Relevant bibliographies by topics / Large Carbon Cluster Thin Films

Academic literature on the topic 'Large Carbon Cluster Thin Films'

Author: Grafiati
Published: 6 September 2023

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Contents

Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Large Carbon Cluster Thin Films.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Journal articles on the topic "Large Carbon Cluster Thin Films"

1

Shinde, Deodatta, Stefan Fritze, Mattias Thuvander, Paulius Malinovskis, Lars Riekehr, Ulf Jansson, and Krystyna Stiller. "Elemental Distribution in CrNbTaTiW-C High Entropy Alloy Thin Films." Microscopy and Microanalysis 25, no. 2 (February 4, 2019): 489–500. http://dx.doi.org/10.1017/s1431927618016264.

Full text
Abstract:
AbstractThe microstructure and distribution of the elements have been studied in thin films of a near-equimolar CrNbTaTiW high entropy alloy (HEA) and films with 8 at.% carbon added to the alloy. The films were deposited by magnetron sputtering at 300°C. X-ray diffraction shows that the near-equimolar metallic film crystallizes in a single-phase body centered cubic (bcc) structure with a strong (110) texture. However, more detailed analyses with transmission electron microscopy (TEM) and atom probe tomography (APT) show a strong segregation of Ti to the grain boundaries forming a very thin Ti–Cr rich interfacial layer. The effect can be explained by the large negative formation enthalpy of Ti–Cr compounds and shows that CrNbTaTiW is not a true HEA at lower temperatures. The addition of 8 at.% carbon leads to the formation of an amorphous structure, which can be explained by the limited solubility of carbon in bcc alloys. TEM energy-dispersive X-ray spectroscopy indicated that all metallic elements are randomly distributed in the film. The APT investigation, however, revealed that carbide-like clusters are present in the amorphous film.
APA, Harvard, Vancouver, ISO, and other styles
2

Babonneau, D., A. Naudon, D. Thiaudière, and S. Lequien. "Morphological characterization of ion-sputtered C–Ag, C/C–Ag and Ag/C films by GISAXS." Journal of Applied Crystallography 32, no. 2 (April 1, 1999): 226–33. http://dx.doi.org/10.1107/s0021889898011996.

Full text
Abstract:
A carbon–silver thin film (33 at.% Ag and thickness of 2100 Å) has been synthesized by co-sputtering of a C–Ag target and characterized by grazing-incidence small-angle X-ray scattering (GISAXS), a technique that gives a considerably enhanced surface sensitivity. Experiments have been carried out at or near the critical angle of the layer. It is shown that, because C and Ag show no mutual solubility, a demixing occurs during the co-deposition process and silver clusters form within an amorphous carbon matrix. Using different incident angles of the X-ray beam, it is demonstrated that two populations of clusters are present in the layer: some large and nearly spherical on the surface, others smaller and elongated along the direction of the growth of the thin film in the bulk. In the case of a C/C–Ag bilayer, the surface diffusion is avoided just after the co-deposition process and it is shown that only the small and elongated clusters in the bulk are formed. In the case of a very thin Ag/C layer, there is only surface diffusion and it is shown that large silver islands are formed on the carbon surface. Such experiments demonstrate that the growth mechanism that takes place during the co-deposition process involves mainly a surface diffusion of silver and carbon atoms, as opposed to a volume diffusion.
APA, Harvard, Vancouver, ISO, and other styles
3

Watanabe, Yoshihisa, Yoshikazu Nakamura, Shigekazu Hirayama, and Yoshimasa Yamaguchi. "Thermally stimulated exoelectron emission from hydrogenated amorphous carbon films." Journal of Materials Research 7, no. 7 (July 1992): 1805–8. http://dx.doi.org/10.1557/jmr.1992.1805.

Full text
Abstract:
Hydrogenated amorphous carbon (a–C:H) films on stainless steel (AISI430) substrate oxidized in air at 1273 K were prepared from a gas mixture of methane and hydrogen by an rf plasma chemical vapor deposition, and thermally stimulated exoelectron emission (TSEE) was studied for the x-ray irradiated a–C:H films. Glow curves and energy distributions of TSEE from the 80- and 280-nm a–C:H films and from the AISI430 substrate have been measured under ultrahigh vacuum conditions. It was found that the glow curve from the 80-nm a–C:H film was similar to that from the AISI430 substrate, but it was quite different from that from the 280-nm film; the values of the mean energy of exoelectrons at the glow peak temperatures from the 80-nm a–C:H film are almost the same as those from the substrate but are much lower than those of the 280-nm film. The surfaces of 80- and 280-nm a–C:H films are observed with the scanning electron microscope (SEM). Observations by SEM show that the 80-nm film has relatively large-sized clusters of films and the stainless steel substrate still appears in some places, but the surface of the 280-nm film is completely covered by the carbon films. From these results, we propose that TSEE from the 80-nm film originates mainly from the oxide films on the stainless steel substrate and TSEE from the 280-nm film originates from the film itself. Thus, TSEE can be applied to characterize the surface of thin films.
APA, Harvard, Vancouver, ISO, and other styles
4

