code: def em_rates_from_E_DA(em_rate_tot, E_values):
      
      E_values = np.asarray(E_values)
      em_rates_a = E_values * em_rate_tot
      em_rates_d = em_rate_tot - em_rates_a
      return em_rates_d, em_rates_a
docs: Donor and Acceptor emission rates from total emission rate and E (FRET).