21. Two states were proposed for 1, 4-didehydrobenzene : singlet and triplet, with the singlet state lower in energy. 22. The singlet states of oxygen are 158 and 95 kilojoules per mole higher in energy than the triplet ground state of oxygen. 23. Statistically, there is a 25 % probability of forming a singlet state and 75 % probability of forming a triplet state. 24. The mechanism of singlet state deactivation is theorized to occur through halogen-lone pair complexation of empty 1Fl P-orbitals. 25. NMR measurements of the resonance frequency on YBCO indicated that electrons in the copper oxide superconductors are paired in spin-singlet states . 26. The decay from the excited singlet state ( S1 ) to the ground state ( S0 ) is via fluorescence ( S1 ? 27. S2 ); whereas the Q band is a result of a weak transition to the first excited singlet state ( S0 ? 28. In another meaning a closed shell configuration corresponds to state with all molecular orbitals doubly occupied or empty ( a singlet state ). 29. Photochemical or thermal activation can bring it into the singlet state , which makes it kinetically as well as thermodynamically a strong oxidant. 30. The lower lying singlet states of He 2 are A 1 ? u, B 1 ? g and C 1 ? g.
