Molecular Orientational Distribution at Interfaces Using Second Harmonic Generation

作者：Rao Yi; Hong Sung Young; Turro Nicholas J; Eisenthal Kenneth B^*

来源：Journal of Physical Chemistry C, 2011, 115(23): 11678-11683.

DOI：10.1021/jp202546b

We present a novel method for obtaining the orientational distribution of molecules at the air/water interface by using a circularly polarized pump pulse that is incident normal to the interface to excite interfacial molecules to their excited electronic states. The second harmonic generation intensities of two linearly polarization combinations (45 degrees-in/S-out and P-in/P-out) were measured. The ratio of their intensities measured before and after the pump pulse was then used to obtain the mean orientational angle and the orientational distribution utilizing a Gaussian distribution. The mean orientational angle and the orientational distribution of the organic dye molecule, coumarin 314, at the air/water interface were found to be 55 +/- 2 degrees with respect to the surface normal and a full width at half-maximum of 16 +/- 3 degrees.

• 出版日期2011-6-16