Diode laser stark spectroscopy on the persistent holes

The Stark effect on the hole-burning spectra of Zn- and Mg-phthalocyanine (Zn-, Mg-PhC) in polyvinylbutyral (PVB) films at 4.2 K have been measured using a tunable diode laser technique in the visible region. Simultaneously, with a linear Stark effect, a quadratic effect was also recorded. From comparison of the experimental data with the results of model calculations, the Stark parameters for both systems and a value of the internal electric field in polymer matrix were deduced. For Zn-PhC in PVB, we obtained average values of the induced dipole moment difference between ground and excited states: Δμind=0.105 D; the polarizability tensor difference: Δα=62 Å3; average local field value: Ei=7×105 V cm−1. For Mg-PhC in PVB: Δμind=0.095 D, Δα=50 Å3 and Ei=6.5×105 V cm−1.