Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Discipline
- Institution
- Publication Year
- Publication
- Publication Type
Articles 1 - 25 of 25
Full-Text Articles in Physical Sciences and Mathematics
Investigation Of The Physical And Electronic Properties Of Indium Doped Zinc Oxide Nanofibers Synthesized By Electrospinning, A. F. Lotus, Y. C. Kang, R. D. Ramsier, George G. Chase
Investigation Of The Physical And Electronic Properties Of Indium Doped Zinc Oxide Nanofibers Synthesized By Electrospinning, A. F. Lotus, Y. C. Kang, R. D. Ramsier, George G. Chase
George G Chase
Nanostructured metal oxides and particularly nanofiber based materials can provide significant advances for the miniaturization of electronic, optoelectronic, photonic, sensor, and energy conversion devices with enhanced performance based on their unique material properties. In this study, indium doped zinc oxide (IZO) nanofibers were synthesized by electrospinning. These nanofibers have diameters in the range 50-100 nm. The effects of indium addition on the structural, optical, and electrical properties of the zinc oxide nanofiber matrices were investigated. The IZO nanofibers undergo significant changes in their optical and electrical properties compared to undoped zinc oxide nanofibers.
Negative Index Metamaterials Based On Metal-Dielectric Nanocomposites For Imaging Applications, L. Menon, W. T. Lu, A. L. Friedman, S. P. Bennett, D. Heiman, S. Sridhar
Negative Index Metamaterials Based On Metal-Dielectric Nanocomposites For Imaging Applications, L. Menon, W. T. Lu, A. L. Friedman, S. P. Bennett, D. Heiman, S. Sridhar
Srinivas Sridhar
Negative index metamaterials are demonstrated based on metal-dielectric nanocomposites prepared using a versatile bottom-up nanofabrication approach. The method involves the incorporation of vertically aligned metal nanowires such as Au and Ag inside dielectric aluminum oxide nanotemplates. Optical absorbance measurements show resonance peaks corresponding to the transverse and longitudinal surface plasmon modes. A quantitative model based on effective medium theory is in excellent agreement with experimental data, and points to specific composite configurations and wavelength regimes where such structures can have applications as negative refraction media for imaging.
Negative Index Metamaterials Based On Metal-Dielectric Nanocomposites For Imaging Applications, L. Menon, W. T. Lu, A. L. Friedman, S. P. Bennett, D. Heiman, S. Sridhar
Negative Index Metamaterials Based On Metal-Dielectric Nanocomposites For Imaging Applications, L. Menon, W. T. Lu, A. L. Friedman, S. P. Bennett, D. Heiman, S. Sridhar
Donald Heiman
Negative index metamaterials are demonstrated based on metal-dielectric nanocomposites prepared using a versatile bottom-up nanofabrication approach. The method involves the incorporation of vertically aligned metal nanowires such as Au and Ag inside dielectric aluminum oxide nanotemplates. Optical absorbance measurements show resonance peaks corresponding to the transverse and longitudinal surface plasmon modes. A quantitative model based on effective medium theory is in excellent agreement with experimental data, and points to specific composite configurations and wavelength regimes where such structures can have applications as negative refraction media for imaging.
Negative Index Metamaterials Based On Metal-Dielectric Nanocomposites For Imaging Applications, L. Menon, W. T. Lu, A. L. Friedman, S. P. Bennett, D. Heiman, S. Sridhar
Negative Index Metamaterials Based On Metal-Dielectric Nanocomposites For Imaging Applications, L. Menon, W. T. Lu, A. L. Friedman, S. P. Bennett, D. Heiman, S. Sridhar
Latika Menon
Negative index metamaterials are demonstrated based on metal-dielectric nanocomposites prepared using a versatile bottom-up nanofabrication approach. The method involves the incorporation of vertically aligned metal nanowires such as Au and Ag inside dielectric aluminum oxide nanotemplates. Optical absorbance measurements show resonance peaks corresponding to the transverse and longitudinal surface plasmon modes. A quantitative model based on effective medium theory is in excellent agreement with experimental data, and points to specific composite configurations and wavelength regimes where such structures can have applications as negative refraction media for imaging.
