Material Type  

 학위논문

 

0017164030

Date and Time of Latest Transaction  

20250211152823

ISBN  

9798384095552

DDC  

541

Author  

Wu, Zhihao.

Title/Author  

Interfacial Structure in Thermotropic Liquid Crystals as Studied by Vibrational Sum Frequency Generation Spectroscopy.

Publish Info  

[S.l.] : University of Minnesota., 2024

Publish Info  

Ann Arbor : ProQuest Dissertations & Theses, 2024

Material Info  

125 p.

General Note  

Source: Dissertations Abstracts International, Volume: 86-03, Section: B.

General Note  

Advisor: Massari, Aaron M.

학위논문주기  

Thesis (Ph.D.)--University of Minnesota, 2024.

Abstracts/Etc  

요약Liquid crystals (LCs) are widely used in many optoelectronic devices. The study of LC interfaces is critical for understanding the molecular interactions within the LC devices and improving the device performance. Air-LC, liquid-LC, and polymer-LC interfaces have been extensively studied in the literature, however, the molecular orientation and ordering of the thermotropic LCs and solid interfaces remain underexplored. Emerging LC alignment techniques, such as nanopatterning, oblique evaporation, and photo-induced alignment, show the need for in-depth studies of solid-LC interfaces. In this work vibrational sum frequency generation spectroscopy (VSFG), a second-order nonlinear optical technique, was used to study the orientation of the interfacial LC molecules on solid substrates. Chapter 1 introduces the basics of LCs and LC devices, discussing the importance of solid-LC interfaces. Chapter 2 covers the theoretical background and experimental setup of VSFG. Chapter 3 discusses the design of sample cells and the considerations necessary for conducting temperature-controlled and voltage-controlled VSFG experiments. Chapter 4 presents a detailed study of the solid-LC interfaces of thermotropic 8CB LCs using VSFG and X-ray reflectivity (XRR), comparing the bulk and interfacial LC behaviors across different phases. Chapter 5 explores the interfacial molecular behavior of nematic LCs 5CB under an applied voltage in a working LC sample cell. Nickel ultra-thin metallic film (UTMF) was used as transparent electrode for the first time in a VSFG experiment.

Subject Added Entry-Topical Term  

Physical chemistry.

Subject Added Entry-Topical Term  

Chemistry.

Subject Added Entry-Topical Term  

Applied physics.

Subject Added Entry-Topical Term  

Optics.

Index Term-Uncontrolled  

Liquid crystals

Index Term-Uncontrolled  

Solid-LC interfaces

Index Term-Uncontrolled  

Spectroscopy

Index Term-Uncontrolled  

Sum frequency generation

Index Term-Uncontrolled  

Thermotropic LCs

Added Entry-Corporate Name  

University of Minnesota Chemical Physics

Host Item Entry  

Dissertations Abstracts International. 86-03B.

Electronic Location and Access  

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Control Number  

joongbu:654414