  We present medium resolution optical and NIR spectral data for components of
the newly discovered WISE J104915.57-531906.1AB (Luhman 16AB) brown dwarf
binary. The optical spectra reveal strong 6708 A Li I absorption in both Luhman
16A (8.0+/-0.4 A) and Luhman 16B (3.8+/-0.4 A). Interestingly, this is the
first detection of Li I absorption in a T dwarf. Combined with the lack of
surface gravity features, the Li I detection constrains the system age to 0.1 -
3 Gyr. In the NIR data, we find strong KI absorption at 1.168, 1.177, 1.243,
and 1.254 {\mu}m in both components. Compared to the strength of KI line
absorption in equivalent spectral subtype brown dwarfs, Luhman 16A is weaker
while Luhman 16B is stronger. Analyzing the spectral region around each doublet
in distance scaled flux units and comparing the two sources, we confirm the J
band flux reversal and find that Luhman 16B has a brighter continuum in the
1.17 {\mu}m and 1.25 {\mu}m regions than Luhman 16A. Converting flux units to a
brightness temperature we interpret this to mean that the secondary is ~ 50 K
warmer than the primary in regions dominated by condensate grain scattering.
One plausible explanation for this difference is that Luhman 16B has thinner
clouds or patchy holes in its atmosphere allowing us to see to deeper, hotter
regions. We also detect comparably strong FeH in the 0.9896 {\mu}m Wing-Ford
band for both components. Traditionally, a signpost of changing atmosphere
conditions from late-type L to early T dwarfs, the persistence and similarity
of FeH at 0.9896 {\mu}m in both Luhman 16A and Luhman 16B is an indication of
homogenous atmosphere conditions. We calculate bolometric luminosities from
observed data supplemented with best fit models for longer wavelengths and find
the components are consistent within 1{\sigma} with resultant Teffs of
1310+/-30 K and 1280+/-75 K for Luhman 16AB respectively.