Time Evolution Of The Reverse Shock In Sn 1006, P. Frank Winkler, Andrew J. S. Hamilton, Knox S. Long, Robert A. Fesen
Time Evolution Of The Reverse Shock In Sn 1006, P. Frank Winkler, Andrew J. S. Hamilton, Knox S. Long, Robert A. Fesen
Dartmouth Scholarship
The Schweizer-Middleditch star, located behind the SN 1006 remnant and near its center in projection, provides the opportunity to study cold, expanding ejecta within the SN 1006 shell through UV absorption. Especially notable is an extremely sharp red edge to the Si II 1260 Å feature, which stems from the fastest moving ejecta on the far side of the SN 1006 shell—material that is just encountering the reverse shock. Comparing Hubble Space Telescope far-UV spectra obtained with the Cosmic Origins Spectrograph in 2010 and with the Space Telescope Imaging Spectrograph in 1999, we have measured the change in this feature …
Investigation Of The Physical And Electronic Properties Of Indium Doped Zinc Oxide Nanofibers Synthesized By Electrospinning, A. F. Lotus, Y. C. Kang, R. D. Ramsier, George G. Chase
Investigation Of The Physical And Electronic Properties Of Indium Doped Zinc Oxide Nanofibers Synthesized By Electrospinning, A. F. Lotus, Y. C. Kang, R. D. Ramsier, George G. Chase
Chemical, Biomolecular, and Corrosion Engineering Faculty Research
Nanostructured metal oxides and particularly nanofiber based materials can provide significant advances for the miniaturization of electronic, optoelectronic, photonic, sensor, and energy conversion devices with enhanced performance based on their unique material properties. In this study, indium doped zinc oxide (IZO) nanofibers were synthesized by electrospinning. These nanofibers have diameters in the range 50-100 nm. The effects of indium addition on the structural, optical, and electrical properties of the zinc oxide nanofiber matrices were investigated. The IZO nanofibers undergo significant changes in their optical and electrical properties compared to undoped zinc oxide nanofibers.
Extremely Active Long-Period Rs Cvn Binary Hd 12545, Bernard W. Bopp, Francis C. Fekel, Jason P. Aufdenberg, Robert C. Dempsey, Virgiljus Dadonas
Extremely Active Long-Period Rs Cvn Binary Hd 12545, Bernard W. Bopp, Francis C. Fekel, Jason P. Aufdenberg, Robert C. Dempsey, Virgiljus Dadonas
Information Systems and Engineering Management Research Publications
The active-chromosphere giant HD 12545 is noteworthy for its remarkable 1990 photmetric amplitude of 0.6 mag in V, which implies that nearly half the visible hemisphere of the star was covered by cool spots. We report the results of a spectroscopic study of HD 12545, showing it to be an active-chromosphere binary with an orbital period of 23.97 days. We establish the spectral type as KO III, and measure v sin i = 17 +/- 2 km/s. The various indicators of activity in the optical and ultraviolet suggest that HD 12545 is one of the most active RS CVn systems …
Uv Observations Of The Cool Dbqa5 White Dwarf Lds 678a - Limits On The Atmospheric Composition, Pressure Shift, And Gravitational Redshift Derived From C I 2479, Terry D. Oswalt, Edward M. Sion, Gordon Hammond, Gerard Vauclair, James W. Liebert, Gary Wegner
Uv Observations Of The Cool Dbqa5 White Dwarf Lds 678a - Limits On The Atmospheric Composition, Pressure Shift, And Gravitational Redshift Derived From C I 2479, Terry D. Oswalt, Edward M. Sion, Gordon Hammond, Gerard Vauclair, James W. Liebert, Gary Wegner
Dartmouth Scholarship
