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I'm wondering if someone can give me a physically motivated reason for why chiral molecules interact with left and right circularly polarized light (LCP) (RCP) differently. Particularly, a quantum mechanical view of what's happening here.

I understand why it is that a molecule has to be chiral in order for it to manifest circular dichroism (my use of terminology may not be perfect here so I apologize). That is, both the electric and magnetic dipole operators must be non-zero and there's an argument here on the basis of point groups.

Nothing about that, however, is particularly illuminating when it comes to understanding why I should expect a molecule to interact differently with LCP and RCP light.

I don't know what else I can even say. A good answer would address the different behavior of both the light and the molecule in these different situations, as I imagine that's a necessary piece to the puzzle.

Also, if one has some references (a review or textbook chapter etc.) that would be appreciated.

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    $\begingroup$ see chemistry.stackexchange.com/questions/1012/… $\endgroup$ – Mithoron Nov 30 '16 at 16:37
  • $\begingroup$ also chemistry.stackexchange.com/questions/6271/… $\endgroup$ – Mithoron Nov 30 '16 at 16:38
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    $\begingroup$ Chiral molecules interact differently with chiral light, just like a screw (chiral) interacts differently if you twist it clockwise or counterclockwise with a screwdriver. $\endgroup$ – jjgoings Dec 1 '16 at 18:58
  • $\begingroup$ Hmm... Perhaps I need to do some reading before I can really give words to the thing that's bothering me cause it might just be based on simple misunderstandings. @jjgoings do you know of any references that discuss this on a simple level I could look into? $\endgroup$ – jheindel Dec 2 '16 at 2:59
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    $\begingroup$ @jheindel Check out "Molecular light scattering and optical activity"(2004) by Lawrence Barron. Mechanistically, it will help if you consider chiral molecules like the helicenes (en.wikipedia.org/wiki/Helicene) rather than a 'typical' chiral molecule with a stereocenter. Simplistically, think about how it will be easier to polarize the electron density if the circular polarization matches the contour of the helicene rather than polarizing with the opposite 'handedness'. If, say, LCP light polarizes the molecule more strongly than RCP, there will be a difference in absorption intensity. $\endgroup$ – jjgoings Dec 2 '16 at 21:42

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