Engineering a low-cost graphene-based electronic device has proven difficult to accomplish via a ... more Engineering a low-cost graphene-based electronic device has proven difficult to accomplish via a single-step fabrication process. Here we introduce a facile, inexpensive, solid-state method for generating, patterning, and electronic tuning of graphene-based materials. Laser scribed graphene (LSG) is shown to be successfully produced and selectively patterned from the direct laser irradiation of graphite oxide films under ambient conditions. Circuits and complex designs are directly patterned onto various flexible substrates without masks, templates, post-processing, transferring techniques, or metal catalysts. In addition, by varying the laser intensity and laser irradiation treatments, the electrical properties of LSG can be precisely tuned over 5 orders of magnitude of conductivity, a feature that has proven difficult with other methods. This inexpensive method for generating LSG on thin flexible substrates provides a mode for fabricating a low-cost graphene-based NO2 gas sensor and enables its use as a heterogeneous scaffold for the selective growth of Pt nanoparticles. The LSG also shows exceptional electrochemical activity that surpasses other carbon-based electrodes in electron charge transfer rate as demonstrated using a ferro-/ferricyanide redox couple.
The University of Rochester's Laboratory for Laser Energetics (LLE) has recently completed the co... more The University of Rochester's Laboratory for Laser Energetics (LLE) has recently completed the construction of the OMEGA EP short-pulse, petawatt laser system. A major structure for OMEGA EP is the grating compressor chamber (GCC). This large (15,750-ft3) vacuum chamber contains numerous optics used in laser-pulse compression of two 40-cm-sq-aperture, IR (1054-nm) laser beams.
Engineering a low-cost graphene-based electronic device has proven difficult to accomplish via a ... more Engineering a low-cost graphene-based electronic device has proven difficult to accomplish via a single-step fabrication process. Here we introduce a facile, inexpensive, solid-state method for generating, patterning, and electronic tuning of graphene-based materials. Laser scribed graphene (LSG) is shown to be successfully produced and selectively patterned from the direct laser irradiation of graphite oxide films under ambient conditions.
ABSTRACT Polyaniline nanofibers modified with transition metal chlorides react with hydrogen sulf... more ABSTRACT Polyaniline nanofibers modified with transition metal chlorides react with hydrogen sulfide to form a stable metal sulfide and HCl, a strong acid. The hydrochloric acid produced dopes the emeraldine base form of polyaniline leading to a large increase in conductivity. The observed response is correlated with the stability of the resulting metal sulfide with Cu> Cd> Zn as indicated by the solubility product constants for the metal sulfides.
Advances in space capabilities are often driven by advances in materials science. Satellite struc... more Advances in space capabilities are often driven by advances in materials science. Satellite structures require durable, lightweight materials that can withstand the physical stresses of launch and operate for extended periods in the extreme environment of space. System capability is largely defined by individual components such as sensors and circuits that combine various materials with different processing requirements.
Titanium nitride films were deposited from tetrakis (ethylmethylamido) titanium and ammonia at 25... more Titanium nitride films were deposited from tetrakis (ethylmethylamido) titanium and ammonia at 250–350° C and 0.7–2 Torr by thermal chemical vapor deposition. The effect of process parameters such as deposition temperature, precursor temperature, carrier gas flow, and ammonia flow on the film properties was studied, the apparent activation energy of film growth was calculated and the film composition was determined. The film step coverage was better than for films grown from tetrakis (dimethylamido) titanium and ammonia.
Abstract Reduced graphite oxide (GO) has shown promise as a scalable alternative to mechanically ... more Abstract Reduced graphite oxide (GO) has shown promise as a scalable alternative to mechanically exfoliated specimens. Although many measurements show that reduced GO has properties approaching those of pristine graphene, it has been difficult to quantify the extent to which the graphitic network is restored upon reduction. Raman spectroscopy is widely used for the characterization of mechanically exfoliated graphene, but has not been fully explored for reduced GO.
Graphene's single atomic layer of sp2 carbon has recently garnered much attention for its potenti... more Graphene's single atomic layer of sp2 carbon has recently garnered much attention for its potential use in electronic applications. Here, we report a memory application for graphene, which we call graphene flash memory (GFM). GFM has the potential to exceed the performance of current flash memory technology by utilizing the intrinsic properties of graphene, such as high density of states, high work function, and low dimensionality.
