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• 1. [Article] Effective force constant ratios : iron in iridium and rhodium

  Classical methods of analyzing heat capacity data for the characteristic moments of the frequency distribution are applied to iridium and rhodium. Impurity moments are determined from high and low temperature ...

  Citation × Citation Citation Abstract Copy Title: Effective force constant ratios : iron in iridium and rhodium Author: Munsterman, Dennis Year: 1980 Classical methods of analyzing heat capacity data for the characteristic moments of the frequency distribution are applied to iridium and rhodium. Impurity moments are determined from high and low temperature f values. These moments are combined by modern theory to estimate the magnitude of the host-host to host-impurity force constant ratio. Ratios of the various host moments are also examined. Title: Effective force constant ratios : iron in iridium and rhodium Author: Munsterman, Dennis Year: 1980 Classical methods of analyzing heat capacity data for the characteristic moments of the frequency distribution are applied to iridium and rhodium. Impurity moments are determined from high and low temperature f values. These moments are combined by modern theory to estimate the magnitude of the host-host to host-impurity force constant ratio. Ratios of the various host moments are also examined. Close

• 2. [Article] Controlled Fabrication of High-Yield CdS Nanostructures by Compartment Arrangement

  High-yield, high-purity CdS nanostructures were synthesized in a turf-like configuration using an improved vapor-liquid-solid method. To increase the yield, a compartment arrangement was employed. The ...

  Citation × Citation Citation Abstract Copy Title: Controlled Fabrication of High-Yield CdS Nanostructures by Compartment Arrangement Author: Green, Joshua M., Lawrance, Juno, Jiao, Jun Year: 2008 High-yield, high-purity CdS nanostructures were synthesized in a turf-like configuration using an improved vapor-liquid-solid method. To increase the yield, a compartment arrangement was employed. The specific kind of nanostructure fabricated was found to be directly dependent on the temperature in the compartment. Along with the high-yield growth of CdS nanorods, nanowires, and nanobelts, intertwined structures were also observed, and the electron field emission property of the intertwined structures was investigated and compared with that of other type of nanostructures. Photoluminescence measurements at 10 K showed a peak emission from the CdS nanostructures at 485 nm. Title: Controlled Fabrication of High-Yield CdS Nanostructures by Compartment Arrangement Author: Green, Joshua M., Lawrance, Juno, Jiao, Jun Year: 2008 High-yield, high-purity CdS nanostructures were synthesized in a turf-like configuration using an improved vapor-liquid-solid method. To increase the yield, a compartment arrangement was employed. The specific kind of nanostructure fabricated was found to be directly dependent on the temperature in the compartment. Along with the high-yield growth of CdS nanorods, nanowires, and nanobelts, intertwined structures were also observed, and the electron field emission property of the intertwined structures was investigated and compared with that of other type of nanostructures. Photoluminescence measurements at 10 K showed a peak emission from the CdS nanostructures at 485 nm. Close

• 3. [Article] Environmental Swap Energy and Role of Configurational Entropy in Transfer of Small Molecules from Water into Alkanes

  We studied the effect of segmented solvent molecules on the free energy of transfer of small molecules from water into alkanes (hexane, heptane, octane, decane, dodecane, tetradecane, and hexadecane). ...

