Fitted curve (red solid line) of the measured DR spectrum below 1.2 eV. The blue solid line indicates the fitted RR background and the blue dashed lines depict the line shape of each single peak. The fitted parallel and perpendicular electron temperatures are k_BT_∥ = 0.56(0.05) meV and k_BT_⊥ = 23(1) meV, respectively. Δα denotes the recombination rate enhancement at very low energies (below 100 meV) which is the artifact of the merged-beam method (Gwinner et al. 2000).