[en] The authors present results of simulations of experiments in which polystyrene (CH) shells filled with argon gas were imploded with the 24-beam UV (351-nm) OMEGA laser. The one-dimensional hydrodynamic code LILAC, which includes an average-ion model, is used to compute the conditions in the core. The temperature and density profiles are then entered into a postprocessor that calculates the atomic physics and radiative transport in terms of a multi-species detailed-configuration atomic model. The species populations and the spectra predicted by the postprocessor indicate that density-broadened argon lines are emitted before shock reflection from the target center. During the shock return to the shell, the simulations indicate that emission from the dense hot center part of the core (n_e > 10²⁵ cm^-3) will be absorbed by the species present in the cooler and less dense outer part of the core (n_e < 5 x 10²⁴ cm^-3). Simulation results are compared with experimental measurements