Optical data on volatile ices

N2 Grundy, Schmitt, and Quirico 1993, Icarus 105, 254-258.
H2O Grundy and Schmitt 1998, J. Geophys. Res. 103, 25,809-25,822.
CH4 Grundy, Schmitt, and Quirico 2002, Icarus 155, 486-496.
CH3D Grundy et al. 2011, Icarus 212, 941-949.
CH4+N2 Protopapa et al. 2015, Icarus 253, 179-188
CH3OH Cook et al. 2019, Icarus 331, 148-169

Lots more are on the way...