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21.
Pearton S. J. Abernathy C. R. Ren F. Lothian J. R. Kopf R. F. 《Plasma Chemistry and Plasma Processing》1994,14(4):505-522
Dry etching of common masking materials used in GaAs device technology, was examined down to temperatures of –30°C. The etch rates of SiNx, SiO2, and W in SF6/Ar are reduced below 0°C, but the anisotropy of the etching is improved at low temperature. Microwave enhancement of the SF6/Ar discharges produces increases in etch rates of several times at 25°C, but much lower increases at –30°C substrate temperature. The underlying GaAs surface shows increased S and F coverage after low-temperature etching, but these species are readily removerd either by anex-situ wet chemical cleaning step or an in-situ H2 plasma exposure. Photoresist etching is less sensitive to temperature, and anisotropic profiles are produced between –30 and +60°C in pure O2 discharges. 相似文献
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Nikhil Sharma Harry Abernathy Phillip N. First Thomas M. Orlando 《Surface science》2010,604(2):84-21624
Epitaxial graphene layers thermally grown on Si-terminated 6H-SiC (0 0 0 1) have been probed using Auger electron spectroscopy, Raman microspectroscopy, and scanning tunneling microscopy (STM). The average multilayer graphene thickness is determined by attenuation of the Si (L23VV) and C (KVV) Auger electron signals. Systematic changes in the Raman spectra are observed as the film thickness increases from one to three layers. The most striking observation is a large increase in the intensity of the Raman 2D-band (overtone of the D-band and also known as the G′-band) for samples with a mean thickness of more than ∼1.5 graphene layers. Correlating this information with STM images, we show that the first graphene layer imaged by STM produces very little 2D intensity, but the second imaged layer shows a single-Lorentzian 2D peak near 2750 cm−1, similar to spectra acquired from single-layer micromechanically cleaved graphene (CG). The 4-10 cm−1 higher frequency shift of the G peak relative to CG can be associated with charge exchange with the underlying SiC substrate and the formation of finite size domains of graphene. The much greater (41-50 cm−1) blue shift observed for the 2D-band may be correlated with these domains and compressive strain. 相似文献
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Background
The 5-HT3 receptor is a member of a neurotransmitter-gated ion channel family which includes nicotinic acetylcholine, GABAA, and glycine receptors. While antibodies specific for the 5-HT3A receptor subunit are plentiful, and have revealed a wealth of structural and functional information, few antisera exist for the detection of 5-HT3B receptor subunits. Here we describe the generation and characterisation of a rabbit polyclonal antiserum that specifically recognises 5-HT3B receptor subunits 相似文献26.
The reactivity of the 2,2′-, 2,4′-, 4,4′-dibenzyldiisocyanate (2,2′-, 2,4′-, 4,4′-DBDI) with n-butanol in benzene has been studied. The concentrations of all species were monitored by using high performance liquid chromatography (HPLC). The reactivity of 4,4′-DBDI is similar to that of 4,4′-diphenylmethanediisocyanate (4,4′-MDI). Very strong intramolecular catalytic effects were noticed in the case of 2,2′-DBDI, probably due to the variable molecular geometry. These effects are responsible for the whole reaction pattern. The 2,4′-DBDI NCO ortho and para groups reactivities are different and comparable to that of 2,4-toluylenediisocyanate (2,4-TDI). 相似文献
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Christianson AD Lumsden MD Delaire O Stone MB Abernathy DL McGuire MA Sefat AS Jin R Sales BC Mandrus D Mun ED Canfield PC Lin JY Lucas M Kresch M Keith JB Fultz B Goremychkin EA McQueeney RJ 《Physical review letters》2008,101(15):157004
We have studied the phonon density of states (PDOS) in LaFeAsO(1-x)Fx with inelastic neutron scattering methods. The PDOS of the parent compound (x=0) is very similar to the PDOS of samples optimally doped with fluorine to achieve the maximum Tc (x approximately 0.1). Good agreement is found between the experimental PDOS and first-principles calculations with the exception of a small difference in Fe mode frequencies. The PDOS reported here is not consistent with conventional electron-phonon mediated superconductivity. 相似文献
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Schussler-Langeheine C Weschke E Mazumdar C Meier R Grigoriev AY Kaindl G Sutter C Abernathy D Grubel G Richter M 《Physical review letters》2000,84(24):5624-5627
The magnetic splitting of Delta(2) valence states in the heavy lanthanide metals Gd, Tb, Dy, and Ho was studied in epitaxial films by angle-resolved photoemission, revealing an essentially Stoner-like temperature dependence in all cases. It scales linearly with the 4f spin moment, even in the case of the helical antiferromagnet Ho. Such a behavior can be explained by a substantial localization of the corresponding wave function in the c direction. The helical magnetic structure was confirmed for the thin Ho films by in situ resonant magnetic x-ray diffraction. 相似文献
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Abadie J Abbott BP Abbott R Abernathy M Accadia T Acernese F Adams C Adhikari R Ajith P Allen B Allen GS Ceron EA Amin RS Anderson SB Anderson WG Antonucci F Arain MA Araya MC Aronsson M Arun KG Aso Y Aston SM Astone P Atkinson D Aufmuth P Aulbert C Babak S Baker P Ballardin G Ballmer S Barker D Barnum S Barone F Barr B Barriga P Barsotti L Barsuglia M Barton MA Bartos I Bassiri R Bastarrika M Bauchrowitz J Bauer TS Behnke B Beker MG Belletoile A Benacquista M Bertolini A Betzwieser J 《Physical review letters》2011,107(27):271102
The gravitational-wave (GW) sky may include nearby pointlike sources as well as stochastic backgrounds. We perform two directional searches for persistent GWs using data from the LIGO S5 science run: one optimized for pointlike sources and one for arbitrary extended sources. Finding no evidence to support the detection of GWs, we present 90% confidence level (C.L.) upper-limit maps of GW strain power with typical values between 2-20×10(-50) strain(2)?Hz(-1) and 5-35×10(-49) strain(2)?Hz(-1)?sr(-1) for pointlike and extended sources, respectively. The latter result is the first of its kind. We also set 90% C.L. limits on the narrow-band root-mean-square GW strain from interesting targets including Sco X-1, SN 1987A and the Galactic center as low as ≈7×10(-25) in the most sensitive frequency range near 160 Hz. 相似文献
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Matthew R. Abernathy Gregory M. Harry Sheila Rowan Martin M. Fejer Steve Penn Andri Gretarsson 《Physics letters. A》2008,372(2):87-90
Second-generation interferometric gravitational-wave detectors will operate at temperatures noticeably above room temperature. Study was done to determine what effect elevated temperatures would have on the Q and coating thermal noise of the detector mirrors. Results show that increased temperature increases loss angle in a manner that is more significant at higher frequencies. Trends show that the increased temperature will have a negligible effect at the low (100 Hz) frequencies important to second-generation detectors. 相似文献