A high-resolution ultraviolet spectrum of the helium-rich degenerate LDS 678A, obtained with the International Ultraviolet Explorer (IUE) satellite, is presented. LDS 678A is the coolest metallic line degenerate (DQ or DZ) yet observed with the IUE echelle. These observations provide a detailed line profile of the strong C I 2479 absorption line and equivalent width W2479 = 2.35 + or - 0.06 A from which theoretical profile fits yield a carbon abundance of log C/He = (-6.7 + or- 0.2). The presence of carbon in a He-rich atmosphere lends credence to the notion that LDS 678A is a transitional case …
Ultraviolet And Optical Spectroscopy Of The R Aquarii Symmetrical Jet, J. M. Hollis, R. J. Oliverson, Menas Kafatos, A. G. Michalitsianos, R. M. Wagner
Ultraviolet And Optical Spectroscopy Of The R Aquarii Symmetrical Jet, J. M. Hollis, R. J. Oliverson, Menas Kafatos, A. G. Michalitsianos, R. M. Wagner
Mathematics, Physics, and Computer Science Faculty Articles and Research
The first ultraviolet spectrum of the southwest (SW) component of the symmetrical jet in the R Aquarii binary system has been obtained in the range 1200-2000 A with the International Ultraviolet Explorer (IUE). These results are compared to more encompassing spectra (1200-3200 A) of the central H II region taken at the same time and also similar spectra of the northeast (NE) jet component obtained 6 months earlier. Moreover, optical spectra of both the NE and SW jet components in the range 3400-9800 A were obtained within ~ 6 months and ~ 1 month, respectively, of the ultraviolet spectra. These …
Sanduleak's Star (Lmc Anonymous): Its Similarity In The Far-Ultraviolet With The Luminous Object N Carinae And Sn 1987a, A. G. Michalitsianos, Menas Kafatos, S. N. Shore
Sanduleak's Star (Lmc Anonymous): Its Similarity In The Far-Ultraviolet With The Luminous Object N Carinae And Sn 1987a, A. G. Michalitsianos, Menas Kafatos, S. N. Shore
Mathematics, Physics, and Computer Science Faculty Articles and Research
Spectra obtained in the far UV wavelength range 1200-2000 A with the International Ultraviolet Explorer (IUE) of the peculiar emission object LMC Anonymous, or Sanduleak's Star in the Large Magellanic Cloud, indicate the presence of circumstellar-high-excitation gas, which is rich in CNO processed material. Although LMC Anonymous is a field star whose nebular line-forming region can not be resolved, and whose mass may be considerably smaller than the massive-luminous galactic object η Carinae, the far-UV spectrum of LMC Anonymous closely resembles that of the S Condensation of η Carinae. The similarity between LMC Anonymous and the S Condensation is apparent …
Chromospherically Active Stars. Iv. Hd 178450=V478 Lyr: An Early-Type By Draconis Type Binary, Francis C. Fekel
Chromospherically Active Stars. Iv. Hd 178450=V478 Lyr: An Early-Type By Draconis Type Binary, Francis C. Fekel
Information Systems and Engineering Management Research Publications
The variable star HD 178450 = V478 Lyr is a chromospherically active G8 V single-lined spectroscopic binary with a period of 2.130514 days. This star has strong ultraviolet emission features and a filled-in Hα absorption line which is variable in strength. It is classified as an early-type BY Draconis system and is similar in many respects to the BY Dra star HD 175742 = V775 Her. The unseen secondary of HD 178450 has a mass of about 0.3 M_sun; and is probably an M2-M3 dwarf. The inclination of the system is 67°±12°. The lithium abundance of the G8 dwarf results …
The C Iv Doublet Ratio Intensity Effect In Symbiotic Stars, A. G. Michalitsianos, Menas Kafatos, R. P. Fahey, R. Viotti, A. Cassatella, A. Altamore
