Mg ii k line profiles of the normally emergent radiation from the slab with D = 1000 km and T = 8000 K. The two sets of curves correspond to values of the gas pressure p = 0.01 and 0.1 dyne cm^-2. For each pressure, three curves show an increasing line broadening for the three values of the microturbulent velocity: 0 km s^-1 (black), 3 km s^-1 (dark gray), and 8 km s^-1 (light gray).