The wavelength in air associated with a photon of energy E is (c is the speed of light in air and h is the Planck's constant)

Energy of a photon is given by $\mathrm{E} = \mathrm{h}\nu$.  

Now, we know frequency and wavelength are related by $v=\frac{\mathrm{c}}{\mathrm{\lambda }}$.  where c is the speed of the light. Hence,

$$\begin{gathered} \mathrm{E}=\frac{\mathrm{hc}}{\mathrm{\lambda }} \\ \Rightarrow \mathrm{\lambda }=\frac{\mathrm{hc}}{\mathrm{E}} \end{gathered}$$