ABSTRACT Recently we developed a simple, template-free chemical synthesis for polyaniline nanofib... more ABSTRACT Recently we developed a simple, template-free chemical synthesis for polyaniline nanofibers that is selective for nanofibers, can be readily scaled to make large quantities and can be controlled to selectively produce nanofibers with narrow size distributions. Chemical sensors fabricated from polyaniline nanofibers have significantly better performance than conventional material in both sensitivity and time response.
ABSTRACT Contamination-enhanced Laser Induced Damage (CLID) occurs when molecular or particulate ... more ABSTRACT Contamination-enhanced Laser Induced Damage (CLID) occurs when molecular or particulate contamination, present on or in the vicinity of an optical material, leads to accelerated laser power degradation and premature failure. The physical mechanisms that cause CLID are not sufficiently understood to predict the extent to which a contaminant will cause damage.
ABSTRACT The atomic structure of graphene on polycrystalline copper substrates has been studied u... more ABSTRACT The atomic structure of graphene on polycrystalline copper substrates has been studied using scanning tunneling microscopy. The graphene overlayer maintains a continuous pristine atomic structure over atomically flat planes, monatomic steps, edges, and vertices of the copper surface. We find that facets of different identities are overgrown with graphene's perfect carbon honeycomb lattice.
Abstract Several orders of magnitude of change in resistance are observed upon chemical doping an... more Abstract Several orders of magnitude of change in resistance are observed upon chemical doping and dedoping of the conducting polymer polyaniline. This large conductivity range can be utilized to make sensitive chemical sensors. Polyaniline, in its nanofiber form, has even greater sensing capabilities due to the small fiber diameters, high surface area, and porous nanofiber network that enhances gas diffusion into the fibers.
ABSTRACT This paper explores the use of a flow-tube reactor coupled to an FTIR spectrometer to st... more ABSTRACT This paper explores the use of a flow-tube reactor coupled to an FTIR spectrometer to study gas-phase chemical reactions in CVD systems. We show that our apparatus can generate reliable kinetics data by reproducing the literature rate constant for the reaction between 03 and isobutene. We present data from this apparatus on two technologically important systems: TiN from Ti (NMe2) 4 (TDMAT) and NH3 and SiO2 from tetraethoxysilane (TEOS) and 03.
ABSTRACT We have been investigating several chemical microsensor technologies for the detection o... more ABSTRACT We have been investigating several chemical microsensor technologies for the detection of chemicals found in propellant and rocket exhaust plumes and as contaminants for satellite components. In this work we have developed a catalytic metal sensor for the detection of H2 contamination in electronic device packages. The sensor is based on the resistance of a thin film Pd/Ni alloy.
Journal of The American Chemical Society, Jan 1, 1989
Citation data is made available by participants in CrossRef's Cited-by Linking servi... more Citation data is made available by participants in CrossRef's Cited-by Linking service. For a more comprehensive list of citations to this article, users are encouraged to perform a search in SciFinder. ... This article has been cited by 31 ACS Journal articles (5 most recent appear below). ... The sterically encumbering and electron-donating IMes ligands of (IMes)2Ru(Cl)(H )(CO) {IMes = 1,3-bis-(2,4,6-trimethylphenyl)imidazol-2-ylidene} were utilized to access the four-coordinate Ru(II)-hydride complex [(IMes)2Ru(H)(CO)][BAr′4] {Ar′ = 3,5-(CF3)2...
We present arsine gas (AsH3) sensors based on polyaniline nanofiber composites with copper salts ... more We present arsine gas (AsH3) sensors based on polyaniline nanofiber composites with copper salts such as copper (II) bromide that give a large change in resistance in response to parts per million concentrations. A mechanism that involves redox chemistry of the composite metal and AsH3 is proposed and discussed.
