A hypothetical diatomic molecule of oxygen (mass = 2656 x 10-26kg) and hydrogen (mass = 1.67 x 10^-27 kg) emits a photon of wavelength 2.39µm when it makes a transition from one vibrational state to the next lower state. If we model this molecule as two point masses at opposite ends of a mass less spring, 

(a) What is the force constant of this spring, and 

(b) How many vibrations per second is the molecule making?