Physics

Problem

An atom exhibits two successive emission lines as it returns to the ground state: a photon of wavelength

400\,\text{nm}

followed immediately by a photon of wavelength

652\,\text{nm}

. The atom’s excited energies above the ground state are listed below:

E_1 = 1.90\,\text{eV}

E_2 = 3.10\,\text{eV}

E_3 = 5.00\,\text{eV}

E_4 = 5.80\,\text{eV}

. (Use

E\,(\text{eV}) = 1240/\lambda\,(\text{nm})

.) From which single excited level did the electron most likely start before emitting the two photons in sequence? a)

E_4

E_2

E_3

E_1