Substituent Effects on the Second Hyperpolarizability of Thioxanthen–9–one and Its Derivatives

Abstract

The third–order nonlinear optical susceptibilities (χ⁽³⁾) of thioxanthen–9–one (3) and its derivatives having 1,4-dimethyl (5), 2,4-dimethyl (6), 1,4-dimethoxy (7), or 2-methoxy-7-nitro (8) substituents were measured by a degenerate four-wave mixing (DFWM) technique with 7-ns pulses at 532 nm in THF and/or CH₂Cl₂ solutions. Their second hyperpolarizabilities (γ) widely vary in a range from 2.1 × l0⁻³⁴ to 2.7 × 10⁻³² esu depending on their substituents.