Theory of Intersystem Crossing in Aromatic Hydrocarbons

The electronic matrix elements governing intersystem crossing in aromatic hydrocarbons are derived and evaluated. The derivation is equivalent to Fano's treatment of resonance scattering. It is shown that the best first‐order description for crossings that show simple unimolecular behavior involves molecular states that are both spin contaminated and vibronically contaminated, but can be adequately represented by an expansion to second order in pure‐spin adiabatic Born‐Oppenheimer states. The corresponding first‐ and second‐order matrix elements are expanded about a nuclear equilibrium configuration and the expansions are terminated through the application of a symmetry argument. This yields five different types of matrix elements with small or vanishing cross terms; these matrix elements are associated with five experimentally distinguishable mechanisms, namely (1) direct spin‐orbit coupling, (2) vibronically induced spin‐orbit coupling, (3) mixed vibronic and spin‐orbit coupling, (4) resonant spin‐orbit...

[1]  W. Siebrand,et al.  Spin–Orbit Coupling in Aromatic Hydrocarbons. Analysis of Nonradiative Transitions between Singlet and Triplet States in Benzene and Naphthalene , 1971 .

[2]  Peter F. Jones,et al.  Temperature and Matrix Effects on the Phosphorescence Lifetime of Naphthalene‐d8 , 1969 .

[3]  D. Christensen,et al.  Analysis of the microwave spectrum of 2-fluoronaphthalene with a discussion of structure determination possibilities , 1962 .

[4]  E. C. Lim,et al.  'Inverse' deuterium isotope effect in radiationless electronic transitions, singlet → triplet intersystem crossing in anthracene , 1971 .

[5]  W. Siebrand.  Calculation of Franck–Condon Factors for Radiationless Transitions Based on Selective Excitation of Single Vibronic Levels , 1971 .

[6]  M. Stockburger,et al.  Resonance fluorescence and electronic relaxation in naphthalene vapor , 1971 .

[7]  B. Sharf.  Evidence for the 1/rij mechanism. Inhomogeneous line broadening in the Rydberg spectrum of naphthalene , 1971 .

[8]  M. Ratner,et al.  Spin-rotation effects on radiationless transitions , 1971 .

[9]  W. Siebrand.  On the relation between radiative and nonradiative transitions in molecules , 1971 .

[10]  R. S. Henderson.  Electron Spin Coupling in Polyatomic Molecules , 1955 .

[11]  W. Rhodes.  The nature of molecular excited states produced by weak light sources , 1971 .

[12]  R. Silbey,et al.  Fluorescence and Nonradiative Decay of Anthracene in Crystal and Solution , 1970 .

[13]  U. Fano.  Effects of Configuration Interaction on Intensities and Phase Shifts , 1961 .

[14]  H. Feshbach.  The unified theory of nuclear reactions: III. Overlapping resonances , 1967 .

[15]  G. Orlandi,et al.  Vibronic coupling and line broadening in polyatomic molecules , 1971 .

[16]  M. Orloff.  Theoretical Study of Triplet—Triplet Absorption Spectra. I. Alternant Hydrocarbon Molecules , 1967 .

[17]  E. W. Schlag,et al.  Lifetimes in Excited States , 1971 .

[18]  G. W. Robinson,et al.  Calculated Radiationless Transition Rates for Benzene and Deuterobenzene , 1969 .

[19]  R. Bennett,et al.  Radiationless Deactivation of the Fluorescent State of Substituted Anthracenes , 1966 .

[20]  Rudolph Pariser,et al.  Theory of the Electronic Spectra and Structure of the Polyacenes and of Alternant Hydrocarbons , 1956 .

[21]  W. Siebrand,et al.  Theory of electron spin alignment through nonradiative processes in naphthalene and anthracene , 1970 .

[22]  B. Stevens,et al.  Double intersystem-crossing in naphthalene and 1-chloronaphthalene , 1968 .

[23]  A. Nitzan,et al.  Optical Selection Studies of Radiationless Decay in an Isolated Large Molecule , 1971 .

[24]  A. Messiah.  Quantum Mechanics , 1961 .

[25]  Digby F. Williams,et al.  Radiationless Transitions in Polyatomic Molecules. III. Anharmonicity, Isotope Effects, and Singlet‐to‐Ground‐State Transitions in Aromatic Hydrocarbons , 1968 .

[26]  J. Hollas,et al.  Analysis of the naphthalene vapour absorption bands at 3200Å. I. Naphthalene h-8 , 1961, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.

[27]  E. C. Lim,et al.  Electronic relaxation in naphthalene vapor , 1970 .

[28]  K. Freed,et al.  Radiative Decay of Polyatomic Molecules , 1969 .

[29]  P. Wannier,et al.  Small molecule characteristics of the radiative decay of highly excited states of some large molecules , 1971 .

[30]  W. T. Raynes.  Spin Splittings and Rotational Structure of Nonlinear Molecules in Doublet and Triplet Electronic States , 1964 .

[31]  R. E. Kellogg.  Second Triplet State of Anthracene , 1966 .

[32]  R. Silbey,et al.  On the effect of deuteration on non-radiative processes in large molecules☆ , 1970 .

[33]  R. Silbey,et al.  Near resonance interactions in the B-O scheme. The vibronic mechanism pertinent to radiationless transitions and inhomogeneous line broadening , 1971 .

[34]  W. Gelbart,et al.  On the Born—Oppenheimer separation and the calculation of nonradiative transition rates , 1971 .

[35]  W. Siebrand.  Radiationless Transitions in Polyatomic Molecules. II. Triplet‐Ground‐State Transitions in Aromatic Hydrocarbons , 1967 .

[36]  R. Lefebvre.  Preparation and decay of initial states in intramolecular radiationless processes , 1971 .

[37]  R. Clarke.  Magnetic resonance studies of the deuteration effect on intersystem crossing in the anthracene molecule , 1971 .

[38]  S. Fischer,et al.  Where does the energy go for radiationless transitions? The 3B1u ⇝ 1A1g transition for benzene and deuterobenzene , 1971 .

[39]  Joshua Jortner,et al.  Intramolecular Radiationless Transitions , 1968 .