Gaining alignment

Freely suspended films provide a perfect homeotropic alignment of smectic LCs since the layers always orient parallel to the LC/air interface.33 The director structure in such films can then be determined by analyzing the optical properties of plane-polarized light reflected from the surface of the films at a slightly oblique angle.34 The technique gains additional power when electrodes are added to the setup, allowing observation of the behavior of the films in the presence of an electric field parallel to the plane of the film.35... 

A number of instrument variables need to be set prior to making measurements. These include slit, wavelength, lamp current, lamp alignment, amplifier gain, aspiration rate, burner head position, acetylene pressure, air pressure, acetylene flow rate, and air flow rate. Some instruments are rather automated in the setup process, while others are not. Your instructor will provide detailed instructions for the particular instrument you are using. Be sure to turn on the fume hood above the flame. 

Chemical facilities should investigate what networks and information sources might be available to them locally, and at the state and regional level. If a facility cannot gain access to some information networks, attempts should be made to align with those who can and will provide effective information to the chemical facility on a timely basis. 

Cao, J.R., Kuang, W., Choi, S.-J., Lee, P.-T., O Brien, J.D., Dapkus, P.D., 2003, Threshold dependence on the spectral alignment between the quantum-well gain peak and the cavity resonance in InGaAsP photonic crystal lasers, Appl. Phys. Lett. 83(20) 4107-4109. 

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