The mm-wave reflection of (TMTSF)(2)PF6, measured at a pressure of 10 kbar
in the frequency range 40 to 285 GHz (1.3 to 9.5 cm(-1)), for B up to 16.5T
and T down to 600mK, shows several transitions to FISDW states, coinciding
with features in magnetotransport. One new resonance with a heavy-mass of
1.5 m(e) (with Q approximate to 6) exists in the metallic state only, at B
< 7.3 T, and can be associated with CR on the open orbit. A lighter one at
0.95 m(e) (with Q approximate to 25) persisting both in the metallic and in
the FISDW states, may be spin-resonance.