Potential energy curves in excited electronic states

1 Potential energy curves in excited electronic states 

In addition to these laboratory-based experiments it is interesting to note that the Swan bands of C2 are important in astrophysics. They have been observed in the emission spectra of comets and also in the absorption spectra of stellar atmospheres, including that of the sun, in which the interior of the star acts as the continuum source. 

Just as in the ground electronic state a molecule may vibrate and rotate in excited electronic states. The total term value S for a molecule with an electronic term value T, 

The vibrational term values for any electronic state, ground or excited, can be expressed, as in Equation (6.16), by 

Transition Names associated Special region/nm Source of spectrum 

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