I am a physical chemist and, therefore, am familiar with UV/Visible spectroscopy. The spectrum in question, which is a kinetics study of Ag nanoparticle growth, is clearly not maxed out but something causes the spectrum to go flat (or nearly flat) after about 500 nm. If it was complete scattering, I would expect it to go to zero percent transmission (or an absorbance of 3 on this machine) but that is not what we see. My guess is almost complete diffuse scattering due to nanoparticle size and concentration. However, I thought I would crowd source and see if that is reasonable.
Cherice Evans You're right to suspect diffuse scattering due to nanoparticle size and concentration, especially since the Ag nanoparticle growth likely results in particle aggregation or size increase beyond the Rayleigh scattering regime. The spectrum flattens due to strong Mie scattering from growing or aggregated Ag nanoparticles, which diffusely scatters light and reduces distinct plasmonic absorbance features.
I think the flat baseline beyond ∼500 nm reflects Mie‐type diffuse scattering from your growing Ag nanoparticles, not true absorption. Only part of the scattered light misses the detector, so you see a low, flat absorbance instead of ramping to 3 AU.
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