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We analyse the thermal emission and resonant scattering of CMB radiation fromthe dark ages halos in the rotational lines of the helium hydride ion(HeH$^{+}$), one of the first chemical compounds in the Universe. Evaluatingthe optical depth, thermal and resonant brightness temperatures and spectralfluxes of dark ages halos is based on computing the cross-sections and ratecoefficients of excitation/de-excitation of the lowest five rotational statesof HeH$^{+}$ by inelastic collisions with atomic hydrogen. It was shown that inthe Dark Ages the collisional excitation/de-excitation by atoms of neutralhydrogen and electrons are competitive, whereas in the denser regions, e.g., inthe halos, the contribution of collisions with atomic hydrogen is dominant. Wedemonstrate the peak-like time-dependence of halo luminosities in HeH$^{+}$lines.

Thermal and Resonant Emission of Dark Ages Halos in the Rotational Lines of HeH$^{+}$