Split from Spectroscopy Discussion Thread

[photon79]

A laser in visible is used in Raman spectroscopy and the resultant spectrum is in IR and Microwave region(which means molecular vibrations and rotations are excited), what type of interaction is this that induces these levels? ( I cannot think more than..."To be Raman active molecules should posses anisotropic polarizability".)my question is how vibration or rotation can be excited during the scattering? (As the source used is visible, I think some basic understanding is missing from my side)

 

[Plastic Photon]

THis is all very foreign to me and several semesters away, but...

reading through Pauling's General Chemistry, there is a sketch of a simple spectrocope.

It is simply a network of a telescope positioned towards a prism at an angle respective to a collimator. The objective is to use a light source to shine through the collimator, refract it into the prism to allow the light to be seen by the observer looking through the telescope. It also states that a ruled grating can be substituted for diffraction.

I have a telescope but no prism and collimator. But if I were to buy a collimator, prism, and a ruled grating, what kind of results what I get back using this system, what could I possibly achieve?

 

[Moonbear]

Just a note that I've moved these posts from the Spectroscopy Discussion Thread. The original post in that thread seemed to get eaten by the PF Gremlins, and as a result, the discussion drifted off topic. These are questions worthy of their own thread.

 

[Gokul43201]

A laser in visible is used in Raman spectroscopy and the resultant spectrum is in IR and Microwave region...

Note : This question has been answered in other places, like here. Photon79 is aware of this.

Now its much clear to me.
My question was "How can we absrove rotations and/or vibrations in Raman spectra where we use visible source?"
Here what happens is molecule is excited to a virtual state (as Gokul said)say 20,000 Cm-1 which is in visible and scattered at lower vibrational say, 19,000 Cm-1 which is also in visible , what we measure in Raman spectra is difference in these levels 1,000 Cm-1 which is in IR. This is the basis and we get spectral lines in visible but we take the difference which will be in Microwave or IR.

More info and any currections are appriciated.

So [Moonbear], you could probably delete the OP here and leave the thread with plastic photon's question. <and then delete this post too>