研究目的
Investigating the first hyperpolarizabilities of mesoionic compounds dissolved in dimethyl sulfoxide (DMSO) using Hyper-Rayleigh scattering experiments.
研究成果
Generation of incoherent optical second harmonic (hyper-Rayleigh scattering) was observed in the mesoionic compounds dissolved in DMSO. The hyper-Rayleigh scattering technique was applied for determination of the first hyperpolarizability associated to the samples and the results indicate that ???(2??)?~ 10?29 ??????. The disagreement observed with the previous theoretical predictions may stimulate further theoretical and numerical calculations for the studied compounds.
研究不足
The disagreement observed with the previous theoretical predictions may stimulate further theoretical and numerical calculations for the studied compounds, including features associated to the liquid phase that are relevant in real systems.
1：Experimental Design and Method Selection:
Hyper-Rayleigh scattering (HRS) technique was employed to evaluate the magnitude of ??(2??) per molecule of the MICs dissolved in DMSO. The NL optical coefficient was determined by measuring the intensity of the incoherent second harmonic signal generated by the sample upon excitation using a laser off-resonance with molecular transitions.
2：Sample Selection and Data Sources:
The powders were dissolved in DMSO with concentrations of 1.80 x 10^19 (MIC-1), 1.96 x 10^19 (MIC-2) and 1.58 x 10^19 (MIC-3) molecules per cm3 for the experiments.
3：80 x 10^19 (MIC-1), 96 x 10^19 (MIC-2) and 58 x 10^19 (MIC-3) molecules per cm3 for the experiments.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: An Optical Parametric Oscillator (OPO) –
4：5 ns, 20 Hz – pumped by a Q-switched Nd:
YAG laser was used as the excitation source. The OPO wavelength was kept at 1180 nm for all measurements. A 5 cm focal lens focused the laser beam on the liquid solution that was inside a 1 cm long quartz cuvette.
5：Experimental Procedures and Operational Workflow:
The scattered light was collected perpendicularly to the laser beam direction by a set of two 5 cm focal length lenses. Filter 2 was an interference filter centered at 590 nm with full width at half maximum (FWHM) of 8 nm. The collected light was focused on a photomultiplier connected to an oscilloscope and the signal was analyzed using a personal computer.
6：Data Analysis Methods:
The ???(2??)? values for all MIC samples were determined using the external reference method (ERM). The present results were analyzed using the two-level model approximation.
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