  Citation × Citation Citation Abstract Copy Title: Environmental Swap Energy and Role of Configurational Entropy in Transfer of Small Molecules from Water into Alkanes Author: Smejtek, Pavel, Word, Robert Campbell Year: 2004 We studied the effect of segmented solvent molecules on the free energy of transfer of small molecules from water into alkanes (hexane, heptane, octane, decane, dodecane, tetradecane, and hexadecane). For these alkanes we measured partition coefficients of benzene, 3-methylindole (3MI), 2,3,4,6-tetrachlorophenol (TeCP), and 2,4,6-tribromophenol (TriBP) at 3, 11, 20, 3, and 47 °C. For 3MI, TeCP, and TriBP the dependence of free energy of transfer on length of alkane chains was found to be very different from that for benzene. In contrast to benzene, the energy of transfer for 3MI, TeCP, and TriBP was independent of the number of carbons in alkanes. To interpret data, we used the classic Flory–Huggins (FH) theory of concentrated polymer solutions for the alkane phase. For benzene, the measured dependence of energy of transfer on the number of carbons in alkanes agreed well with predictions based on FH model in which the size of alkane segments was obtained from the ratio of molar volumes of alkanes and the solute. We show that for benzene, the energy of transfer can be divided into two components, one called environmental swap energy (ESE), and one representing the contribution of configurational entropy of alkane chains. For 3MI, TeCP, and TriBP the contribution of configurational entropy was not measurable even though the magnitude of the effect predicted from the FH model for short chain alkanes was as much as 20 times greater than experimental uncertainties. From the temperature dependence of ESE we obtained enthalpy and entropy of transfer for benzene, 3MI, TeCP, and TriBP. Experimental results are discussed in terms of a thermodynamic cycle considering creation of cavity, insertion of solute, and activation of solute-medium attractive interactions. Our results suggest that correcting experimental free energy of transfer by Flory–Huggins configurational entropy term is not generally appropriate and cannot be applied indiscriminately. An Erratum has been published and is located here: http://archives.pdx.edu/ds/psu/8365 Title: Environmental Swap Energy and Role of Configurational Entropy in Transfer of Small Molecules from Water into Alkanes Author: Smejtek, Pavel, Word, Robert Campbell Year: 2004 We studied the effect of segmented solvent molecules on the free energy of transfer of small molecules from water into alkanes (hexane, heptane, octane, decane, dodecane, tetradecane, and hexadecane). For these alkanes we measured partition coefficients of benzene, 3-methylindole (3MI), 2,3,4,6-tetrachlorophenol (TeCP), and 2,4,6-tribromophenol (TriBP) at 3, 11, 20, 3, and 47 °C. For 3MI, TeCP, and TriBP the dependence of free energy of transfer on length of alkane chains was found to be very different from that for benzene. In contrast to benzene, the energy of transfer for 3MI, TeCP, and TriBP was independent of the number of carbons in alkanes. To interpret data, we used the classic Flory–Huggins (FH) theory of concentrated polymer solutions for the alkane phase. For benzene, the measured dependence of energy of transfer on the number of carbons in alkanes agreed well with predictions based on FH model in which the size of alkane segments was obtained from the ratio of molar volumes of alkanes and the solute. We show that for benzene, the energy of transfer can be divided into two components, one called environmental swap energy (ESE), and one representing the contribution of configurational entropy of alkane chains. For 3MI, TeCP, and TriBP the contribution of configurational entropy was not measurable even though the magnitude of the effect predicted from the FH model for short chain alkanes was as much as 20 times greater than experimental uncertainties. From the temperature dependence of ESE we obtained enthalpy and entropy of transfer for benzene, 3MI, TeCP, and TriBP. Experimental results are discussed in terms of a thermodynamic cycle considering creation of cavity, insertion of solute, and activation of solute-medium attractive interactions. Our results suggest that correcting experimental free energy of transfer by Flory–Huggins configurational entropy term is not generally appropriate and cannot be applied indiscriminately. An Erratum has been published and is located here: http://archives.pdx.edu/ds/psu/8365 Close

• 4. [Article] Indirect-Drive Noncryogenic Double-Shell Ignition Targets for the National Ignition Facility: Design and Analysis

  Analysis and design of indirect-drive National Ignition Facility double-shell targets with hohlraum temperatures of 200 eV and 250 eV are presented. The analysis of these targets includes the assessment ...

