The molecular spectroscopic methods of CBR-temperature measurement in epochs with large redshifts

There is the possibility to measure the background radiation temperature in earlier cosmological epochs. If the background radiation temperature changes linearly with change of redshift, it can coincide with the excitation temperature of molecules rotational levels. The present paper deals with the situation arising when the background radiation field dominates in the population of CH-rotational level . At Z>2 the hyperfine structure lines of this level shift to the millimeter radio-region and can be observed by radio-astronomical methods. They can be the absorption lines observed in QSO absorption spectra.