Question

3b

Two of the adjacent absorption lines in the pure rotational spectrum of 23Na81Br occur at 3.623 and 3.92 cm-1 . Assuming 23Na81Br behaves as a rigid rotor:

i) Calculate the moment of inertia for this molecule.

ii) Calculate the bond length of 23Na81Br.

iii) Determine the most intense transition in the rotational spectrum of 23Na81Br if the measurement is carried out at 25oC.

c

The rigid rotor model assumes that the molecular bond does not stretch during rotation. Describe with the aid of an energy level diagrams how taking into account centrifugal distortion affects the rotational energy levels of a diatomic molecule. Include any relevant energy equations in your explanation and describe why the rotational constant, B should always be estimated from the low energy end of the rotational spectrum.

Answer 1