The possibility of detecting cosmological signals from the postrecombi
nation universe is one of the main aims of modern cosmology. In a prev
ious paper we emphasized the role that elastic resonant scattering thr
ough WH molecules can have in dumping primary cosmic background radiat
ion (CBR) anisotropies and raising secondary signals. Here we extend o
ur analysis to all the evolutionary stages of a primordial cloud, star
ting with the linear phase, through the turnaround, and to the nonline
ar collapse. We have done calculations for protoclouds in a cold dark
matter (CDM) scenario and, more generally, for a set of clouds with va
rious masses and various turnaround redshifts, in this case without re
ferring to any particular structure formation scenario. We found that
the first phase of collapse, for t/t(free-fall) = 0.05-0.2 is the best
one for simultaneous detection of the first two LiH rotational lines.
The observational frequency falls between 30 and 250 GHz, and the lin
e width Delta nu/nu is between 10(-5) and 10(-4). As far as we know, t
his is the most favorable process to detect primordial clouds before t
hey begin star formation processes.