Measuring in-situ light scattering, UV-spectra or refractive index may work.

Ummm.... Different factors might play an important role in your case Manjeet.

For the time being, I would suggest you design a few more experiments. For example, you should perform a series of experiments with different ratios of EG. You can try 0%, 20%, 40%, 60%, 80% and 100% EG to investigate the more detailed role being played by EG. Now once you find the optimized condition, say it is 40% EG and 60% water, then you should perform one more series of experiments while changing the time of your reaction. I believe that once you finish with these experiments, you would be much more clear with the growth mechanism.

Good luck!

You could also try taking a drop of the reaction mixture at different time-points and preparing TEM samples. If size is an issue, perhaps dilute a few drops of the reaction mixture in water and try Nanoparticle Tracking Analysis. It will also give you an estimate of the nanowire concentration at different time-points.

http://onlinelibrary.wiley.com/doi/10.1002/chem.201000341/full This may give some helpful inside (the paper deals with EG synthesis of silver nanocubes, including characterization during synthesis).

Good luck!

Thank you Teodora Miclaus , Muhammad Fahad Ehsan and Titus Sobisch for replying.

Teodora i dont know much about nanoparticle tracking analysis.would you please explain. i wanted to see the evolution of morphology so even if i do UV or measure Refractive index that would not confirm what i want. also if i take the reaction mixtures at different times and do FESEM or TEM how do i quench the reaction at that particlur time.

Mr Ehsan i am actually doing the experiments and trying to find the mechanism of growth by varying the reaction parameters. thank you very much

If you are using the polyol method (so ethylene glycol as both solvent and reducing agent), the reaction is quenched simply by decreasing the temperature (EG acts as a reducing agent only at high temperatures, as far as I know): a drop of reaction mixture into a few drops of cold water, after which this mixture could be used to prepare TEM samples. I think this should do the trick. As far as NTA goes, it works on the same principles as DLS, but it analyzes the system particle by particle, not as a bulk, therefore providing higher resolution in terms of size distribution. It also gives some info about the particle concentration (as it counts the particles it tracks), so you can use that to back-calculate and have an estimate of the concentration in your reaction mixture at specific times. It will, however, not give you information about morphology as, similar to DLS, it does approximate everything to a spherical particle moving in the liquid.

UV-VIs should confirm changes in morphology, as different shaped particles of the same material have different localized surface plasmon resonances. I use this to track synthesis of silver nanocubes.

I hope this helps.