I am dealing with the synthesis of gold nanoparticles. when I add reducing agent I got two SPR bands one at 480 nm and other at 720nm. Is it possible that transverse SPR band for nano gold can appear at 480 nm?
Tayyaba,yes it is possible , SPR band of nanoparticles depends on method of preparation,nature of solvent in which NP's are suspended ,nature of capping agent,and others species around nanoparticles in the system,even it depends on the size of particles greater size give more red shift while smaller at blue shift,for more satisfaction repeat your synthesis with different conditions taking above factors ,you will find various bands for the same metal nanoparticles, even the solution colour of the same nanoparticles, will be little bit different,but my suggestion is to pick the way which gives you the more blue shift (particles in nano range).in my opinion 480 nm is a good idea but 780 nm is indication of larger particles (precipitation,agglomeration and aggregation).
Regard
Muhammad imran khattak
thanks a lot but please can you justify it through literature in which SPR band for nano gold is at 480nm?
HI Tayyaba
It might be due to your environment although I have never seen less than 500 nm for any gold structure. Make sure you have purified your NPs and perform the measurement in water.
720 nm might be due to some anistropic structure. You should take TEM to see the exact shape.
Best Regards,
Mohammad
In my knowledge, may be 480 nm indicate Quantum dot
and 720 nm indicate nanorod.
In my opinion, you need to use TEM AuNPs starting from SPR 500.Usually, 7 nm has SPR band at 520 in the UV, so any band less than 500 it will be your ligands or contamination.I prepared Gold nanoparticles at different size including 6,7,8,11.
All the best.
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