Alekseeva, Olga, Artem Mikhalev, Elena Lutikova, Vladimir Porembsky, Mikhail Presnyakov, Vladimir Fateev, Boris Shapir, and Sergey Grigoriev. "Structural and Electrocatalytic Properties of Platinum and Platinum-Carbon Layers Obtained by Magnetron-Ion Sputtering." Catalysts 8, no. 12 (December 18, 2018): 665. http://dx.doi.org/10.3390/catal8120665.

Full text
Abstract:
This article is devoted to further development of magnetron sputtering technology for catalysts and catalysts layer production for fuel cells and other electrochemical devices. Platinum-carbon films with Pt content up to 95–97 wt % were deposited using different sputtering regimes—DC (direct current) sputtering with and without application of a pulse negative bias voltage to the titanium substrate and also bipolar pulse sputtering with frequency of 10 kHz and 100 kHz. Composite platinum carbon targets were used for sputtering. Characteristics of platinum-carbon films were compared with those of platinum films deposited using the same regimes. The main methods of investigation were scanning transmission electron microscopy (STEM) with energy dispersive X-ray spectroscopy; potentiostatic and potentiodynamic methods. The catalytic activity of platinum-carbon films increased with platinum content and at a platinum concentration of 95–97 wt % became higher than that of platinum films sputtered in the same regimes. It was proposed that carbon atoms deposited on the substrate limited the mobility of the deposited platinum species and inhibited Pt cluster growth. Platinum-carbon films produced by pulsed DC magnetron sputtering with pulsed frequency 100 kHz consisted of narrow Pt columns with dome nanotops forming a well-developed surface. The porosity and specific surface of these columnar nanopillar films were higher compared with those of pure platinum films deposited under the same conditions. Moreover, the platinum-carbon films deposited using a bipolar pulse regime with a frequency of 100 kHz had the highest specific surface, porosity (30%) and catalytic activity in hydrogen and oxygen evolution due to a high ion current density and reduced pulse duration which inhibited the growth of large platinum globules.
APA, Harvard, Vancouver, ISO, and other styles
5

Fonseca, Alexandre F., Tao Liang, Difan Zhang, Kamal Choudhary, Simon R. Phillpot, and Susan B. Sinnott. "Titanium-Carbide Formation at Defective Curved Graphene-Titanium Interfaces." MRS Advances 3, no. 8-9 (2018): 457–62. http://dx.doi.org/10.1557/adv.2018.115.

Full text
Abstract:
ABSTRACTPhysical and chemical properties of graphene-metal interfaces have been largely examined with the objective of producing nanostructured carbon-based electronic devices. Although electronic properties are key to such devices, appropriate structural, thermal and mechanical properties are important for device performance as well. One of the most studied is the graphene-titanium (G-Ti) interface. Titanium is a low density, high strength versatile metal that can form alloys with desirable properties for applications ranging from aerospace to medicine. Small clusters and thin films of titanium deposited on graphene have also been examined. However, while some experiments show that thin films of titanium on graphene can be removed without damaging graphene hexagonal structure, others reported the formation of titanium-carbide (TiC) at G-Ti interfaces. In a previous work [ACS Appl. Mater. Interfaces, 2017, 9 (38), pp 33288-33297], we have shown that pristine G-Ti interfaces are resilient to large thermal fluctuations even when G-Ti structures lie on curved or kinked substrates. Here, using classical molecular dynamics with the third-generation Charge Optimized Many Body (COMB3) potential, we show that di-interstitial defective G-Ti structures on a copper substrate with a relatively large curvature kink, present signs of TiC formation. This result might help explain the different experimental results mentioned above.
APA, Harvard, Vancouver, ISO, and other styles
6

