(4.7) Mercury has a relative atomic mass of 200.6 and an atomic radius of 0.17 nm. The transi- tion at 546.1 nm has an Einstein A coefficient of 4.9 x 10' s . Calculate the natural, Doppler, and collisional linewidths in frequency units (Hz) for this transition in: (a) a low-pressure lamp operating at 250? C with a pressure of 10 atmospheres, (b) a high-pressure lamp operating at 500 C with a pressure of 1 atmosphere