Journal of Labelled Compounds & Radiopharmaceuticals, Jan 1, 1983
(2RS,3S)-[4-13C]Valine was diazotized and converted to (2RS, 3S)-[4-13C]-2-bromoisovaleric acid, ... more (2RS,3S)-[4-13C]Valine was diazotized and converted to (2RS, 3S)-[4-13C]-2-bromoisovaleric acid, which on reduction with Zn/HCl gave (3S)-[4-13C] isovaleric acid. This was converted to (3S)-[4-13C] isovaleraldehyde, which was converted by a Strecker synthesis to (2RS,4S)-[5-13C] leucine. Resolution via the N-acetate then gave (2S,4S) and (2R,4S)-[5-13C] leucines. [1-13C] Isovaleric acid was similarly converted to [1-13C] isovaleraldehyde, which, in a Strecker synthesis using K13CN, gave (2RS)-[1,2-13C2] leucine.
Journal of The American Chemical Society, Jan 1, 1987
Citation data is made available by participants in CrossRef's Cited-by Linki... more Citation data is made available by participants in CrossRef's Cited-by Linking service. For a more comprehensive list of citations to this article, users are encouraged to perform a search in SciFinder. ... This article has been cited by 3 ACS Journal articles (3 most recent appear below). ... Dimethylaminonitrene complexes of IMesM+ (IMes =1,3-bis(2,4,6-trimethylphenyl) imidazol-2-ylidene; M = Cu, Ag, Au) were prepared in the gas phase and structurally characterized by high-resolution infrared spectroscopy of the cold species, ion−molecule ...
Journal of The American Chemical Society, Jan 1, 1981
Lysine 2, 3-aminomutase catalyzes the reversible interconversion of L-cy-lysine (la) and LP-lysin... more Lysine 2, 3-aminomutase catalyzes the reversible interconversion of L-cy-lysine (la) and LP-lysine (2). I The air-sensitive enzyme purified to near homogeneity from Clostridium SB4 (C. subterminale strain SB4, ATCC 29748) has an equilibrium constant K=(LPL~ s)/(L-cY-L~ s)= 6.7 at 37 OC and shows stimulation by S-adenosylmethionine, ferrous ion, and pyridoxal phosphate. 2 However, in contrast to most other known aminomutases, the enzyme neither contains nor is stimulated by coenzyme BI2. The interconversion of L-cy-lysine and L-@- ...
Engineering a low-cost graphene-based electronic device has proven difficult to accomplish via a ... more Engineering a low-cost graphene-based electronic device has proven difficult to accomplish via a single-step fabrication process. Here we introduce a facile, inexpensive, solid-state method for generating, patterning, and electronic tuning of graphene-based materials. Laser scribed graphene (LSG) is shown to be successfully produced and selectively patterned from the direct laser irradiation of graphite oxide films under ambient conditions. Circuits and complex designs are directly patterned onto various flexible substrates without masks, templates, post-processing, transferring techniques, or metal catalysts. In addition, by varying the laser intensity and laser irradiation treatments, the electrical properties of LSG can be precisely tuned over 5 orders of magnitude of conductivity, a feature that has proven difficult with other methods. This inexpensive method for generating LSG on thin flexible substrates provides a mode for fabricating a low-cost graphene-based NO2 gas sensor and enables its use as a heterogeneous scaffold for the selective growth of Pt nanoparticles. The LSG also shows exceptional electrochemical activity that surpasses other carbon-based electrodes in electron charge transfer rate as demonstrated using a ferro-/ferricyanide redox couple.
The University of Rochester's Laboratory for Laser Energetics (LLE) has recently completed the co... more The University of Rochester's Laboratory for Laser Energetics (LLE) has recently completed the construction of the OMEGA EP short-pulse, petawatt laser system. A major structure for OMEGA EP is the grating compressor chamber (GCC). This large (15,750-ft3) vacuum chamber contains numerous optics used in laser-pulse compression of two 40-cm-sq-aperture, IR (1054-nm) laser beams.
Engineering a low-cost graphene-based electronic device has proven difficult to accomplish via a ... more Engineering a low-cost graphene-based electronic device has proven difficult to accomplish via a single-step fabrication process. Here we introduce a facile, inexpensive, solid-state method for generating, patterning, and electronic tuning of graphene-based materials. Laser scribed graphene (LSG) is shown to be successfully produced and selectively patterned from the direct laser irradiation of graphite oxide films under ambient conditions.