  Citation × Citation Citation Abstract Copy Title: Indirect-Drive Noncryogenic Double-Shell Ignition Targets for the National Ignition Facility: Design and Analysis Author: Amendt, Peter A., Colvin, J. D., Tipton, R. E., Hinkel, D. E., Edwards, M. J., Landen, O. L., Ramshaw, John D., Suter, L. J., Varnum, W. S., Watt, R. G. Year: 2002 Analysis and design of indirect-drive National Ignition Facility double-shell targets with hohlraum temperatures of 200 eV and 250 eV are presented. The analysis of these targets includes the assessment of two-dimensional radiation asymmetry and nonlinear mix. Two-dimensional integrated hohlraum simulations indicate that the x-ray illumination can be adjusted to provide adequate symmetry control in hohlraums specially designed to have high laser-coupling efficiency [Suter et al., Phys. Plasmas 7, 2092 (2000)]. These simulations also reveal the need to diagnose and control localized 10?15 keV x-ray emission from the high-Z hohlraum wall because of strong absorption by the high-Z inner shell. Preliminary estimates of the degree of laser backscatter from an assortment of laser?plasma interactions suggest comparatively benign hohlraum conditions. The application of a variety of nonlinear mix models and phenomenological tools, including buoyancy-drag models, multimode simulations and fall-line optimization, indicates a possibility of achieving ignition, i.e., fusion yields greater than 1 MJ. Planned experiments on the Omega laser will test current understanding of high-energy radiation flux asymmetry and mix-induced yield degradation in double-shell targets. Title: Indirect-Drive Noncryogenic Double-Shell Ignition Targets for the National Ignition Facility: Design and Analysis Author: Amendt, Peter A., Colvin, J. D., Tipton, R. E., Hinkel, D. E., Edwards, M. J., Landen, O. L., Ramshaw, John D., Suter, L. J., Varnum, W. S., Watt, R. G. Year: 2002 Analysis and design of indirect-drive National Ignition Facility double-shell targets with hohlraum temperatures of 200 eV and 250 eV are presented. The analysis of these targets includes the assessment of two-dimensional radiation asymmetry and nonlinear mix. Two-dimensional integrated hohlraum simulations indicate that the x-ray illumination can be adjusted to provide adequate symmetry control in hohlraums specially designed to have high laser-coupling efficiency [Suter et al., Phys. Plasmas 7, 2092 (2000)]. These simulations also reveal the need to diagnose and control localized 10?15 keV x-ray emission from the high-Z hohlraum wall because of strong absorption by the high-Z inner shell. Preliminary estimates of the degree of laser backscatter from an assortment of laser?plasma interactions suggest comparatively benign hohlraum conditions. The application of a variety of nonlinear mix models and phenomenological tools, including buoyancy-drag models, multimode simulations and fall-line optimization, indicates a possibility of achieving ignition, i.e., fusion yields greater than 1 MJ. Planned experiments on the Omega laser will test current understanding of high-energy radiation flux asymmetry and mix-induced yield degradation in double-shell targets. Close

• 5. [Article] Study of the numerical modeling of the temperature dependence of the dark current in Charge Coupled Devices

  As it is well known, the classical works of the Dark Current Spectroscopy method allow - using some not too accurate theoretical relations, but huge numbers of dark current values for thousands of pixels ...

  Citation × Citation Citation Abstract Copy Title: Study of the numerical modeling of the temperature dependence of the dark current in Charge Coupled Devices Author: Widenhorn, Ralf, Tunaru, Ionel, Bodegom, Erik, Iordache, Dan A. Year: 2010 As it is well known, the classical works of the Dark Current Spectroscopy method allow - using some not too accurate theoretical relations, but huge numbers of dark current values for thousands of pixels - the evaluation of a reduced number of basic impurities parameters. Unlike these works, this paper tries to obtain--by means of some better approximations of the Shockley-Read-Hall (SRH) model--more information about the studied impurities, as well as the study of the compatibility of the used theoretical model SRH relative to the experimental data. In this manner, both the compatibility SRH model with the studied experimental data was checked up, as well as the values of some additional physical parameters of the impurified semiconductor (the logarithms of the pre-exponential factors lnDiff, lnDep, the effective value of the energy gap Eg) and of the separate capture cross-sections of the free electrons, and holes, respectively, by the studied deep-level contaminants, were evaluated. Title: Study of the numerical modeling of the temperature dependence of the dark current in Charge Coupled Devices Author: Widenhorn, Ralf, Tunaru, Ionel, Bodegom, Erik, Iordache, Dan A. Year: 2010 As it is well known, the classical works of the Dark Current Spectroscopy method allow - using some not too accurate theoretical relations, but huge numbers of dark current values for thousands of pixels - the evaluation of a reduced number of basic impurities parameters. Unlike these works, this paper tries to obtain--by means of some better approximations of the Shockley-Read-Hall (SRH) model--more information about the studied impurities, as well as the study of the compatibility of the used theoretical model SRH relative to the experimental data. In this manner, both the compatibility SRH model with the studied experimental data was checked up, as well as the values of some additional physical parameters of the impurified semiconductor (the logarithms of the pre-exponential factors lnDiff, lnDep, the effective value of the energy gap Eg) and of the separate capture cross-sections of the free electrons, and holes, respectively, by the studied deep-level contaminants, were evaluated. Close

