Raman spectroscopy of ethane (C2H6) to 120 GPa at 300 K

We have conducted a Raman study of solid ethane (C2H6) at pressures up to 120 GPa at 300 K. We observe changes within the ν3 and ν11 Raman‐active vibrational modes providing evidence for several previously unobserved phase transitions at room temperature. These are located from 16 to 20 GPa, ~35 GPa, and ~60 GPa. We also could no longer measure the ν3 and ν11 modes from 75 GPa onward. We did not, however, observe any signs of the ethane molecule undergoing decomposition, up to the highest pressures measured. We also recorded spectra of the (2ν8, 2ν11), ν1, and ν10 modes but observed more limited changes in the behaviour of these modes. Ethane is a unique and important molecule; it is the simplest molecule containing an sp2 CC bond and occurs naturally in the outer planets and in natural gas. However, very little is known about its behaviour at extreme pressure and temperature. Here, we study ethane with Raman spectroscopy in the diamond anvil cell to 120 GPa and find evidence for several structural phase transitions.