Complex sentence: In a certain frequency range, if the transitions of the absorbing centers are relatively sparse, the absorption spectrum in this region would be of a series of lines, each corresponding to a single transition or either completely or partially resolved from neighboring lines.
Split into simpler sentences: In a certain frequency range, if the transitions of the absorbing centers are relatively sparse, the absorption spectrum in this region would be of a series of lines. Each line would correspond to a single transition and be either completely or partially resolved from neighboring lines.