表面穩定強誘電性液晶之隨機過程

Abstract

在統計力學中，擾動耗散定律揭開了分子熱擾動的存在及其重要性。然而，這看似雜訊般的信號背後隱藏的資訊卻鮮為人知。本論文的主旨著重在探討特定凝態材料- 鐵電相液晶分子及其摻雜氧化鋅奈米微晶的動態行為(或稱表面穩定強誘電性液晶)。 液晶方向矢的擾動是由液晶材料特性所決定。因此本論文從液晶擾動方程與其對應的動態散射光開始，在經由探測散射光訊號的自我相關函式得到與鐵電相液晶的物理參數之相關性，並配合動態光散射實驗確認摻雜氧化鋅奈米微晶之表面穩定強誘電性液晶，其整體液晶分子排列較佳，此特徵可從熱擾動的表現改變而發覺，並可歸因於材料特性的變動;此外，摻雜氧化鋅奈米微晶之表面穩定強誘電性液晶在外加相同驅動電場下，擁有比未摻雜之強誘電性液晶元件快的反應速度。

The fluctuation-dissipation theorem unveils the importance of thermal molecular motion which always exists, even in thermal equilibrium, as a fluctuation. However, the underlying information of thermal fluctuation which appears to be random noise is a huge question mark that had been overlooked for years. This thesis study focuses on the discussion about the dynamics of molecular fluctuations in a specific condensed matter- the ferroelectric liquid crystals (FLC) with and without doping of nanocrystal ZnO. The dynamics of orientation director fluctuations is governed by the material properties of the liquid crystal. In this thesis, we first derive the relation between the scattered light intensity and fluctuations of the FLC director which, through some reasonable assumption, could be described as a stochastic equation of motion. After performing autocorrelation technique to the scattered light signals, we have come to realize that the internal fluctuation is characterized by a correlation function of relevant physical quantities of the FLC system fluctuating in thermal equilibrium. The measurement results lead to the fact of improved molecular alignment and faster response time in the SSFLC cell doped with ZnO nanocrystals.