An oxygen atom at a particular site within a DNA molecule can be made to execute simple harmonic motion when illuminated by infrared light. The oxygen atom is bound with a speing-like chemical bond to a phosphorous atom is bound which is rigidly attached to the DNA backbone. The oscillation of the oxygen atom occurs with frequency ƒ=3.7 x 1013Hz. If the oxygen atom at this site is chemically replaced with a sulphur atom, the spring constant of the bond is unchanged (sulphur is just below oxygen in the Period Table). Predict the frequency for a DNA molecule after the sulphur substition.