The C Iv Doublet Ratio Intensity Effect In Symbiotic Stars, A. G. Michalitsianos, Menas Kafatos, R. P. Fahey, R. Viotti, A. Cassatella, A. Altamore
Mathematics, Physics, and Computer Science Faculty Articles and Research
The first successful high-resolution ultraviolet spectra in the λλ 1200-2000 wavelength range of the symbiotic variable R Aquarii and its nebular Jet were obtained in 1987 July with the International Ultraviolet Explorer (IUE). The line profile structure of the C IV λλ1548, 1550 doublet in the jet indicates multicomponent velocity structure from an optically thin emitting gas. The C IV doublet profiles in the compact H II region engulfing the Mira and hot companion binary also suggest multicomponent structure, in which the radial velocities range up to ~ -100 km s^- 1. The value of the doublet intensity ratio in …
The Unusual Ultraviolet Variability Of The Qso 3c 232, C. Bruhweilier, Menas Kafatos, U. J. Sofia
The Unusual Ultraviolet Variability Of The Qso 3c 232, C. Bruhweilier, Menas Kafatos, U. J. Sofia
Mathematics, Physics, and Computer Science Faculty Articles and Research
After examining ultraviolet IUE spectra of 18 QSOs with z > 0.35, we find that one object, 3C 232 (z = 0.533), stands out as exhibiting highly unusual spectral and continuum variability. The H 1-Lya shows at least 50% variability on a time scale of roughly a month, while the ultraviolet continuum exhibited approximately a factor of 2 decrease in a day. The magnitude of the UV continuum variability is reminiscent of that seen in the optically violent variables at visual wavelengths. Several spectral features at wavelengths shortward of H I-Lya in the rest frame are identified. A brief discussion COJ?lparing …
Chromospherically Active Stars. I. Hd 136905., Francis C. Fekel, Douglas S. Hall, John L. Africano, Kim Gillies, Robert Quigley, Robert E. Fried
Chromospherically Active Stars. I. Hd 136905., Francis C. Fekel, Douglas S. Hall, John L. Africano, Kim Gillies, Robert Quigley, Robert E. Fried
Information Systems and Engineering Management Research Publications
The variable star HD 136905, recently designated GX Librae, is a chromospherically active K1 III single-lined spectroscopic binary with a period of 11.1345 days. It has moderate strength Ca II H and K and ultraviolet emission features, while Hα is strongly in absorption. The inclination of the systems is 58°±17° and the unseen secondary is most likely a G or K dwarf. The v sin i of the primary, 32±2 km s-1, results in a minimum radius of 7.0±0.4 R_sun;. Since the star fills a substantial fraction of its Roche lobe, the double-peaked light curve seen by photometric observers is …
High Dispersion Untraviolet Spectra Of The Peculiar Star Rx Puppis, Menas Kafatos, A. G. Michalitsianos, R. P. Fahey
High Dispersion Untraviolet Spectra Of The Peculiar Star Rx Puppis, Menas Kafatos, A. G. Michalitsianos, R. P. Fahey
Mathematics, Physics, and Computer Science Faculty Articles and Research
High spectral resolution observations of the peculiar star RX Puppis obtained with the International Ultraviolet Explorer suggest the presence of a complex gaseous ring system which surrounds an accreting hot secondary. The anomalous line intensity ratio of the C IV A.A-1548, 1550 doublet during the observations exceeded the optically thick limit, implying the presence of a high-velocity wind. Additionally, the C IV doublet exhibits about four or five narrow emission components, which are redshifted up to velocities of at least - + 300 km s -I (with respect to the rest wavelength).
