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The application of intermolecular forces in LCD technology Content Introduction LCD History Structure of LCD monitor Intermolecular Force Permanent Diople moment Polarization The mechanism of LCD monitor Summary Group member list Introduction
liquid crystal which have permanent dipole moment line up in the electric field in LCD monitor. By the difference electric current, the LCD will display difference colours by the difference polarization of liquid crystal and the specific structure of the LCD monitor.
Solids act the way they do because their molecules always maintain their orientation and stay in the same position with respect to one another. The molecules in liquids are just the opposite: They can change their orientation and move anywhere in the liquid. But there are some substances that can exist in an odd state that is sort of like a liquid and sort of like a solid. When they are in this state, their molecules tend to maintain their orientation, like the molecules in a solid, but also move around to different positions, like the molecules in a liquid. This means that liquid crystals are neither a solid nor a liquid. That's how they ended up with their seemingly contradictory name.
So, do liquid crystals act like solids or liquids or something else? It turns out that liquid crystals are closer to a liquid state than a solid. It takes a fair amount of heat to change a suitable substance from a solid into a liquid crystal, and it only takes a little more heat to turn that same liquid crystal into a real liquid. This explains why liquid crystals are very sensitive to temperature and why they are used to make thermometers and mood rings. It also explains why a laptop computer display may act funny in cold weather or during a hot day at the beach!
The structure of LCD monitor just like a sunglasses. The liquid crystal is placed at the position of the polarizing film and it is placed between two electrodes. After each electrode is a polarization film. Ant the resistant coating is absent in the LCDs structure.
2 major types of intermolecular force :
H▬▬F - - - - - H▬▬F
Cl▬▬Cl - - - - - Cl▬▬Cl
Covalent bond (strong)
Van der Waals’ force
Following figures are demonstrating this polarisation dependence by means of confocal imaging of single fluorescein molecules randomly distributed on a glass surface. A single molecule shows up as a bright spot in the image.
Figures a) and b) show trace and retrace of the same scan area. The linear polarisation orientation of the excitation light was switched between a) vertical to b) horizontal polarisation (yellow arrows). Each polarisation direction selects a different set of molecules depending on the individual orientations of their absorption transition dipoles. Examples are highlighted by boxes, circles and triangles. Note that molecules having an absorption dipole along the optical axis cannot be excited in this set-up.
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