Milani, P., M. Ferretti, P. Piseri, C. E. Bottani, A. Ferrari, A. Li Bassi, G. Guizzetti, and M. Patrini. "Synthesis and characterization of cluster-assembled carbon thin films." Journal of Applied Physics 82, no. 11 (December 1997): 5793–98. http://dx.doi.org/10.1063/1.366446.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Buzio, R., E. Gnecco, C. Boragno, U. Valbusa, P. Piseri, E. Barborini, and P. Milani. "Self-affine properties of cluster-assembled carbon thin films." Surface Science 444, no. 1-3 (January 2000): L1—L6. http://dx.doi.org/10.1016/s0039-6028(99)01066-3.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Ferrari, A. C., B. S. Satyanarayana, J. Robertson, W. I. Milne, E. Barborini, P. Piseri, and P. Milani. "Electron field emission from cluster-assembled carbon thin films." Europhysics Letters (EPL) 46, no. 2 (April 15, 1999): 245–50. http://dx.doi.org/10.1209/epl/i1999-00251-7.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

MÉLINON, P., V. PAILLARD, V. DUPUIS, J. P. PEREZ, J. TUAILLON, A. PEREZ, B. BARBARA, L. THOMAS, and M. BOUDEULLE. "CORRELATION BETWEEN FREE-CLUSTER PROPERTIES AND THIN FILMS ELABORATED BY LOW-ENERGY CLUSTER-BEAM DEPOSITION." Surface Review and Letters 03, no. 01 (February 1996): 1007–11. http://dx.doi.org/10.1142/s0218625x96001807.

Full text
Abstract:
The properties of thin films obtained by low-energy cluster-beam deposition are reviewed. The main characteristics are the nanoscale granular structure and the memory effect of the free-cluster properties. The first point is evidenced by the specific magnetic properties of transition-metal films, which are intermediate between amorphous and bulk phases, while the second point is illustrated from carbon films exhibiting the electronic structure of the free carbon cluster.
APA, Harvard, Vancouver, ISO, and other styles
10

Piseri, P., E. Barborini, M. Marino, P. Milani, C. Lenardi, L. Zoppi, and L. Colombo. "Hydrogen Uptake in Cluster-Assembled Carbon Thin Films: Experiment and Computer Simulation." Journal of Physical Chemistry B 108, no. 17 (April 2004): 5157–60. http://dx.doi.org/10.1021/jp037146f.

Full text
APA, Harvard, Vancouver, ISO, and other styles
More sources

Dissertations / Theses on the topic "Large Carbon Cluster Thin Films"

1

Bettini, L. G. "Synthesis and electrochemical investigation of cluster assembled carbon thin films." Doctoral thesis, Università degli Studi di Milano, 2013. http://hdl.handle.net/2434/217165.

Full text
Abstract:
Nanostructured materials grown by the deposition of clusters with low kinetic energy are unique systems that preserve the original size dependent features of their building blocks. As porous materials with high surface to volume ratio they have a tremendous technological potential toward the development of green, cheap and efficient energy storage and harvesting systems, including carbon based supercapacitors. This thesis is devoted to the synthesis and electrochemical investigation of nanostructured carbon (ns-C) thin films and composites grown by the Supersonic Cluster Beam Deposition (SCBD) of clusters formed in a Pulsed Microplasma Cluster Source (PMCS). The electrochemical properties of cluster assembled thin films are assessed by the study of the electric double layer (EDL) formed at the interface between ns-C based electrodes and a liquid electrolyte. Ns-C behavior as electrode material has been characterized as function of thickness, post deposition thermal treatment, metal nanoparticles embedding and electrolyte type. This study is carried out by means of atomic force microscopy (AFM), Raman spectroscopy, x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and electrochemical techniques, such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Our results establish the feasibility of the SCBD technique for the synthesis of nanostructured carbon and metal:carbon nanocomposite thin films with promising potential as porous material for thin film electrochemical energy storage.
APA, Harvard, Vancouver, ISO, and other styles
2

Yao, Shulong. "Highly Stretchable Miniature Strain Sensor for Large Dynamic Strain Measurement." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc849674/.

