Bulletin of the American Physical Society
Spring 2011 Meeting Ohio-Region Section of the APS
Volume 56, Number 3
Friday–Saturday, April 15–16, 2011; University Heights, Ohio
Session D1: Applied Physics; Atomic, Molecular and Optical Physics |
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Chair: Kathleen Kash, Case Western Reserve University Room: Dolan Science Center E120 |
Saturday, April 16, 2011 8:10AM - 8:22AM |
D1.00001: Health Related Aspects of Artificial Light Richard Hansler, Vilnis Kubulins, Edward Carome It was long thought that the ``sleep hormone,'' melatonin, is produced by the pineal gland only when the eyes are in darkness. Thus, in developed countries, due to the use of electric lighting after dark, melatonin production usually occurs only when one is asleep. For most people, this is substantially less than the 9 to 10 hour production time capability of the pineal gland. However, in 2001 it was discovered that not all light, but mainly a band of wavelengths in the blue portion of the spectrum, below 530nm, suppresses melatonin production. On learning this, and that melatonin is a very active cancer fighting antioxidant and has many other health promoting properties, it was decided to make available lighting products that can enhance melatonin production. Included are lamps that do not emit the offending blue wavelengths and eyeglasses that filter out the blue portion of the spectrum. These and other related products are meant to be used for several hours in the evening, before retiring, thus maximizing the pineal gland's production time. The effects of their use on sleep and several other health related conditions are discussed. [Preview Abstract] |
Saturday, April 16, 2011 8:22AM - 8:34AM |
D1.00002: Development of LED Lamps for Airfield Applications Edward Carome, Richard Hansler, Vilnis Kubulins Extensive work is being done to develop light emitting diode (LED) lamps to replace the incandescent lamps in the many different lights used on airfield runways and taxiways. The goal is to reduce both the expended energy and the lifetime cost of such lights. Consider, for example, the blue lights used along taxiways. Traditionally these consisted of a 40 watt incandescent lamp in a blue light transmitting lens. These are being replaced with lamps with a single 1 to 3 watt blue LED. The design of one such lamp will be discussed, as will that of several types of runway lights. A major problem has developed in this switch from incandescent to LED lamps, however. The previously wasted IR from the incandescents has recently come into use by so-called Enhanced Flight Vision Systems (EFVS). These systems provide pilots images of the IR from runway lights and allow them to land under highly adverse weather conditions. Since the new LED lamps emit very little IR, they cannot be imaged by these EFVS. Solutions of this problem, such as adding infrared LEDs to the new lamps, presently are being investigated and will be discussed. [Preview Abstract] |
Saturday, April 16, 2011 8:34AM - 8:46AM |
D1.00003: Broadening the Interface Between a Compensation Film and Its Substrate in a Direct Coating Process Wumin Yu, Mark Foster Rigid-rod like aromatic polyimides (PIs) have been used as compensation films to widen viewing angles of liquid crystal displays (LCDs). A new procedure for incorporating the compensation film in the multilayer LCD assembly by directly coating the PI on a substrate film, e.g. triacetate cellulose (TAC), is preferred in industry for its simplicity and cost-effectiveness. Based on experimental results from other systems, it is thought that the adhesion of the PI layer to the TAC substrate should increase with increasing width of the interface between the two. To probe the interface width, sequential solution deposition processes were used to create model bilayer structures. Neutron Reflectivity measurements reveal that the interface width can be substantially increased by depositing the PI layer using a solvent mixture that includes a component which swells the TAC. Since changing coating temperature impacts multiple transport rates, there exists an optimum deposition temperature to maximize interface width. [Preview Abstract] |
Saturday, April 16, 2011 8:46AM - 8:58AM |
