| Abstract
| - The intramolecular electron hopping in cation dimer radicals of 1,n-bis(N-carbazolyl) alkanes for n = 3,4that are produced via photoinduced electron transfer to 1,4-dicyanobenzene (DCNB) has been studied bymeans of the exciplex fluorescence detected magnetic field effect (MFE) in a 18 vol % mixture ofdimethylformamide with tetrahydrofuran. It has been found that on passing from a single cation radical ofN-methylcarbazole to the cation dimers, the parameter B1/2 decreases from ca. 50 G to ca. 26 G, while saturationvalues of MFE (at B = 300 G) are almost the same (ca. 3.0% for MeCz and CzB) but strongly decreased forCzP (ca. 0.5%). The experimental results obtained are in fair agreement with the Schulten theory ofintramolecular electron exchange. In contrast to the well-known pyrene/N,N-dimethylaniline exciplex system,the carbazole derivatives/DCNB system exhibits a two-exponential decay of exciplex fluorescence and asignificantly smaller MFE that might result from the fact that in the latter exciplex system the radical ion pairstate is the lowest energy state above the ground state.
|
