The plot shows the matrix-isolation FTIR spectrum of methane (CH4 and CD4), with analye:matrix ratios of 1:1000 and 1:2000. Methane shows hindered rotation in the matrix, which becomes better resolved at much higher dillutions, as discussed in Dinu 2020
. CH4:Argon (1:1000) CSV-File CH4:Neon (1:1000) CSV-File CD4:Argon (1:1000) CSV-File CD4:Neon (1:2000) CSV-File