Full text
Abstract:
This thesis aims to develop a new type of highly stretchable strain sensor to measure large deformation of a specimen subjected to dynamic loading. The sensor was based on the piezo-resistive response of carbon nanotube(CNT)/polydimethysiloxane (PDMS) composites thin films, some nickel particles were added into the sensor composite to improve the sensor performance. The piezo-resistive response of CNT composite gives high frequency response in strain measurement, while the ultra-soft PDMS matrix provides high flexibility and ductility for large strain measuring large strain (up to 26%) with an excellent linearity and a fast frequency response under quasi-static test, the delay time for high strain rate test is just 30 μs. This stretchable strain sensor is also able to exhibit much higher sensitivities, with a gauge factor of as high as 80, than conventional foil strain gauges.
APA, Harvard, Vancouver, ISO, and other styles
3

Srinath, S. "Development of Novel Heat Transfer Gauges Based on Large Carbon Clusters to Measure Total as well as Radiative Heat Flux for Planetary Entry Configurations in Hypersonic Shock Tunnels." Thesis, 2017. http://etd.iisc.ac.in/handle/2005/4243.

Full text
Abstract:
The quest of travelling beyond earth, preludes with ground based experimental studies, detailed analysis and accurate calculations in the aspects of having a safer design of flying vehicles. As the vehicles plunge into the dense atmosphere with greater velocities to hypersonic Mach numbers, the shockwave produced ahead of the aerodynamic body becomes highly intense producing volatile conditions at a temperature of several thousands of Kelvins. Predominantly the unsteady effects are dominated by radiations in the velocities which are greater than 6km/s. During such high enthalpy flows, the atmospheric molecules which cross the strong shockwave are excited to higher energy states. Therefore the shocked gas ahead of the space vehicle is at a state of chemical and thermal non-equilibrium. To attain equilibrium condition, energy is released from high enthalpy fluid to surroundings. The aerodynamic body which faces this energy release is heated by all modes of heat transfer. Behind the normal shock, excited molecules relax to lower levels by energy releasing mechanisms including emission of radiation. In this process, initial photons emitted are absorbed by other molecules further raising its energy levels leading to dissociation and ionization. During recombination of molecular species more photons are released. Such radiations from molecules and shock wave reach the surface of the aerodynamic body. Collective absorption of all incident radiation heats up the surface of planetary entry body. In particular, the radiative heating predominates at very high velocities. Direct measurement of total radiative heating is highly challenging due to the complexity in finding out a proper measurement device. Existing literatures show that only a partial amount of radiative heating could be measured by thin film gauges, since the efficiency of thin film based measurement technique depends on the absorption of sensing element used and the wavelength range of the radiation. In the present work, it is attempted to measure the radiative heat flux over aerodynamic body in the hypersonic flow condition. To overcome the limitations imposed by the existing measurement technique, a novel thermal sensing element based on Carbon is devised, which is denoted as Large Carbon Cluster. LCC is prepared by single step pyrolysis technique with benzene and ferrocene as precursor mixture. The ratio of precursor mixture is varied to find the proper LCC layer to be formed on a ceramic substrate to get a particular electrical resistance in order to use it as a thermal sensing element. Calibration of the devised carbon allotrope i.e. LCC is found to be having very good thermo-electric characteristics. Several thermal gauges are developed based on LCC for aerodynamic models to test them for the total heat flux rate in Mach 8 hypersonic flow generated in hypersonic shock tunnel – HST2. The performance of the gauges is compared with the existing platinum based thin-film thermal gauges. It is found that the LCC based thin film gauges perform better than platinum thin-film heat transfer gauges. The durability of LCC is also found to be better than platinum. The main aim of finding LCC is that it has good optical absorptivity than any other thermal sensing element; therefore it can be used in radiative heat flux measurements. Aerodynamic models are prepared with the radiative thermal gauges based on LCC and these models are tested in different atmospheric hypersonic test flows. The results reveal that radiative heat flux rate is significantly measured even at lower velocity hypersonic flow conditions. This gives a great confidence on using the LCC based thermal gauges for higher velocity flow conditions and to real time test flights.
APA, Harvard, Vancouver, ISO, and other styles

Book chapters on the topic "Large Carbon Cluster Thin Films"

1

Bettini, Luca Giacomo, Massimiliano Galluzzi, Alessandro Podestà, Paolo Piseri, and Paolo Milani. "Cluster-Assembled Carbon Thin Films." In Springer Handbook of Surface Science, 1217–28. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-46906-1_38.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Bettini, Luca Giacomo, Paolo Milani, and Paolo Piseri. "Cluster-Assembled Carbon Thin Films for Planar Supercapacitors." In Dekker Encyclopedia of Nanoscience and Nanotechnology, Third Edition, 1–7. Taylor & Francis, 2016. http://dx.doi.org/10.1081/e-enn3-120054042.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Rani, Shalu, Sanjay Kumar, and Ritesh Bhardwaj. "Role of Carbon Nanotube for Flexible Supercapacitor Application." In Carbon Nanotubes - Recent Advances, New Perspectives and Potential Applications [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.108022.