Variable Ultraviolet Emission In Sy Muscae, A. G. Michalitsianos, Menas Kafatos
Variable Ultraviolet Emission In Sy Muscae, A. G. Michalitsianos, Menas Kafatos
Mathematics, Physics, and Computer Science Faculty Articles and Research
Following the enhancement in ultraviolet flux which we reported previously, we have continued monitoring the symbiotic variable SY Muscae with the International Ultraviolet Explorer (JUE). Over the course of one year, the prominent emission lines of N v, 0 v, C rv, He II appear to be gradually decreasing in absolute intensity. This appears to coincide with a steady decline in electron density in the emission line forming region, as suggested from the Sim] :\1892 and Cm] :\1909 intensity ratio. Our data is consistent with a sudden ejection event in which material expelled from the surface of a hot Teff …
Observations Of Two Peculiar Emission Objects In The Large Magellanic Cloud, Menas Kafatos, A. G. Michalitsianos, D. A. Allen, R. E. Stencel
Observations Of Two Peculiar Emission Objects In The Large Magellanic Cloud, Menas Kafatos, A. G. Michalitsianos, D. A. Allen, R. E. Stencel
Mathematics, Physics, and Computer Science Faculty Articles and Research
Ultraviolet and visual wavelength spectra were obtained of two peculiar emission objects, Henize S63 and Sanduleak.'s star in the Large Magellanic Cloud. Previously not observed in the near- or far-ultraviolet, both objects exhibit strong permitted and semiforbidden line emission. Estimates based on the absolute continuum flux of the hot companion star in Hen S63 indicate that it rivals the luminosity of the carbon star primary. The emission-line profile structure in both objects does not suggest Wolf-Rayet type emission. Carbon in Sanduleak.'s star (LMC anonymous) is conspicuously absent, while N v, N IV], and N III] dominate the UV emission-line spectrum. …
Ultraviolet Observations Of Four Symbiotic Stars, A. G. Michalitsianos, Menas Kafatos, W. A. Feibelman, R. W. Hobbs
Ultraviolet Observations Of Four Symbiotic Stars, A. G. Michalitsianos, Menas Kafatos, W. A. Feibelman, R. W. Hobbs
Mathematics, Physics, and Computer Science Faculty Articles and Research
Observations were obtained with the International Ultraviolet Explorer (IUE) of four symbiotic stars. The UV spectra of YY Her, SY Mus, CL Sco, and BX Mon are characterized by varying degrees of thermal excitation. We have analyzed these low resolution spectra in terms of line-blanketed model atmospheres of early A, B, and F type stars in order to identify the nature of the hot companion in these systems. The expected emission from early main sequence stars does not fully explain the observed distribution of UV continuum energy over the entire IUE spectral range (1200-3200 A). More likely the observed continuum …
A Brightening Of The Symbiotic Variable Sy Muscae, A. G. Michalitsianos, Menas Kafatos, W. A. Feibelman, G. Wallerstein
A Brightening Of The Symbiotic Variable Sy Muscae, A. G. Michalitsianos, Menas Kafatos, W. A. Feibelman, G. Wallerstein
Mathematics, Physics, and Computer Science Faculty Articles and Research
The symbiotic variable SY Muscae has been observed with IUE in September 1980 and June 1981 and in the photographic region in May 1981. The entire ultraviolet spectrum brightened between September and June by about a factor of 5. The spectrum shows high excitation including emission from N v and high electron density, about 10^10 cm^-3 as determined from various line ratios in the ultraviolet. The optical spectrum is dominated by permitted lines; even [0 m] is very weak again indicating high density in the ionized region. The increase in ultraviolet continuum and line emission may be due to enhanced …
International Ultraviolet Explorer Observations Of The Aquarii Jet, A. G. Michalitsianos, Menas Kafatos
International Ultraviolet Explorer Observations Of The Aquarii Jet, A. G. Michalitsianos, Menas Kafatos
Mathematics, Physics, and Computer Science Faculty Articles and Research
Ultraviolet spectra were obtained with the International Ultraviolet Explorer of the newly discovered optical-radio jet feature in the symbiotic variable R Aquarii. The far-UV continuum of the jet is characterized by strong continuum which rises with decreasing wavelength in the 1200-2000 A wavelength range and is considerably different in appearance from the relatively flat continuum exhibited by ionized nebulosity in the central star. Prominent Si III] and Si II emission lines seen in the central region are virtually absent in the jet. This could reflect the depletion of silicon in the feature, the result of grain formation in material that …
