  We investigated the absence of certain bright peaks in Autler-Townes laser
excitation spectra of alkali metal atoms. Our research revealed that these dips
in the spectra are caused by a specific architecture of adiabatic (or
``laser-dressed'') states in hyperfine (HF) components. The dressed states'
analysis pinpointed several cases where constructive and destructive
interference between HF excitation pathways in a two-photon excitation scheme
limits the available two-photon transitions. This results in a reduction of the
conventional two-photon selection rule for the total angular momentum $F$, from
$\Delta F= 0,\pm 1$ to $\Delta F\equiv 0$. Our discovery presents practical
methods for selectively controlling the populations of unresolvable HF
$F$-components of $ns_{1/2}$ Rydberg states in alkali metal atoms. Using
numerical simulations with sodium and rubidium atoms, we demonstrate that by
blocking the effects of HF interaction with a specially tuned auxiliary control
laser field, the deviations from the ideal selectivity of the HF components
population can be lower than $0.01\%$ for Na and $0.001\%$ for Rb atoms.
