Hi! I was synthesizing some gold nanorods. What's interesting is, that in one of my trials a negative value in the UV-VIS (around 630nm) was obtained. How is that possible? Also, it was done by common seed-mediated methods using CTAB. Also, I know this is not the spectra of a gold nanorod, I believe it can be a bone shape. I kind of try to do a few things different and this is what I got...
Dear Alberto Rodríguez,
It is likely the artefact caused rather the real signal when you took UV VIS measurements. Did you do the baseline without any sample in the optical paths for both reference beam and sample beam? And also the aperatures are crucial too for the measurements using a UV-VIS spectrophotometer.
Hope it helps
Alberto Rodríguez Inadequate background subtraction is the only way that this could have occurred. Wavelength is also spelled incorrectly on the horizontal axis.
This is not true signal .. I agree with previous answers as it is mostly related to background and baseline ..
Alberto Rodríguez Now, when the gold sol is measured the color (purple here?) means that the power of the light is attenuated. This reduced power will not be present in the background measurement if you're using pure water (for example). This means that the background may be over-subtracted as the light intensity was higher in this situation. Are you using a dual-beam system?
Your starting point (around 850 nm) is also negative and that you are hiding. Go for scanning baseline before scanning the sample.
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