For a particular diatomic molecule, the spacing between vibrational energy levels is 0.12 eV. If such a molecule is in the 4th vibrational excited state, which of the following photons can be absorbed to excite the molecule to the next higher vibrational state?
1) 0.12 eV
2) 0.24 eV
3) 0.36 eV
4) 0.48 eV