Given,
\(C=\cfrac { \sqrt [ 3 ]{ n_{ 2 } } -\sqrt [ 3 ]{ n_{ 1 } } }{ \sqrt [ 3 ]{ n_{ 1 }n_{ 2 } } } -\cfrac { n_{ 2 }^{ 2 }-n_{ 1 }^{ 2 } }{ (n_{ 1 }n_{ 2 })^{ 2 } }\)
when \(n_2\lt n_1\), for absorption lines, \(n_1\leftrightarrow n_2\),
\(D=\cfrac { n_{ 2 }^{ 2 }-n_{ 1 }^{ 2 } }{ (n_{ 1 }n_{ 2 })^{ 2 } }-\cfrac { \sqrt [ 3 ]{ n_{ 2 } } -\sqrt [ 3 ]{ n_{ 1 } } }{ \sqrt [ 3 ]{ n_{ 1 }n_{ 2 } } } =-C\)
And so we can expect the spectra line \(n_{1\rightarrow 2}\) to cancel the reverse spectra line \(n_{2\rightarrow 1}\).
For the sake of it....
