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Visible Raman Scattering: 532nm 100mW laser through Muriatic Acid

Shown here is the effect of shining a green laser beam through muriatic acid (HCl and water). The scattered red 650nm glow is a result of O-H stretching seen as a 3450cm-1 energy shift from the incident 532nm laser.

 

The chlorine anion increases the polarizability of the water which intensifies the 3450cm-1 shift.

 

 

Photographed through magenta laser protection goggles.

 

"The differences in the hydrogen-bonded stretching of the IR and Raman spectra of the acid solutions can be attributed to the different selection rules. For a mode to be Raman active, there must be a change in polarizability with the vibration. As acids with increasingly polarizable anions (Cl - < Br - < I - ) are added, the water molecules solvating these anions exhibit increased polarizability; thus, since Raman intensities arise from this condition, this effect is observed in the Raman spectra."

See:

www.researchgate.net/figure/231641619_fig2_Figure-3-Isotr...

 

This effect was also seen in a saturated saline solution although it wasn't nearly as bright.

See:

www.researchgate.net/publication/45707038_Experimental_St...

 

 

Lecture on vibrational spectroscopy:

131.104.156.23/lectures/CHEM_207%20copy/vibrational_spect...

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Uploaded on March 11, 2017
Taken on March 11, 2017