I am a first year graduate student in physics and am becoming familiarized with Raman spectroscopy to study structure of materials based off of their vibrational states. In some personal study outside of this, I came across the idea of inelastic electron tunneling spectroscopy (IETS) and was wondering if anyone knew of when/why one is used over the other. I did some research and it seems Raman is a much more widely used technique, but IETS seems to offer more information with little extra work. Since it doesn't work by shining laser light on a material and measuring a response (but rather inelastic tunneling, obviously by the name), IETS can give information on optically forbidden transitions unlike Raman. This is more a question out of curiosity more so than something super technical, but does anyone have experience working with IETS? I'm interested to hear any comparisons between IETS and Raman. Could anyone contrive a situation where IETS may be more practical or "useful" than Raman? Thanks in advanced!