• 6. [Article] Interpreting Activation Energies in Digital Image Sensors

  We present a study demonstrating the dependence of apparent activation energies on signal charge in digital image sensors. The data presented in this paper are for a charge-coupled device imager, but the ...

  Citation × Citation Citation Abstract Copy Title: Interpreting Activation Energies in Digital Image Sensors Author: Dunlap, Justin C., Blouke, Morley M., Bodegom, Erik, Widenhorn, Ralf Year: 2015 We present a study demonstrating the dependence of apparent activation energies on signal charge in digital image sensors. The data presented in this paper are for a charge-coupled device imager, but the analysis can be applied to CMOS sensors or generally to any system that shows nonlinearity with respect to time. Activation energies for some pixels are observed to vary between values at about half the bandgap of silicon, when calculated at low signal-charge levels, to values approaching the bandgap when calculated at high signal-charge levels. As such, the traditional method of calculating activation energies using a single exposure time at varying temperatures will result in different activation energies dependent on the exposure time chosen, making it difficult to draw physically meaningful conclusions from its value. Therefore, a method of calculating activation energies using a single signal-charge level is proposed, making it easier to correlate activation energies with impurities. Further, we demonstrate how a model of a pixel with a fixed location impurity in conjunction with a moving depletion edge, due to a changing depletion region size, can lead to this behavior. Title: Interpreting Activation Energies in Digital Image Sensors Author: Dunlap, Justin C., Blouke, Morley M., Bodegom, Erik, Widenhorn, Ralf Year: 2015 We present a study demonstrating the dependence of apparent activation energies on signal charge in digital image sensors. The data presented in this paper are for a charge-coupled device imager, but the analysis can be applied to CMOS sensors or generally to any system that shows nonlinearity with respect to time. Activation energies for some pixels are observed to vary between values at about half the bandgap of silicon, when calculated at low signal-charge levels, to values approaching the bandgap when calculated at high signal-charge levels. As such, the traditional method of calculating activation energies using a single exposure time at varying temperatures will result in different activation energies dependent on the exposure time chosen, making it difficult to draw physically meaningful conclusions from its value. Therefore, a method of calculating activation energies using a single signal-charge level is proposed, making it easier to correlate activation energies with impurities. Further, we demonstrate how a model of a pixel with a fixed location impurity in conjunction with a moving depletion edge, due to a changing depletion region size, can lead to this behavior. Close

• 7. [Article] Laser as a Tool to Study Radiation Effects in CMOS

  Energetic particles from cosmic ray or terrestrial sources can strike sensitive areas of CMOS devices and cause soft errors. Understanding the effects of such interactions is crucial as the device technology ...

  Citation × Citation Citation Abstract Copy Title: Laser as a Tool to Study Radiation Effects in CMOS Author: Ajdari, Bahar Year: 2017 Energetic particles from cosmic ray or terrestrial sources can strike sensitive areas of CMOS devices and cause soft errors. Understanding the effects of such interactions is crucial as the device technology advances, and chip reliability has become more important than ever. Particle accelerator testing has been the standard method to characterize the sensitivity of chips to single event upsets (SEUs). However, because of their costs and availability limitations, other techniques have been explored. Pulsed laser has been a successful tool for characterization of SEU behavior, but to this day, laser has not been recognized as a comparable method to beam testing. In this thesis, I propose a methodology of correlating laser soft error rate (SER) to particle beam gathered data. Additionally, results are presented showing a temperature dependence of SER and the "neighbor effect" phenomenon where due to the close proximity of devices a "weakening effect" in the ON state can be observed. Title: Laser as a Tool to Study Radiation Effects in CMOS Author: Ajdari, Bahar Year: 2017 Energetic particles from cosmic ray or terrestrial sources can strike sensitive areas of CMOS devices and cause soft errors. Understanding the effects of such interactions is crucial as the device technology advances, and chip reliability has become more important than ever. Particle accelerator testing has been the standard method to characterize the sensitivity of chips to single event upsets (SEUs). However, because of their costs and availability limitations, other techniques have been explored. Pulsed laser has been a successful tool for characterization of SEU behavior, but to this day, laser has not been recognized as a comparable method to beam testing. In this thesis, I propose a methodology of correlating laser soft error rate (SER) to particle beam gathered data. Additionally, results are presented showing a temperature dependence of SER and the "neighbor effect" phenomenon where due to the close proximity of devices a "weakening effect" in the ON state can be observed. Close

