Two-dimensional spectroscopy of electrooptical response

一种新方法，用于second-order nonlinear after-effect function，已经开发了。Theoretical calculation starting from a general time-evolution equation connects nonlinear responsesin time domain and frequency domain那么gives the nonlinear response to applied external field of arbitrary form. In addition，it turns out in the frequency domain that the dc component of a second-order nonlinear responsefunction corresponds to a linear response function. for example，the dc component of the electric birefringence relaxation is equivalent to the dielectricrelaxation. This简单relation indicates an advantage of a frequency-domain measurement fornonlinear responses. As an example，electric birefringence relaxation is measured in two-dimensional frequency domain for aqueoussodium poly(styrenesulfonate) to confirm the validity of the theoretical results.Theabove electric birefringence is caused by the orientation of rodlike molecule without changing theshape under applied electric field. If the molecule can deform, however，elastic deformation due to electric field will also yield birefringence.自deformationhas a characteristic timeτ，the electric birefringence is expected to occur in the frequency region of τ D2-1 D2. By thefrequency-domain electrc birefringence spectroscopywe confirmed this prediction with water/AOT/isooctane (w/o) microemulsion，which has dispersed phase of spherical water droplet coated by the mono-layer surfactant of AOT in连续oil phase。

A new measurement method for second-order nonlinear after-effect function has been developed. Theoretical calculation starting from a general time-evolution equation connects nonlinear responses in time domain and frequency domain, and thus gives the nonlinear response to applied external field of arbitrary form. In addition, it turns out in the frequency domain that the dc component of a second-order nonlinear response function corresponds to a linear response function.For example, the dc component of the electric birefringence relaxation is equivalent to the dielectric relaxation. This simple relation indicates an advantage of a frequency-domain measurement for nonlinear responses. As an example, the electric birefringence relaxation is measured in two-dimensional frequency domain for aqueous solution of sodium poly(styrenesulfonate) to confirm the validity of the theoretical results.The above electric birefringence is caused by the orientation of rodlike molecule without changing the shape under applied electric field. If the molecule can deform, however, the elastic deformation due to electric field will also yield birefringence. Since the deformation has a characteristic timeτ, the electric birefringence is expected to occur in the frequency region of τィイD2-1ィエD2. By the frequency-domain electric birefringence spectroscopy, we confirmed this prediction with water/AOT/isooctane (w/o) microemulsion, which has dispersed phase of spherical water droplet coated by the mono-layer surfactant of AOT in continuous oil phase.