ABSTRACT Polyaniline nanofibers modified with transition metal chlorides react with hydrogen sulf... more ABSTRACT Polyaniline nanofibers modified with transition metal chlorides react with hydrogen sulfide to form a stable metal sulfide and HCl, a strong acid. The hydrochloric acid produced dopes the emeraldine base form of polyaniline leading to a large increase in conductivity. The observed response is correlated with the stability of the resulting metal sulfide with Cu> Cd> Zn as indicated by the solubility product constants for the metal sulfides.
Advances in space capabilities are often driven by advances in materials science. Satellite struc... more Advances in space capabilities are often driven by advances in materials science. Satellite structures require durable, lightweight materials that can withstand the physical stresses of launch and operate for extended periods in the extreme environment of space. System capability is largely defined by individual components such as sensors and circuits that combine various materials with different processing requirements.
Titanium nitride films were deposited from tetrakis (ethylmethylamido) titanium and ammonia at 25... more Titanium nitride films were deposited from tetrakis (ethylmethylamido) titanium and ammonia at 250–350° C and 0.7–2 Torr by thermal chemical vapor deposition. The effect of process parameters such as deposition temperature, precursor temperature, carrier gas flow, and ammonia flow on the film properties was studied, the apparent activation energy of film growth was calculated and the film composition was determined. The film step coverage was better than for films grown from tetrakis (dimethylamido) titanium and ammonia.
Abstract Reduced graphite oxide (GO) has shown promise as a scalable alternative to mechanically ... more Abstract Reduced graphite oxide (GO) has shown promise as a scalable alternative to mechanically exfoliated specimens. Although many measurements show that reduced GO has properties approaching those of pristine graphene, it has been difficult to quantify the extent to which the graphitic network is restored upon reduction. Raman spectroscopy is widely used for the characterization of mechanically exfoliated graphene, but has not been fully explored for reduced GO.
Graphene's single atomic layer of sp2 carbon has recently garnered much attention for its potenti... more Graphene's single atomic layer of sp2 carbon has recently garnered much attention for its potential use in electronic applications. Here, we report a memory application for graphene, which we call graphene flash memory (GFM). GFM has the potential to exceed the performance of current flash memory technology by utilizing the intrinsic properties of graphene, such as high density of states, high work function, and low dimensionality.
ABSTRACT Recently we developed a simple, template-free chemical synthesis for polyaniline nanofib... more ABSTRACT Recently we developed a simple, template-free chemical synthesis for polyaniline nanofibers that is selective for nanofibers, can be readily scaled to make large quantities and can be controlled to selectively produce nanofibers with narrow size distributions. Chemical sensors fabricated from polyaniline nanofibers have significantly better performance than conventional material in both sensitivity and time response.
ABSTRACT Contamination-enhanced Laser Induced Damage (CLID) occurs when molecular or particulate ... more ABSTRACT Contamination-enhanced Laser Induced Damage (CLID) occurs when molecular or particulate contamination, present on or in the vicinity of an optical material, leads to accelerated laser power degradation and premature failure. The physical mechanisms that cause CLID are not sufficiently understood to predict the extent to which a contaminant will cause damage.
ABSTRACT The atomic structure of graphene on polycrystalline copper substrates has been studied u... more ABSTRACT The atomic structure of graphene on polycrystalline copper substrates has been studied using scanning tunneling microscopy. The graphene overlayer maintains a continuous pristine atomic structure over atomically flat planes, monatomic steps, edges, and vertices of the copper surface. We find that facets of different identities are overgrown with graphene's perfect carbon honeycomb lattice.
Abstract Several orders of magnitude of change in resistance are observed upon chemical doping an... more Abstract Several orders of magnitude of change in resistance are observed upon chemical doping and dedoping of the conducting polymer polyaniline. This large conductivity range can be utilized to make sensitive chemical sensors. Polyaniline, in its nanofiber form, has even greater sensing capabilities due to the small fiber diameters, high surface area, and porous nanofiber network that enhances gas diffusion into the fibers.
