Differential brightness temperature of hot halos (T_b ≈ 2280 K) in the base rotational lines H₂, HD and HeH⁺ (from top to down) with and without of the first light: solid dark line is without the first light; solid red and blue lines with background are the first light that reionize the medium at z = 6 and z = 8, accordingly; dotted and dashed blue lines with the first light with an energy density that is 10³ and 10⁶ times higher than the background one (z_rei = 8). In the left column, the first light is Ia, in the right one – Ib.