ELECTRIC-FIELD SPLITTING OF THE OCTATETRAENE 1 1AG -]2 1AG TRANSITION IN N-HEXANE

Octatetraene can be photoisomerized even when it is incorporated in a low temperature n-hexane crystal. When this is done by irradiating the zero-phonon component of the S0-->S1 origin band with a single frequency laser, very narrow (approximately 10 MHz) persistent holes can be burned. We have determined the effect of an externally applied electric field on these persistent holes and fit the observed data with a simple quantum mechanical model parameterized in the S0-->S2 and S1-->S2 transition dipoles and the magnitude of a molecular field intrinsic to the n-hexane site occupied by the octatetraene guest. The magnitude of the molecular field (approximately 10(6) V/cm) is consistent with only one of the three possible n-hexane sites that could have accommodated the octatetraene guest.