2-PHOTON ABSORPTION RESONANCE IN 1-DICYANOETHENYL)-1-PHENYL-4,5-DIHYDRO-1H-PYRAZOLE (DCNP)

A two-photon absorption spectrum of 1-dicyanoethenyl)-1-phenyl-4,5-dih ydro-1H-pyrazole (DCNP) in tetrahydrofuran solution has been studied b y the Kerr ellipsometry technique. The spectral shape and amplitude of the imaginary part of the dominant molecular hyperpolarizability term Im(gamma(xxxx)) is compared with the relevant linear absorption spect rum within a simple two-level model. Agreement between the measured ga mma(xxxx) = 2.0 x 10(-?(48) m(5) V-?(2 and calculated gamma(xxxx) = (1 .2-1.5) x 10(-?(48) m(5) V-?(2 two-photon absorption molecular hyperpo larizabilties in the vicinity of the two-photon resonance transition i s satisfactory. (C) 1998 Elsevier Science B.V. All rights reserved.