Bulletin of the American Physical Society
2005 TSAPS/AAPT/SPS Joint Fall Meeting
Thursday–Saturday, October 20–22, 2005; Houston, TX
Session B1: Condensed Matter II |
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Room: Shamrock Main 261M |
Friday, October 21, 2005 2:00PM - 2:12PM |
B1.00001: A simple technique for spectral control of a mode-locked Ti:Sapphire oscillator Jiahui Peng, Alexei Sokolov Synchronous multiple wavelengths and tunable lasing has attracted wide interesting, especially in the frequency mixing and pump-probe experiments. Great interests have been shown in the multi-wavelength operation of the mode-locked Ti:sapphire (TS) laser because of the broad bandwidth and short pulse it can generate. In these previous reports, dual-wavelength was obtained either by manipulating the gain spectrum or dispersion of laser cavity. All the work employing two cavities system face the problem that the two cavities will have to be adjust to same repetition rate, so that one mirror not only needs to be adjustable, but also needs to be adjusted carefully to achieve synchronization. We describe a simple technique to control spectrum, and then generate dual-wavelength of a mode-locked TS laser in a single cavity based on the mechanism of dispersion control, which can generate much wider spectrum bandwidth and much wider separation of two pulses compared with previous work. We also have Tri-wavelength generated in blue range after SHG and SFG with a LBO crystal. [Preview Abstract] |
Friday, October 21, 2005 2:12PM - 2:24PM |
B1.00002: Dielectric Response of Gallium Arsenide ( GaAs), Lead Zirconate Titanate (PZT) and Other Select Materials in a Microwave Field James Roberts, Aman Anand, Jai Dahiya A cylindrical microwave resonant cavity mode was used to study the response of select materials undergoing microwave response over temperature. The microwave response of some semiconductor materials was studied by using a raw as well as a ground sample. The sample were placed in a fine capillary tube, which in turn was placed into the microwave field of the resonant cavity. The cavity was cooled over the desired temperature by using liquid nitrogen heat exchanger with the temperature continually monitored with a thermocouple. The resonant signal of the microwave cavity was displayed on an oscilloscope and recorded in a computer, along with the temperature from the thermocouple, for future analysis. This process eliminates any errors being introduced in the frequency shifts and the width changes being recorded at various temperatures. Slater's perturbation equations were used to calculate the dielectric constant of each sample as a function of temperature at several microwave frequencies [Preview Abstract] |
Friday, October 21, 2005 2:24PM - 2:36PM |
B1.00003: Magnetic Reversal in NiFe Gratings Joel Dunn, Wilhelmus Geerts, Gregory Spencer, Claude Garrett, Jett Hendrix Well-characterized magnetic properties of NiFe films are important for the understanding of the magnetic reversal process and the optimization of the performance of the devices that rely on them (i.e. magnetic recording heads, position/angle sensors, etc.). Gratings were wet etched into NiFe films and were then characterized using Kerr Magnetometry, Profilometry, and Kerr Microscopy. The gratings consisted of 1-10 $\mu$m wide strips with triangle or mesa shaped cross-sections. It was discovered that the domain in the center of the strips reversed at lower fields than the domains in the pitched sidewalls. The hysteresis curves of the gratings showed a two-stepped magnetic reversal process: a sharp reversal at low fields and a gradual reversal at higher fields. This resulted in ``sleeves'' in the hysteresis curve that were in contrast with the sharp domain reversal of the unpatterned/unetched film. It was concluded that the wet etching process had changed the magnetic properties of the film, possibly by selective etching of either the Fe or Ni in the alloy. [Preview Abstract] |
Friday, October 21, 2005 2:36PM - 2:48PM |
B1.00004: Auger Parameter of Aluminum Richard Miller, A. Chourasia, George Nixon X-ray photoelectron spectroscopy has been employed to determine the Auger parameter of aluminum using the 1s core level. For this purpose the zirconium anode (energy = 2042 eV) has been employed. XPS spectra in the aluminum 1s core level and the X-ray excited Auger region were recorded in a high resolution mode. The modified Auger parameter is defined as the energy difference between the XPS core level and the intense line in the Auger region plus the energy of the x-rays. This parameter then becomes independent of the x-ray source used and provides a powerful tool to identify the chemical states. In this investigation we have studied elemental aluminum. aluminum oxide, aluminum halides, aluminum boride, and aluminum carbide. The Wagner plots for these materials have been constructed. The importance of the Auger parameter in determining the bonding characteristics of aluminum will be discussed. [Preview Abstract] |
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