• 8. [Article] Aqueous Red-Emitting Silicon Nanoparticles for Cellular Imaging: Consequences of Protecting Against Surface Passivation by Hydroxide and Water for Stable Red Emission

  Stable, aqueous, red-to-near infrared emission is critical for the use of silicon nanoparticles (Si NPs) in biological fluorescence assays, but such Si NPs have been difficult to attain. We report a synthesis ...

  Citation × Citation Citation Abstract Copy Title: Aqueous Red-Emitting Silicon Nanoparticles for Cellular Imaging: Consequences of Protecting Against Surface Passivation by Hydroxide and Water for Stable Red Emission Author: Chiu, Sheng-Kuei, Manhat, Beth Ann, DeBenedetti, William J.I., Brown, Anna L., Fichter, Katye, Vu, Tania, Eastman, Micah, Jiao, Jun, Goforth, Andrea Mitchell Year: 2013 Stable, aqueous, red-to-near infrared emission is critical for the use of silicon nanoparticles (Si NPs) in biological fluorescence assays, but such Si NPs have been difficult to attain. We report a synthesis and surface modification strategy that protects Si NPs and preserves red photoluminescence (PL) in water for more than 6 mo. The Si NPs were synthesized via high temperature reaction, liberated from an oxide matrix, and functionalized via hydrosilylation to yield hydrophobic particles. The hydrophobic Si NPs were phase transferred to water using the surfactant cetyltrimethylammonium bromide (CTAB) with retention of red PL. CTAB apparently serves a double role in providing stable, aqueous, red-emitting Si NPs by (i) forming a hydrophobic barrier between the Si NPs and water and (ii) providing aqueous colloidal stability via the polar head group. We demonstrate preservation of the aqueous red emission of these Si NPs in biological media and examine the effects of pH on emission color. Title: Aqueous Red-Emitting Silicon Nanoparticles for Cellular Imaging: Consequences of Protecting Against Surface Passivation by Hydroxide and Water for Stable Red Emission Author: Chiu, Sheng-Kuei, Manhat, Beth Ann, DeBenedetti, William J.I., Brown, Anna L., Fichter, Katye, Vu, Tania, Eastman, Micah, Jiao, Jun, Goforth, Andrea Mitchell Year: 2013 Stable, aqueous, red-to-near infrared emission is critical for the use of silicon nanoparticles (Si NPs) in biological fluorescence assays, but such Si NPs have been difficult to attain. We report a synthesis and surface modification strategy that protects Si NPs and preserves red photoluminescence (PL) in water for more than 6 mo. The Si NPs were synthesized via high temperature reaction, liberated from an oxide matrix, and functionalized via hydrosilylation to yield hydrophobic particles. The hydrophobic Si NPs were phase transferred to water using the surfactant cetyltrimethylammonium bromide (CTAB) with retention of red PL. CTAB apparently serves a double role in providing stable, aqueous, red-emitting Si NPs by (i) forming a hydrophobic barrier between the Si NPs and water and (ii) providing aqueous colloidal stability via the polar head group. We demonstrate preservation of the aqueous red emission of these Si NPs in biological media and examine the effects of pH on emission color. Close

• 9. [Article] Existence of High-Order Superlattices in Orientationally Ordered C_{60}

  We correlate the presence or absence of high-order modulated structures in solid C60 with the differential scanning calorimetry signature of the orientational ordering transition and other diagnostic data. ...

