Can Raman spectroscopy identify every substance?

[David lopez]

Can raman spectroscopy identify any substance or are there certain
Substances raman spectroscopy cannot identify?

 

[Dr Transport]

in theory, yes. All point groups have active Raman modes, but the magnitude may not be large enough to measure.

 

[David lopez]

What substances have raman modes
Too small to measure?

 

[David lopez]

If somebody built a raman spectroscopy, is there any reason 5 milliwatts would be inadequate for this
Application?

 

[pellis]

in theory, yes. All point groups have active Raman modes, but the magnitude may not be large enough to measure.

When you write "In theory, yes", will the OP have realized that you're answer applies only to bound substances with rotational and vibrational states: mainly molecules and solids (point groups)?

Obtaining raman spectra in liquid state studies can be difficult: https://www.researchgate.net/post/How_to_prepare_liquid_sample_for_Raman_spectrometer_to_get_good_spectrum

But unless they display very-low-energy electronic transitions, I would expect monatomic gases such as noble gases to be completely transparent to raman spectroscopy (except when adsorbed onto a surface, in which case such spectra have been observed, e.g. https://www.semanticscholar.org/pap...hita/ce681015459750bb4dfc4882d3d125b2b5869046).

Regards - P