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Posted: **Fri May 06, 2022 6:34 am**

: 2 3 A The Einstein A Coefficient Of The 3p 3p 2 38 S1 2 Transition In Sodium Is 6 14 X 107 S A Gas Of Sodium At 1 (46.91 KiB) Viewed 23 times

2 3 (a) The Einstein A coefficient of the 3p² 3P₁/2 →38² ³S1/2 transition in sodium is 6.14 x 107 s¹. A gas of sodium atoms is excited to the 3p2 ³P1/2 level at time t = 0. What fraction of the atoms are still in the upper level after 20 ns ? [5 marks]