Full text
Abstract:
In this current era, with the ever-increasing demand for portable and wearable energy storage devices, the supercapacitor (SC) plays a very positive role to fulfill this gap. Carbon nanotubes (CNTs) are extremely promising material candidate in flexible SC where it works as an electrode to enhance the energy and power densities of the SC because of their remarkable mechanical property, high electrical conductivity, large surface area, and ease to functionalize. Moreover, CNTs can assemble into various macroscopic structures with different dimensions such as single-wall CNTs (SWCNTs), double-wall CNTs (DWCNTs), and multi-wall CNTs (MWCNTs). In this book chapter, a comprehensive discussion on the synthesis, characterization and further utilization of CNTs in metal oxide-based SC has been outlined. Here, the metal oxide can be 1D nanofibers, 2D thin films, and 3D aerogels. Further, a detailed study has been framed on the design methodology and fabrication techniques for the supercapacitor. Recently, various developments and state-of-the-art applications have been proposed for such structures wherein CNTs have been used as electrodes in flexible SCs with varied device configurations such as sandwiched and interdigital in-plane. Furthermore, the flexible CNT-based electrodes have shown great bendability, and compressibility, as well as a long cycle lifetime.
APA, Harvard, Vancouver, ISO, and other styles

Conference papers on the topic "Large Carbon Cluster Thin Films"

1

Smoyer, Justin L., John C. Duda, Pamela M. Norris, and Arthur W. Lichtenberger. "Thermal Boundary Conductance Between Thin Metal Films and Graphite Substrates." In ASME/JSME 2011 8th Thermal Engineering Joint Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajtec2011-44333.

Full text
Abstract:
Due to the high intrinsic thermal conductivity of graphitic structures, much interest has developed in incorporating these materials into modern nano-devices for improved thermal abatement. In order to be integrated successfully, thermal energy must be able to transport efficiently through the graphitic materials and into the surrounding structure, most commonly a metal. However, thermal boundary conductance at metal-graphite interfaces is traditionally poor in comparison to non-graphitic substrates, due in large part to the weak van der Waals adhesion force between the metal and underlying carbon structure. To be applicable as thermal abatement materials, an enhanced understanding of the role of the metal-carbon interface is required. This paper reports the changes to phononic thermal transport across the interface between metallic thin films and highly oriented pyrolitic graphite (HOPG) substrates due to changes in interface structure and chemistry. The temperature dependent thermal boundary conductance is measured using transient thermoreflectance from 100 K to 400 K. It is found that the differences in metal-carbon bonding and structure at the interface have a significant impact on the thermal conductance between the metallic thin films and the HOPG substrates.
APA, Harvard, Vancouver, ISO, and other styles
2

Marciu, D., C. Figura, S. Wang, J. R. Heflin, P. Burbank, S. Stevenson, and H. C. Dorn. "Enhanced Degenerate Four-Wave Mixing in an Endohedral Metallofullerene Through Metal-to-Cage Charge-Transfer." In Organic Thin Films for Photonic Applications. Washington, D.C.: Optica Publishing Group, 1997. http://dx.doi.org/10.1364/otfa.1997.the.15.

Full text
Abstract:
Since the initial discovery and development of a technique for macroscopic preparation of the archetypal and most abundant fullerene C60, a wealth of fullerene-based structures have been produced including higher fullerenes, charge-transfer complexes, fullerene derivatives, superconducting exohedral-doped fullerenes, and carbon nanotubes. One of the most intriguing fullerene classes is the endohedral fullerene in which the spheroidal molecular structure is employed to encapsulate a small number of atoms (one to four) internal to the cage.1,2 Until recently, the difficult separation process of endohedral fullerenes had limited their availability to submilligram levels. Consequently, initial studies of these materials had primarily been restricted to electron paramagnetic resonance (EPR) and linear spectroscopy. EPR measurements demonstrated that, for the case of La@C82, the La atom transfers three electrons to the fullerene cage and resides in the +3 oxidation state.2 Metal-to-cage charge transfer appears to be a common feature of transition metal-containing endohedral metallofullerenes. Meanwhile, nonlinear optical studies of empty-cage C60 and C70 have shown that these materials possess both large third order susceptibilities χ(3)(−ω4;ω1,ω2,ω3)3 (~10-11 esu) and strong optical limiting behavior.4,5 We report here the first nonlinear optical measurements of an endohedral metallofullerene and find a dramatic enhancement in the third order nonlinear optical response. Degenerate four-wave mixing (DFWM) experiments on solutions of the endohedral metallofullerene Er2@C82 show that the metal-to-cage charge transfer provides a mechanism for increasing χ(3)(−ω4;ω1,ω2,ω3) by orders of magnitude relative to empty-cage fullerenes.
APA, Harvard, Vancouver, ISO, and other styles
3