D1.00004: Cathodoluminescence Study of Undoped and Mn Doped Lithium Tetraborate Crystals Being Developed for Neutron Detection Christina Dugan, Robert Hengehold, John McClory Lithium tetraborate or LTB crystals are being developed for possible use in solid state neutron detectors. Already used in thermo luminescence dosimeters, LTB is of interest due to its large cross section for neutron capture by lithium and boron. The reaction between lithium and a neutron produces an alpha particle and tritium. When boron interacts with a neutron an alpha particle and lithium are produced. These reactions are the basis for neutron detection, and a LTB crystal enriched with Mn should show improved efficiency for such detection. There is, however, a lack of fundamental characterization information regarding this useful material, particularly with regard to its electronic configuration. In this study, cathodoluminescent spectroscopy has been used to determine the energy level structure of undoped and manganese doped lithium tetraborate crystals. Measurements were made at various beam energies from 5 to 10 KeV on samples maintained at room temperature. Self trapped exciton emission states are evident in the undoped and Mn doped LTB samples ranging in energies from 2.5 to 4.1 eV. [Preview Abstract] |
Saturday, April 16, 2011 8:58AM - 9:10AM |
D1.00005: InAs Nanowire Transistors as Gas Sensor: the Role of Surface States Dong Liang, Juan Du, Hao Tang, Xuan P.A. Gao Utilizing the large surface-to-volume ratio, sensors of quasi one-dimensional semiconductor nanowires based electronic devices have been shown high sensitivity to the adsorption gaseous molecules or the binding of biomolecules in liquid, enabling a label-free sensing modality with high sensitivity and direct electrical readout. We report a study of the response of InAs nanowire field-effect transistor sensor devices to various gases and alcoholic vapors. It is concluded that the change in conductance of the device in response to chemical vapors is a combined result of both the charge transfer and modified electron mobility effects. In particular, we found that surface adsorption of most chemical molecules can reduce electron density in nanowires from $\sim $10$^{4}$ to $\sim $10$^{3}$/$\mu $m and enhance the electron mobility greatly (from tens to a few hundred of cm$^{2}$/(V s)) at the same time. These effects are attributed to the interactions between adsorbed molecules and the electron accumulation layer and rich surface states on the InAs nanowire surface. Journal reference: Nano Letters 9, 4348 (2009). [Preview Abstract] |
Saturday, April 16, 2011 9:10AM - 9:22AM |
D1.00006: The Verdet constant of undoped Y$_3$Al$_5$O$_{12}$ in the near infrared at a fixed temperature Ronald W. Stites, Kenneth M. O'Hara The optical activity of an undoped Y$_3$Al$_5$O$_{12}$ (YAG) crystal in a magnetic field is measured in the near infrared at a fixed temperature. By knowing the integrated field strength along the optical axis of the crystal, the Verdet constant is determined for wavelengths from 1300 nm to 1350 nm as well as at 1064 nm and compared to theory. For the 1300 nm range, the Verdet constant is found to be of the order 0.84 rad/T$\cdot$m while at 1064 nm it is 1.86 rad/T$\cdot$m. [Preview Abstract] |
Saturday, April 16, 2011 9:22AM - 9:34AM |
D1.00007: Quantum Optics Models of EIT Noise and Power Broadening Chad Snider, Michael Crescimanno, Shannon O'Leary When two coherent beams of light interact with an atom they tend to drive the atom to a non-absorbing state through a process called Electromagnetically Induced Transparency (EIT). If the light's frequency dithers, the atom's state stochastically moves in and out of this non-absorbing state. We describe a simple quantum optics model of this process that captures the essential experimentally observed statistical features of this EIT noise, with a particular emphasis on understanding power broadening. [Preview Abstract] |
Saturday, April 16, 2011 9:34AM - 9:46AM |
D1.00008: Co-extruded mechanically tunable multilayer elastomer laser Michael Crescimanno, Guilin Mao, James Andrews, Kenneth Singer, Eric Baer, Anne Hiltner, Hyunmin Song, Bijayandra Shakya We have fabricated and studied mechanically tunable elastomer dye lasers constructed in large area sheets by a single-step layer-multiplying co-extrusion process. The laser films consist of a central dye-doped (Rhodamine-6G) elastomer layer between two 128-layer distributed Bragg reflector (DBR) films comprised of alternating elastomer layers with different refractive indices. The central gain layer is formed by folding the coextruded DBR film to enclose a dye-doped skin layer. By mechanically stretching the elastomer laser film from 0{\%} to 19{\%}, a tunable miniature laser source was obtained with $\sim $50 nm continuous tunability from red to green. [Preview Abstract] |
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