The Role of the Chromophore Size and Shape on the SHG Stability of PMMA Films with Embebbed NLO Active Macrocyclic Chromophores Based on a Cyclotetrasiloxane Scaffold

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• 作者：Marco Ronchi ; Alessio Orbelli Biroli ; Daniele Marinotto ; Maddalena Pizzotti ; M. Chiara Ubaldi ; Silvia M. Pietralunga
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：March 17, 2011
• 年：2011
• 卷：115
• 期：10
• 页码：4240-4246
• 全文大小：868K
• 年卷期：v.115,no.10(March 17, 2011)
• ISSN：1932-7455

文摘

In this work, the second harmonic generation (SHG) and the nonlinear optical (NLO) coefficients d₃₃ of PMMA films, containing 4 wt % NLO active macrocyclic chromophores based on a cyclotetrasiloxane scaffold and of their monomeric structurally homologous NLO active chromophores, were obtained by an electrical poling process and measured at room temperature during a period of many months, after switching off of the orienting electric field. The composite films based on the macrocyclic NLO chromophores have shown much higher d₃₃ values and stability in the time if compared to films based on the monomeric structurally homologous NLO chromophores. Such higher stability in the time is related to a higher decay time 蟿₂ and to a lower rotational diffusional coefficient D_R, as a consequence of the increased size of the macrocyclic NLO chromophores. We have observed that also the shape of the NLO chromophores may play a role. A good stability in the time of the d₃₃ values is maintained if the PMMA films, containing the macrocyclic NLO chromophores, are heated up to about 50 掳C.