Browsing by Author "Phillips, David"

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    Photochemistry of 1,3-DichIoro-tetrafluoroacetone: Part 2.—The Triplet State
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (2), 1972) Hackett, Peter A.; Phillips, David
    Quantum yields of S1→ T1 intersystem crossing in 1,3-dichloro-tetrafluoroacetone have been measured using the technique of biacetyl sensitization. The vibrationally-relaxed singlet state of the molecule intersystem crosses to a dissociative triplet with quantum yield 0.92. Vibrationally-excited singlet-state molecules do not intersystem cross, but may dissociate in two ways.
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    Photochemistry of 1,3-Dichloro-tetrafluoroacetone: Part 1.—The Singlet State
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (2), 1972) Hackett, Peter A.; Phillips, David
    The variation of the fluorescence quantum yield of 1,3-dichloro-tctrafluoroacetone with pressure of ketone and added gases is reported for several different exciting wavelengths. Fluorescence decay times were also measured. A mechanism is proposed to account for the results, and rate constants lor vibrational relaxation, fluorescence and non-radiativc decay processes tabulated. These are compared with similar results for other fluorinated ketones.
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    Photochemistry of 1,3-Dichloro-tetrafluoroacetone: Part 3.—Quenching of the Excited States
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (2), 1972) Hackett, Peter A.; Phillips, David
    The quenching of the excited singlet and triplet states of 1,3-dichloro-tctrafluoroacctone by various molecules is reported. Correlation of results with decomposition data indicate that for 310 nm excitation, some 25-30 % of the decomposition products arise from the singlet state, the remainder from the triplet state. The various mechanisms by which the excited states are quenched by different molecules arc discussed, and rate-constant data compared with that for hcxafluoroacctonc
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    Vapour-phase Exciplex Formation between 1,4-Dicyanonaphthalene and 2,5-Dimethyl-2,4-hexadiene
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1981, 77 (06), 1981) Abbott, Geoffrey D; O’CoNNOR, Desmond V; Phillips, David
    Fluorescence has been observed from the exciplex formed between electronically excited 1,4-dicyanonaphthalene and 2,5-dimethyl-2,4-hexadiene in the vapour phase and the kinetics of exciplex formation studied. The enthalphy of vapour-phase exciplex formation in this pair of molecules was found to be 8 kJ mol–1 and activation energies for formation and reverse dissociation of the exciplex were found to be 15 and 23 kJ mol–1, respectively.