Peak shifts

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  • #5063

    • Sophomore Member
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    Does anyone know why the peaks of silver nanoparticles would differ from UV-Vis? When I run the colloid on UV-Vis the peak reads at 426 nm, but when I do hyperspectral the peaks range from 475-600 nm (blue to red).


    • Expert
    • ★★★★★


    Thank you for the inquiry. Let’s see if we can help clarify why you may be seeing these differences.

    CytoViva’s system measures reflectance spectra using Vis Nir excitation. Normally the UV-Vis system measures absorption using UV laser. In our case, Vis Nir reflectance will always have a red shifted spectrum vs UV-Vis absorption spectrum.

    Also, the UV-Vis spectrograph is likely only giving you a single mean absorption spectra of all of the measured particles. CytoViva’s hyperspectral provides individual spectrum from single NPs as well as aggregates, which aggregates always red-shift in plasmonic NPs such as AgNPs.

    In the case of the different measurements, both measurements are accurate. They are simply two different measurement techniques measuring two different things in the same sample.

    Metaphorically, it is like measuring an item using both kilo and pound scales. Both measure the weight of the item correctly, but they are doing so using different methods.

    Hope this helps!

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