Kevin D. Cadogan

Bio: Kevin D. Cadogan is an academic researcher. The author has contributed to research in topics: Absorption spectroscopy & Ionization. The author has an hindex of 2, co-authored 2 publications receiving 73 citations.

Organic mixed valence.

Abstract: 3.3. Influence of the Bridge Redox States 5159 4. Multidimensional Organic Mixed Valence 5163 5. Intervalence Charge Transfer across Noncovalent Pathways 5167 6. Use of EPR Spectroscopy as a Direct Test for Hush Theory 5170 7. Solvent and Ion Pairing Effects 5171 8. Crystallographic Studies 5173 9. Concluding Remarks 5175 Author Information 5175 Biographies 5175 Acknowledgment 5176 References 5176

An electron-tunnelling model for recombination of aromatic hydrocarbon radical ions in non-polar solvents

Abstract: An electron-tunnelling model is used to describe the recombination of ions such as (naphthalene)+ with anions or solvated electrons in alkanes; theoretical difficulties and estimation of the barrier height are discussed. Recombination in solids can take place over large distances (∼ 50 A). Transfer distances in liquids are obtained by comparing the rate of approach of the ions with the tunnelling rate: in viscous liquids, the distances are again large — the ions do not make contact. A new tunnelling formula is constructed which incorporates Franck—Condon factors; it is used for illustrative calculations of the relative rate constants for production of excited singlets and triplets. Tunnelling rates and the overall recombination time are compared with spin-relaxation rates to assess the probability of variations in the singlet—triplet ratio; possible effects of viscosity and external magnetic fields are discussed.

Two-color, photon-gated spectral hole-burning in an organic material

Abstract: We report the first observation of two-color, photon-gated spectral hole-burning in an organic system: carbazole in boric acid glass. This novel hole-burning mechanism involves stepwise biphotonic photoionization of carbazole at 1.4 K. The quantum yield for photoionization increases exponentially with the energy of the second photon.

Vibrational studies of reactive intermediates of aromatic amines. IV. Radical cation time‐resolved resonance Raman investigation of N, N‐dimethylaniline and N, N‐diethylaniline derivatives

Abstract: The radical cation time‐resolved resonance Raman spectra of various isotopic derivatives of N, N‐dimethylaniline (DMA), N, N‐diethylaniline (DEA), N, N‐dimethyl‐p‐toluidine (4MDMA) and 3, 5, N, N‐tetramethylaniline (3,5DMDMA) are reported in the 300–1800 cm−1 range. Excitation was in the weak radical cation absorption around 480 nm. Complete vibrational assignments are proposed. The band activity and the changes in frequency with respect to the neutral molecules are consistent with a quinoidal‐type conformation of the framework close to planarity. Stabilization of this conformation is observed when the phenyl ring contains methyl substituents. The analysis of the Raman enhancements suggests that the quinoidal character of the radical structure is significantly lowered in the resonant excited state. An obvious analogy is found between the spectra of DMA+ ⋅ and of the biphenyl radical cation, which clearly indicates that (i) a nearly common chromophore structure characterizes these two radical cations and (...