When we synthesize long nanostructures like ZnO or CdS nanowires, how can we calculate the molar ratio of its elements? Can energy dispersive spectroscopy (EDS) show the presence of each elements involving bonding in nanostructures like nanowires and nanotubes?
Do you know any other way to calculate the molar ratio of elements in these type of nanostructures?
Dear Ramin,
There are two techniques mainly to know about the molar ratios of elements in a structure. One is XPS and other is EDS. From XPS, we only get the information about a few nanometers deep down some structure so you can't rely on it. But yes, EDS, for sure, gives you the desired information. You will get the elemental rations both in atomic % and weight %. In your case, as you have synthesized nanowires, I would suggest you use EDX (compositional and mapping analyses) in terms of TEM rather that SEM. It will give you accurate results. I hope it would work for you!
Good luck and remember me in good wishes if this answer helps you out!
EDS provides crude elemental information regardless of the oxidation state or bonding characteristics. in order to get additional information XPS is useful.
Dear Ramin,
There are two techniques mainly to know about the molar ratios of elements in a structure. One is XPS and other is EDS. From XPS, we only get the information about a few nanometers deep down some structure so you can't rely on it. But yes, EDS, for sure, gives you the desired information. You will get the elemental rations both in atomic % and weight %. In your case, as you have synthesized nanowires, I would suggest you use EDX (compositional and mapping analyses) in terms of TEM rather that SEM. It will give you accurate results. I hope it would work for you!
Good luck and remember me in good wishes if this answer helps you out!
Thanks Dr.Moazami and Dr.Ehsan. I appreciate your answers.
Dear Muhammad, I wish it will be so!
The two techniques suggested by the colleagues above are both appropriate, but neither will give very accurate values. XPS is highly surface selective and will only reflect the composition at the surface, which may be different, even for nanoparticles or wires, and EDX, as mentioned by Hamid Reza Moazami, will only give a rather crude estimate. I would suggest to chemically isolate the material, i.e. wash away any impurities apart from the solvent, and then carry out proper elemental analysis, for example by ICP-AES or -AAS or -MS depending on the types of elements you expect to be present and the techniques available. Suitable digestion may be needed before, although many nanomaterials can go straight into the plasma as suspensions. This will give you very accurate elemental compositions but of course no information on the spatial distribution of these elements within the nanostructure.
EDS is good to take a look at the homogeneity of the materials at the nanoscale, but like with any microscopy based technique it is hard to justify its statistical significance. Also, as far as I understand EDS is not too good for light elements, I believe S is OK, otherwise EELS should work. I agree with Mathias that ICP is a more appropriate technique for quantification as your sample size is orders of magnitude larger. Digestion of your samples should be pretty easy with HNO3. Another option could be XRF.
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