The energy carried away in a one-quantum change is given by
[tex]E=hf[/tex]
where
h is the Planck constant
f is the frequency of vibration
For the system in this problem, the frequency of vibration is [tex]f=0.56 Hz[/tex], therefore the energy of one quantum of vibration is
[tex]E=hf=(6.6 \cdot 10^{-34} Js)(0.56 Hz)=3.7 \cdot 10^{-34} J[/tex]