  Citation × Citation Citation Abstract Copy Title: Existence of High-Order Superlattices in Orientationally Ordered C_{60} Author: Fischer, J. E., Luzzi, D. E., Kniaź, K., McGhie, A. R., Ricketts-Foot, D. A., Romanow, W. R., Vaughan, Gavin B. M., Li, Dayin, Smith, Allan L., Strongin, Robert M., Cichy, M. A., Bard, Laurent, Smith, Amos B., III Year: 1993 We correlate the presence or absence of high-order modulated structures in solid C60 with the differential scanning calorimetry signature of the orientational ordering transition and other diagnostic data. We have searched for, but not observed, the 2a face-centered cubic structure recently observed in low-temperature electron and single-crystal x-ray diffraction. We conclude that the intrinsic ground state is the previously reported simple cubic structure [space groupPa3¯, a(14 K)=14.06 Å], and that other structures may be stabilized by defects or impurities. Title: Existence of High-Order Superlattices in Orientationally Ordered C_{60} Author: Fischer, J. E., Luzzi, D. E., Kniaź, K., McGhie, A. R., Ricketts-Foot, D. A., Romanow, W. R., Vaughan, Gavin B. M., Li, Dayin, Smith, Allan L., Strongin, Robert M., Cichy, M. A., Bard, Laurent, Smith, Amos B., III Year: 1993 We correlate the presence or absence of high-order modulated structures in solid C60 with the differential scanning calorimetry signature of the orientational ordering transition and other diagnostic data. We have searched for, but not observed, the 2a face-centered cubic structure recently observed in low-temperature electron and single-crystal x-ray diffraction. We conclude that the intrinsic ground state is the previously reported simple cubic structure [space groupPa3¯, a(14 K)=14.06 Å], and that other structures may be stabilized by defects or impurities. Close

• 10. [Article] Unusual Thermal Stability of a Site-Ordered MC60 Rocksalt Structure (M=K, Rb, or Cs).

  X-ray diffraction and differential scanning calorimetry of MxC60, with x∼1 and M=K, Rb, or Cs, reveal an unusual T-dependent phase sequence. A low-symmetry ground state is found, while the high-T limit ...

  Citation × Citation Citation Abstract Copy Title: Unusual Thermal Stability of a Site-Ordered MC60 Rocksalt Structure (M=K, Rb, or Cs). Author: Zhu, Q., Zhou, O., Fischer, J. E., McGhie, Andrew R., Romanow, W. R., Strongin, Robert M., Cichy, M. A., Smith, Amos B., III Year: 1993 X-ray diffraction and differential scanning calorimetry of MxC60, with x∼1 and M=K, Rb, or Cs, reveal an unusual T-dependent phase sequence. A low-symmetry ground state is found, while the high-T limit is an ordered rocksalt structure in which only the octahedral sites are occupied. The unusual high-T stability of this ordered phase is attributed to the entropy of molecular orientational disorder and/or thermal disorder of the alkali-metal ions within the octahedral sites. Unique to KxC60 with x≥1.4, we find at intermediate temperatures an fcc site-disordered lattice gas phase with random occupancy of tetrahedral and octahedral sites, which is thus isostructural with superconducting K3C60. Title: Unusual Thermal Stability of a Site-Ordered MC60 Rocksalt Structure (M=K, Rb, or Cs). Author: Zhu, Q., Zhou, O., Fischer, J. E., McGhie, Andrew R., Romanow, W. R., Strongin, Robert M., Cichy, M. A., Smith, Amos B., III Year: 1993 X-ray diffraction and differential scanning calorimetry of MxC60, with x∼1 and M=K, Rb, or Cs, reveal an unusual T-dependent phase sequence. A low-symmetry ground state is found, while the high-T limit is an ordered rocksalt structure in which only the octahedral sites are occupied. The unusual high-T stability of this ordered phase is attributed to the entropy of molecular orientational disorder and/or thermal disorder of the alkali-metal ions within the octahedral sites. Unique to KxC60 with x≥1.4, we find at intermediate temperatures an fcc site-disordered lattice gas phase with random occupancy of tetrahedral and octahedral sites, which is thus isostructural with superconducting K3C60. Close