Greve, Daniel R., Tommy Geisler, Thomas Bjørnholm, and Jan C. Petersen. "Third-Order Nonlinear Optical Effects in Organic Nickel Complexes and Triarylmethyl Cations." In Organic Thin Films for Photonic Applications. Washington, D.C.: Optica Publishing Group, 1995. http://dx.doi.org/10.1364/otfa.1995.md.23.

Full text
Abstract:
The second molecular hyperpolarizability, γ, has been determined at 1064 nm by Third- Harmonic Generation (THG) using the Maker fringe technique, for a family of triarylmethyl cations and for a familiy of organic Nickel complexes as guests in PMMA thin films. For the metal complexes it is a well established notion that the low-lying transition with ligand to metal charge transfer character is important for the nonlinear optical properties(1). However, ambiguity arises due to large discrepancies between different measurements(2-5), as well as difficulties in assessing the exact contribution to γ of the ligand to metal charge transfer transition(2,6). To assess the latter question by experimental means, we present here a comparison between a family of Nickel complexes, and triarylmethyl cations. The electronic structure of the triarylmethyl cations resemble that of the metal complexes in the sense that intramolecular charge transfer from the periphery to the central atom takes place upon excitation in the first electronic band. This is shown by semi-empirical PM3 calculations on the three members of the family shown in figure 1. For the amino substituted compound 1 the calculations reveal a significant charge transfer from the amino moiety to the central carbon atom. For the molecules 2 and 3 this effect decreases due to the less efficient donor substituents (2) or forced planarity (3) resulting in more delocalized electronic states both in the HOMO and the LUMO. The observed γ values (table 1) can be correlated with the PM3 calculations in the way that the greater the amount of charge moved and the longer the spatial distance over wich it is moved, the greater is γ. The calculated static γ values, using the semi-empirical PM3/Finite-Field method follow the same trend although much smaller values are obtained.
APA, Harvard, Vancouver, ISO, and other styles
4

Tallman, James A., and Rahul A. Bidkar. "Heat Transfer Coefficient Characterization for Large Aspect-Ratio Thin Films in Film-Riding Seals." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-76168.

Full text
Abstract:
Low-leakage film-riding seals are a key enabling technology for utility-scale supercritical carbon dioxide (sCO2) power cycles. Fluid film-riding rotor-stator seals (operating with sCO2 as the working fluid) are designed to track rotor movements and provide effective sealing by maintaining a tight operating clearance (of the order of several microns) from the spinning rotor. Thin film-riding seals generate viscous shear heat during high-speed operation, and the reliable operation of such thin-film seals depends critically on the designer’s ability to control the thermal deformations of the seal/rotor bearing face, which in turn are tied to the designer’s ability to understand and predict the heat transfer across the seal bearing face. In this paper, we develop a simple axisymmetric thermal-mechanical model of a typical face seal to highlight how the uncertainty in heat transfer coefficient (HTC) on the seal bearing face drives uncertainty in seal deformation predictions, especially when the HTCs are an order of magnitude lower than those predicted with duct-based Dittus-Boelter correlations. This uncertainty in seal bearing face HTCs drives the need for an experimental quantification of HTCs in high-aspect ratio thin films associated with low-leakage film-riding seals. In this paper, we describe a non-rotating experimental test rig designed for estimating the HTCs on the seal bearing face using a shim-heater technique along with IR-camera-based temperature measurements. The experimental set-up consists of a thin metal shim (representing the seal bearing face) forming one wall of a pressurized duct with geometric similarity to a typical thin film of a face seal. Pressurized airflow past the shim is used to simulate the flow field expected in a non-rotating seal. The HTC test data for a non-rotating film (as against the actual seal film with rotating fluid) are lower than the actual seal, and establish a lower bound on the HTCs. This is especially useful for bounding the seal deformation uncertainty, which is vulnerable to the HTCs in the low-HTC regime. We present representative test data that is non-dimensionalized using radial-flow-based Reynolds number and compare these HTC estimates both with the predictions of Dittus-Boelter type correlations, and with the predictions of a 3D computational fluid dynamics (CFD) model. The purpose of the CFD model is to develop a HTC prediction tool for such thin-film surfaces, and the test data are used for validating this predictive model.
APA, Harvard, Vancouver, ISO, and other styles
5