Iue Observations Of The Peculiar Star Rx Puppis, Menas Kafatos, A. G. Michalitsianos, W. A. Feibelman
Iue Observations Of The Peculiar Star Rx Puppis, Menas Kafatos, A. G. Michalitsianos, W. A. Feibelman
Mathematics, Physics, and Computer Science Faculty Articles and Research
We have obtained the first high-dispersion observations of RX Pup in the wavelength region 1200-2000 A with the International Ultraviolet Explorer. RX Pup has been classified a symbiotic star and has been compared to slow novae as well as to 11 Carinae. The anomalies that we observed in high-excitation lines in RX Pup such as He II, 0 III], C III], C IV, and Si IIIl that show split line profiles, Doppler displaced multiple components, and possible inverse P Cygni profiles inN III] and N IV J suggest dynamic activity in circumstellar material that probably has the form of rings …
Ultraviolet Spectrum Of The Crab Nebula, K. Davidson, T. R. Gull, S. P. Maran, T. P. Stecher, R. A. Fesen, R. A. Parise, C. A. Harvel, Menas Kafatos, V. L. Trimble
Ultraviolet Spectrum Of The Crab Nebula, K. Davidson, T. R. Gull, S. P. Maran, T. P. Stecher, R. A. Fesen, R. A. Parise, C. A. Harvel, Menas Kafatos, V. L. Trimble
Mathematics, Physics, and Computer Science Faculty Articles and Research
Data from 65 hours of observation of the Crab Nebula with the International Ultraviolet Explorer are reported, together with new ground-based spectrophotometry. We have measured the important C IV λ1549, He II λ1640, and C III] λ1908 emission line intensities and placed upper limits on other ultraviolet features for the brightest filamentary region in the nebula. We have also measured some ultraviolet continuum surface brightnesses at two places in the Crab. The emission lines imply an average ionic abundance ratio n(C^+2)/n(O^+2 ) in the range from 0.4 to 1.5 in the observed gaseous condensations. The elemental abundance ratio of carbon …
Iue Observations Of A Luminous M Supergiant That Exhibits Emission Continuum In The Far Ultraviolet, A. G. Michalitsianos, Menas Kafatos, R. W. Hobbs
Iue Observations Of A Luminous M Supergiant That Exhibits Emission Continuum In The Far Ultraviolet, A. G. Michalitsianos, Menas Kafatos, R. W. Hobbs
Mathematics, Physics, and Computer Science Faculty Articles and Research
IUE observations of the late-type M supergiant TV Gem (M1 lab) have been obtained that reveal strong UV continuum between 1200 and 3200 A. The continuum is essentially featureless with the exception of a number of broad absorption features in the short wavelength spectral range. UV emission from this star is unexpected because earlier ground-based observations give no indication of a possible association with an early companion or circumstellar ionized nebulosity. We find that a B9 or A1 III-IV type star approximately 2-3 magnitudes fainter than the M star could explain the level of UV continuum observed, but a fully …
Iue Observations Of Rw Hydrae (Gm2 + Pec), Menas Kafatos, A. G. Michalitsianos, R. W. Hobbs
Iue Observations Of Rw Hydrae (Gm2 + Pec), Menas Kafatos, A. G. Michalitsianos, R. W. Hobbs
Mathematics, Physics, and Computer Science Faculty Articles and Research
IUE observations of the late type star RW Hya (gM2 + pec) have been obtained. Analysis of the intense UV continuum observed between 1100 and 2000 A suggests that this object is a binary system in which the secondary is identified as the central star of a planetary nebula with Teff 105 K. The ultraviolet spectrum is characterized by semiforbidden and allowed transition lines, of which the C IV (1548 A, 1550 A) doublet is particularly strong. A general absence of strong forbidden line emission suggests that the compact nebula in which both primary and secondary stars are embedded has …
An Investigation Of A Gas Measurement Technique Employing Ultraviolet Excitation, Alphonso Vincent Diaz
An Investigation Of A Gas Measurement Technique Employing Ultraviolet Excitation, Alphonso Vincent Diaz
Physics Theses & Dissertations
A study was undertaken to determine the general applicability of a temperature measurement technique which uses the fluorescence stimulated by a vacuum ultraviolet continuum as the indicator. This study was directed toward determining the temperature of nonradiating carbon monoxide. A number of ultraviolet radiation sources which produced high intensity in the region of l,150 A were investigated. This study led to the conclusion that the technique was not applicable to measurements in carbon monoxide within the present limits of' detectability.