The longest wavelenght doublet absorption transition is observed at 589 and 589.6 nm. Energy difference between two excited states is

Explanation

`lambda_(1)=589 nm=589xx10^(-9)m`
`:. V_(1)=c/lambda_(1)=(3.0xx10^(8)ms^(-1))/(589xx10^(-9)m)=5.088xx10^(14) s^(-1)`
`lambda_(2)=589.6 nm =589.6xx10^(-9) m`
`:.v_(2)=c/lambda_(2)=(3.0xx10^(8)m s^(-1))/(589.6xx10^(-19)m)`
`=5.088xx10^(14) s^(-1)`
`DeltaE=E_(2)-E_(1)`
`=h(v_(2)-v_(1))`
`=(6.626xx10^(-34)J s)(5.093-5.088)xx10^(14) s^(-1)`
`3.31xx10^(-22)J`