Chen, Xiangli, and Jyoti Mazumder. "Optical emission diagnostics of laser-induced graphite plasma for diamondlike film deposition." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/oam.1990.fc5.

Full text
Abstract:
Motivated by recent interest in laser graphite ablation for optical-quality diamondlike carbon-film deposition, we took emission spectra from a pulsed KrF (3 x 108 W/cm2) excimer laser-induced plasma plume on the surface of bulk graphite. A 0.3 m spectrograph and an optical multichannel analyzer (OMA) were used. In the visible region the plasma emission was dominated by the D-A swan and C-A DesIandres-d'Azambuja bands of C2 and the B-X violet band of CN. No evidence of transitions attributable to C+, C, C3, or larger carbon clusters was found. From the band emission intensity, the vibrational temperatures of the radicals were calculated from the Einstein spontaneous emission coefficients with an assumed Boltzmann population distribution. The results from the different transitions of the C2 swan and CN violet bands all fell within the range of experimental error and uncertainty error in the Einstein coefficients and indicate a vibrational temperature of (13.5 ± 1.3) x 103 K for both radicals. This excellent agreement makes one believe that the species in the plasma are likely to be in local thermodynamic equilibrium. C2 radical concentration is estimated to be 1 × 1015 cm−3 on the basis of emission intensity and Boltzmann distribution at the above temperature.
APA, Harvard, Vancouver, ISO, and other styles
6

Savel’ev, A. B., M. S. Dzjidzjoev, V. M. Gordienko, V. V. Kolchin, S. A. Magnitsky, V. T. Platonenko, and A. P. Tarasevitch. "Resonant High-Intensity Picosecond X-Ray Generation; Thin Films Usage Advantages." In High Resolution Fourier Transform Spectroscopy. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/hrfts.1994.md4.

Full text
Abstract:
Femtosecond laser-induced plasma has proved to be the powerful source of short pulses of incoherent soft X-rays with energy from 50 ev up to few keV and even harder [1,2]. Extremely short X-ray pulse duration down to 1 ps makes it possible to use this radiation in time-resolved X-ray diagnostics of ultrafast processes (X-ray diffraction, spectroscopy, microscopy). It is of special interest to design X-ray microscope in so-called “water window” region to investigate living cells. One more advantage here is as shorter X-ray pulses are used less information recorded is deteriorated by damaging of an investigated cell by X-rays. To generate X-rays above 200 eV intensities of 1015– 1016 W·cm−2 and even higher have to be used. As it was shown previously [3] large amount of X-ray energy emitted from femtosecond plasma consisting of light atomic elements (B,C etc.) is radiated from resonance transitions of highly stripped ions. In the case of carbon target the most bright lines of H- and He-like C ions lie in the “water window” region. The main goals of our research are to find “optimal” conditions for generating powerful few-picosecond X-ray pulses in the vicinity of “water window” region by femtosecond laser pulses with rather low intensities 1015– 1017 W·cm−2 and to investigate whether it is possible to increase electron temperature of the plasma and to generate few keV X-rays by using thin targets.
APA, Harvard, Vancouver, ISO, and other styles
7

Rode, Andrei V., Barry Luther-Davies, and Eugene G. Gamaly. "Laser Ablation of Carbon with High-Pulse-Rate Nanosecond and Picosecond Lasers." In The European Conference on Lasers and Electro-Optics. Washington, D.C.: Optica Publishing Group, 1998. http://dx.doi.org/10.1364/cleo_europe.1998.cmf2.

