Detection and application of carbon recombination lines in millimeter range

We carried out millimeter-range observations of carbon radiolines from Photo-Dissociation Regions (PDRs). Comparison with observations of these objects in infrared fine structure lines of CII and OI allows one to determine the physical conditions in the PDRs (density, temperature, and thickness of the PDR layer) that were done for several regions connected to HII regions. It is shown that recombination radiolines also allow the kinematics of the complexes including HII regions and PDRs to be traced.