopy.
Normally, the former is used for solutions/suspensions or thin films, whereas the latter is used for solids - optically rough films or powders.
Absorption is usually defined per unit thickness, for a solid of well defined density, or by concentration, for a particulate or molecular material in suspension or solution.
How best to measure a powder depends on what type of powder and how you can process it.
UV-VIS most often refers to absorption spectroscopy, measured by transmission, whereas DRS specifically refers to diffuse reflection spectroscopy.
Normally, the former is used for solutions/suspensions or thin films, whereas the latter is used for solids - optically rough films or powders.
Absorption is usually defined per unit thickness, for a solid of well defined density, or by concentration, for a particulate or molecular material in suspension or solution.
How best to measure a powder depends on what type of powder and how you can process it.
Check the link
http://chemistry.stackexchange.com/questions/6091/what-is-the-principle-of-diffuse-reflectance-spectroscopy-behind-band-gap-measur
Dear Rajesh,
As Dr. Hugh explained, the UV-Vis spectroscopy refers the abosrption or transmission spectra. In general, DRS refers to diffuse refrection spectra (spectroscopy). To make the difference more precise, I would like to add:
1. By UV-Vis, we refer just the UV and Vissible spectral range. DRS can also be measured in this range.
2. Generally in UV-Vis spectroscopy we record absroption or transmission spectrun in VU-Vis range for normal (or close to normal) incidence. As this technique is used to characterise samples in thin film form or in liquid form, where there is not much dispersion, the angle of incidence = angle of reflection, i.e. the refrection is specular.
3. In the case of granular/powder or thin films of high surface roughness, the reflection is not specular (although for each incident photon, the reflection is specular), and hence we can not measure the transmitted intensity (it is too low) to get the absorption of the sample as in case of specular case.
Therefore, for powders or thin films of high surface roughness, we use DRS where apart from recording rrefreclance, we can also measure absorbance of the sample collecting all the diffuses reflected beams (from the sample surface) using a semispherical collector.
For detailed analysis of DRS of powder samples, you can follow the aricle Revista Mexicana de Fisica S 53 (5) (2007)18. It is available online too.
Can Uv-visible diffuse reflectance spectroscopy measures directly the band gap of amorphous silicon solar cell
Why absorption and reflectance are not complementing each other Some time?
As Dr. Hugh explained, the UV-Vis spectroscopy refers the abosrption or transmission spectra. In general, DRS refers to diffuse refrection spectra (spectroscopy). To make the difference more precise, I would like to add:
1. By UV-Vis, we refer just the UV and Vissible spectral range. DRS can also be measured in this range.
2. Generally in UV-Vis spectroscopy we record absroption or transmission spectrun in VU-Vis range for normal (or close to normal) incidence. As this technique is used to characterise samples in thin film form or in liquid form, where there is not much dispersion, the angle of incidence = angle of reflection, i.e. the refrection is specular.
3. In the case of granular/powder or thin films of high surface roughness, the reflection is not specular (although for each incident photon, the reflection is specular), and hence we can not measure the transmitted intensity (it is too low) to get the absorption of the sample as in case of specular case.
Therefore, for powders or thin films of high surface roughness, we use DRS where apart from recording rrefreclance, we can also measure absorbance of the sample collecting all the diffuses reflected beams (from the sample surface) using a semispherical collector
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