Full text
Abstract:
We discuss and demonstrate a novel technique for the deposition of high quality thin films via pulsed laser deposition (PLD) using high repetition rate (up to several tens of MHz) picosecond or nanosecond laser pulses. Differences between this method and conventional PLD arise because the pulse energy is markedly reduced compared with the conventional high-energy low repetition rate lasers used for PLD and this significantly improves the quality of the films due to the large decrease (up to nine orders of magnitude) in the number of particles evaporated during a single laser pulse. This effectively eliminates the major disadvantage of PLD which is the formation of particulates in the film.
APA, Harvard, Vancouver, ISO, and other styles
8

Zuhr, R. A., and T. E. Haynes. "Oriented Aluminum Films on Silicon by Direct Ion Beam Deposition." In The Microphysics of Surfaces: Beam-Induced Processes. Washington, D.C.: Optica Publishing Group, 1991. http://dx.doi.org/10.1364/msbip.1991.wc5.

Full text
Abstract:
The formation of metal films on Si at low temperatures is of fundamental interest in thin film physics, as well as a key step in the processing of integrated circuits for microelectronics. If grain size and uniformity could be controlled in the Al metallization used in semiconductor manufacturing, the reliability of such conductors, particularly during thermal cycling, could be greatly improved. One possible way to achieve such control is through the introduction of energy in the form of energetic ions during film growth. [1] The Al on Si system is especially interesting, not only because Al is presently the conductor of choice for microelectronics fabrication, but also because the system exhibits unusual interface properties. [2] It has been demonstrated that oriented crystalline Al films can be grown on Si( 111) and Si(100) surfaces at room temperature by the technique of ionized cluster beam deposition (ICB), even though there is a large mismatch in the size of the respective lattices (25%). [3,4] It is important to determine whether similar oriented growth can be achieved by other thin film deposition techniques and to understand the significant deposition parameters. In this paper we will study the formation of oriented Al films on Si by direct deposition from a low-energy mass-analyzed ion beam.
APA, Harvard, Vancouver, ISO, and other styles
9

Messerly, M. J., H. A. Macleod, J. A. Leavitt, and J. D. Targove. "Porosity and density measurements from Rutherford backscattering analysis (RBS)." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1985. http://dx.doi.org/10.1364/oam.1985.thv3.

Full text
Abstract:
Carbon contamination levels in the 5–15-at. % range have been observed in optical thin films deposited on graphite substrates for RBS analysis. The lack of large amounts of carbon in films grown on beryllium indicates that substrate carbon migrates along columnar boundaries and rests in the voids of films evaporated onto graphite. We originally believed that this excess carbon nullified the RBS results but have found that the stoichiometry and density of films deposited on both C and Be substrates were essentially the same. The depth profile of the carbon contamination then serves as a probe of relative film porosity without interfering with the other elemental determinations.
APA, Harvard, Vancouver, ISO, and other styles
10

Cai, Qingjun, Bing-chung Chen, Yuan Zhao, Julia Mack, Yanbao Ma, Chung-lung Chen, Hengzhi Wang, and Zhifeng Ren. "Thermal Property Measurements of Carbon Nanotube Forest Synthesized by Thermal CVD Process." In ASME 2009 Heat Transfer Summer Conference collocated with the InterPACK09 and 3rd Energy Sustainability Conferences. ASMEDC, 2009. http://dx.doi.org/10.1115/ht2009-88076.

Full text
Abstract:
Carbon nanotube (CNT) forest/cluster synthesized by a thermal CVD process has millimeter growth height, large porosity and nano level pore size, plus high thermal conductivity of individual CNT, thus it is potentially a good wick structure material in developing micro heat transfer devices. However, thermal properties, including effective thermal conductivity (ETC) of a bulky CNT layer, may not be as good as the common metallic wick materials. In this paper, a Netzsch DSC 404 C Pegasus is used for measurement of the CNT heat capacity. CNT volume density is obtained by measuring the ratio of a bulky CNT weight and volume. Both the laser flash and 3-omega measurement methods are employed to measure ETC for CNT wick structures synthesized by the thermal CVD processes. For the laser flash method, measurement deviations caused by reflective silicon and thin substrate are corrected by surface treatment and increased sample thickness. Measurement results of the laser flash indicate that a 600μm thick CNT layer has ETC varying from 0.7–1.2W/m.K. For the 3-omega approach, the measurement system is validated on a quartz substrate. However, the test results yield larger ETC on 250μm CNT samples. Geometric and one dimensional thermal conduction analysis indicate that the bulky CNT thermal properties are tied to CNT synthesis processes. ETC of bulky CNT layer can be enhanced by straightening CNT growth and increasing CNT growth volume density.
APA, Harvard, Vancouver, ISO, and other styles
You might also be interested in the extended bibliographies on the topic 'Large Carbon Cluster Thin Films' for particular source types:
Journal articles
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography