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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: _Espard_ on March 01, 2015, 06:51:30 PM

Title: Unexplained blue shift in UV-Vis experiment
Post by: _Espard_ on March 01, 2015, 06:51:30 PM

I am running a UV-Vis spectroscopy experiment and witnessed slight blue shift in my spectra that I cannot explain.

The experiment consists of a mixture of a metal salt and an organic compound in water. The s#*$ is only witnessed when the two are mixed together, as individual UV-Vis spectra show the correct (unshifted) peaks.

My assumption was that blue shifts are typically seen due to the effects of solvents and do not typically arise for same-solvent (i.e. water) experiments. My first thought would be some sort of charge-transfer complex - but doesn't this typically lead to lower-energy red shifts?

Title: Re: Unexplained blue shift in UV-Vis experiment
Post by: Corribus on March 02, 2015, 10:26:37 AM

More details about what you're doing are needed. Also, seeing the actual spectra would be helpful, because what you call "slight" may be different from what I call "slight". Spectral shifts can be due to lots of things.