ABSTRACT This paper explores the use of a flow-tube reactor coupled to an FTIR spectrometer to st... more ABSTRACT This paper explores the use of a flow-tube reactor coupled to an FTIR spectrometer to study gas-phase chemical reactions in CVD systems. We show that our apparatus can generate reliable kinetics data by reproducing the literature rate constant for the reaction between 03 and isobutene. We present data from this apparatus on two technologically important systems: TiN from Ti (NMe2) 4 (TDMAT) and NH3 and SiO2 from tetraethoxysilane (TEOS) and 03.
ABSTRACT We have been investigating several chemical microsensor technologies for the detection o... more ABSTRACT We have been investigating several chemical microsensor technologies for the detection of chemicals found in propellant and rocket exhaust plumes and as contaminants for satellite components. In this work we have developed a catalytic metal sensor for the detection of H2 contamination in electronic device packages. The sensor is based on the resistance of a thin film Pd/Ni alloy.
Journal of The American Chemical Society, Jan 1, 1989
Citation data is made available by participants in CrossRef's Cited-by Linking servi... more Citation data is made available by participants in CrossRef's Cited-by Linking service. For a more comprehensive list of citations to this article, users are encouraged to perform a search in SciFinder. ... This article has been cited by 31 ACS Journal articles (5 most recent appear below). ... The sterically encumbering and electron-donating IMes ligands of (IMes)2Ru(Cl)(H )(CO) {IMes = 1,3-bis-(2,4,6-trimethylphenyl)imidazol-2-ylidene} were utilized to access the four-coordinate Ru(II)-hydride complex [(IMes)2Ru(H)(CO)][BAr′4] {Ar′ = 3,5-(CF3)2...
We present arsine gas (AsH3) sensors based on polyaniline nanofiber composites with copper salts ... more We present arsine gas (AsH3) sensors based on polyaniline nanofiber composites with copper salts such as copper (II) bromide that give a large change in resistance in response to parts per million concentrations. A mechanism that involves redox chemistry of the composite metal and AsH3 is proposed and discussed.
Journal of Labelled Compounds & Radiopharmaceuticals, Jan 1, 1983
(2RS,3S)-[4-13C]Valine was diazotized and converted to (2RS, 3S)-[4-13C]-2-bromoisovaleric acid, ... more (2RS,3S)-[4-13C]Valine was diazotized and converted to (2RS, 3S)-[4-13C]-2-bromoisovaleric acid, which on reduction with Zn/HCl gave (3S)-[4-13C] isovaleric acid. This was converted to (3S)-[4-13C] isovaleraldehyde, which was converted by a Strecker synthesis to (2RS,4S)-[5-13C] leucine. Resolution via the N-acetate then gave (2S,4S) and (2R,4S)-[5-13C] leucines. [1-13C] Isovaleric acid was similarly converted to [1-13C] isovaleraldehyde, which, in a Strecker synthesis using K13CN, gave (2RS)-[1,2-13C2] leucine.
Journal of The American Chemical Society, Jan 1, 1987
Citation data is made available by participants in CrossRef's Cited-by Linki... more Citation data is made available by participants in CrossRef's Cited-by Linking service. For a more comprehensive list of citations to this article, users are encouraged to perform a search in SciFinder. ... This article has been cited by 3 ACS Journal articles (3 most recent appear below). ... Dimethylaminonitrene complexes of IMesM+ (IMes =1,3-bis(2,4,6-trimethylphenyl) imidazol-2-ylidene; M = Cu, Ag, Au) were prepared in the gas phase and structurally characterized by high-resolution infrared spectroscopy of the cold species, ion−molecule ...
Journal of The American Chemical Society, Jan 1, 1981
Lysine 2, 3-aminomutase catalyzes the reversible interconversion of L-cy-lysine (la) and LP-lysin... more Lysine 2, 3-aminomutase catalyzes the reversible interconversion of L-cy-lysine (la) and LP-lysine (2). I The air-sensitive enzyme purified to near homogeneity from Clostridium SB4 (C. subterminale strain SB4, ATCC 29748) has an equilibrium constant K=(LPL~ s)/(L-cY-L~ s)= 6.7 at 37 OC and shows stimulation by S-adenosylmethionine, ferrous ion, and pyridoxal phosphate. 2 However, in contrast to most other known aminomutases, the enzyme neither contains nor is stimulated by coenzyme BI2. The interconversion of L-cy-lysine and L-@- ...
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