Identification and Role of Two-Photon Excited States in a <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>π</mi></math></span>-Conjugated Polymer

B. Lawrence; W. E. Torruellas; M. Cha; M. L. Sundheimer; G. I. Stegeman; J. Meth; S. Etemad; G. Baker

doi:10.1103/PhysRevLett.73.597

Identification and Role of Two-Photon Excited States in a $π$ -Conjugated Polymer

B. Lawrence, W. E. Torruellas, M. Cha, M. L. Sundheimer, G. I. Stegeman, J. Meth, S. Etemad, and G. Baker

Phys. Rev. Lett. 73, 597 – Published 25 July 1994

Abstract

We have measured the full two-photon absorption (TPA) spectrum in the transparency range of single-crystal polydiacetylene paratoluene-sulfonate (PTS) using $z$ scan. The spectrum consists of three well-defined two-photon excited states superimposed on a continuum of even-parity states. Comparison of the TPA and the one-photon absorption spectra identifies a two-photon accessible state as the lowest excited state of PTS. The accompanying dispersion in the intensity-dependent refractive index coefficient $n_{2}$ is also reported.