Will any body solve the problem that how I am sure about DLS spectra showed below 1nm of CdS nano-particle by further investigation or by instrumentation?
Hi, not sure I fully understand your question, but if you have access to TEM or even SAXS, that should give you complementary information. Moreover, the size you get by DLS is a hydrodynamic radius, and 1 nm sure sounds quite small! Are you sure about that?
DLS should be able to measure qunatum dots [ see for example http://www.materials-talks.com/blog/2014/11/17/tips-tricks-for-nanoparticle-characterization/#qdots ] however your system may require a narrow band filter option. This is discussed at http://www.materials-talks.com/blog/2016/03/03/what-is-a-narrow-band-filter/
Below 1nm is small, and you should check the quality of the correlation function, specficially the intercept, as you may only be looking at noise.
1 nm ??
-mm I don't think any instrument (except for HR-TEM) (any kind of spectroscopy or chemical analisys method can have the capability/resolution) of such quantumlly minuscule scale.
- 1 nm is equals to 10 Angströms , the Cd atom radius is about 1.5 Angströms
- and the distance between between two continuous Cd atoms in the z direction of the unit cell on the Hexagonal CdS wurtzite structure is 4 Angströms (you can download the software VESTA to familiarize with these scales).
so getting back on the subject ,
the Bohr Radius of the CdS is between 17 and 20 nms , so yes in theory you would have QDs , since 1nm < 2*a0 .
But, I'm sure there is something wrong with the characterizations, 1 nm is not many times well conceivable, at least we would talking about High Resolution TEM characterizations.
I don't know if I can say that Ellipsometry could give you good results at this scale, in theory yes, since in theory it has the capability to measure thin film's thicknesses at the level of Angströms, but since this techniques depends on the imput of mathematical models and some by-hand known optical parameters, I doubt it too.
Regards !
Sometimes due to multiple scattering in a sample, we get a smaller particle size than actual. You should also check that. Multiple scattering occurs as a result of high concentration of sample.
Experts please correct me if im wrong.
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