11. As these metals go superconducting, electrons with oppositely directed spins couple to form singlet states . 12. The ground electronic state of carbon monoxide is a singlet state since there are no unpaired electrons. 13. The radiative decay from an excited triplet state back to a singlet state is known as phosphorescence. 14. Per the radical pair mechanism photopigments absorb a photon, which elevates it to the singlet state . 15. Let \ phi be the spin singlet state for a pair of electrons discussed in the EPR paradox. 16. The molecule is excited with near infrared radiation to the singlet state ( with no unpaired electrons ). 17. Almost all molecules encountered in daily life exist in a singlet state , but molecular oxygen is an exception. 18. The result is a slow process of radiative transition back to the singlet state , sometimes lasting minutes or hours. 19. Initially, the absorption of a photon causes an electron to be excited into a singlet state of the Q band. 20. The Soret band arises from a strong electronic transition from the ground state to the second excited singlet state ( S0 ?
