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Search Publications by: Edwin J. Heilweil (Fed)

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Displaying 26 - 50 of 130

Charge Carrier Dynamics and Mobility Determined by Time-Resolved Terahertz Spectroscopy on Films of Nano-to-Micrometer-Sized Colloidal Tin(II) Monosulfide

August 1, 2016
Author(s)
Brian Alberding, Adam Biacchi, Angela R. Hight Walker, Edwin J. Heilweil
Tin(II) monosulfide (SnS) is a semiconductor material with an intermediate band gap, high absorption coefficient is the visible range, and consists of earth abundant, non-toxic elements. For these reasons, SnS has generated much interest for incorporation

Transient Optical and Terahertz Spectroscopy of Nanoscale RuO2

August 1, 2016
Author(s)
Edwin J. Heilweil, Brian G. Alberding, Paul D. Cunningham, Joseph S. Melinger, Jeffrey C. Owrutsky, Adam D. Dunkelberger
Solution-deposited nanoscale films of RuO2, “nanoskins,” are effective transparent conductors because after calcining to 523 K they exhibit flat optical extinction across the visible and infrared combined with relatively high electrical conductivity. Upon

Direct Observation of Carrier Cooling in Organic Semiconductors

July 16, 2015
Author(s)
Edwin J. Heilweil, Paul A. Lane, Paul D. Cunningham, Joseph S. Melinger
Photocurrent in an organic solar cell is generated by a charge transfer reaction between the electron donor and acceptor. The effect of excess excitation energy and the relative contributions of electron and hole transfer are the subject of intense

Ultrafast THz photoconductivity of photovoltaic polymer-fullerene blends: a comparative study correlated with photovoltaic device performance

October 10, 2014
Author(s)
Edwin J. Heilweil, Jin Zuanming, Dominik Gehrig, Clare Dyer-Smith, Frederic Laquai, Mischa Bonn, Dmitry Turchinovich
Ultrafast photo-induced carrier dynamics in prototypical low band-gap polymer:fullerene photovoltaic blend films PTB7:PC70BM and P3HT:PC70BM is investigated using ultrafast terahertz (THz) spectroscopy. The sub-picosecond (ps) and few-ps decays of THz

Time-Resolved Infrared Studies of a Trimethylphosphine Model Derivative of [FeFe]-Hydrogenase

October 1, 2013
Author(s)
Edwin J. Heilweil, Christopher J. Stromberg, Melissa Johnson, James Thuman, Roger G. Letterman, Webster E. Charles
Model compounds that structurally mimic the hydrogen-producing active site of [FeFe] hydrogenases have been explored. In order to explore potential ground-state electronic structure effects on reaction mechanisms compared to hexacarbonyl derivatives, the

Application of nanoporous silicon substrates for terahertz spectroscopy

December 20, 2012
Author(s)
Edwin J. Heilweil, Shu-Zee A. Lo, Gagan Kumar, Thomas E. Murphy
Infrared spectroscopy is a valuable tool for probing and characterizing the macro-molecular motions of complex molecules, including vibrational and phonon modes that cannot be easily accessed through visible spectroscopy. We describe here an improved

Spectra and Relaxation Dynamics of the Pseudohalide (PS) Vibrational Bands for Ru(bpy)2(PS)2 Complexes, PS = CN, NCS and N3

December 5, 2012
Author(s)
Edwin J. Heilweil, Ryan Compton, Helen K. Gerardi, Daniel Weidinger, Douglas J. Brown, Walter J. Dressick, Jeffrey C. Owrutsky
The RuII cyclometalated dye complex, cis-Ru(bpy)2(N3)2 (where bpy = 2,2’-bipyridine), along with two more familiar analogs with pseudohalide (PS) ligands, cis-Ru(bpy)2(NCS)2 and cis-Ru(bpy)2(CN)2, were investigated in solution with static and transient

A SMALL-SAMPLE, BI-DIRECTIONAL SCATTERING MEASUREMENT SYSTEM FROM 200-500 GHz

October 26, 2012
Author(s)
David R. Novotny, Josh Gordon, Edwin J. Heilweil, Brian C. Stillwell, Jeffrey R. Guerrieri, Erich N. Grossman, Shu Z. Lo
Beginning the fall of 2012, NIST will be providing scattering measurements for other government agencies. We present performance results of a bi-directional scattering measurement system in the 200-500 GHz range. The goal is to provide dense-spectrum, bi

Time-Resolved Vibrational Spectroscopy of [FeFe-Hydrogenase Model Compounds

May 21, 2012
Author(s)
Edwin J. Heilweil, Christopher J. Stromberg
Fe2(μ-S2C3H6)(CO)6 is a model compound found to mimic the active site structure of the [FeFe]-hydrogenases. To observe the time-dependent behavior of this molecule, ultrafast ultraviolet (UV) or visible excitation with infrared (IR) probe measurements of

Time-Resolved Infrared Spectroscopy of an [FeFe]-Hydrogenase Model Compound

March 26, 2012
Author(s)
Edwin J. Heilweil
Naturally occurring hydrogenases catalyze the reaction of H+ to form H2 gas. To develop a hydrogen source that is not reliant on fossil fuels, synthetic [FeFe]-hydrogenase model species are being studied. These compounds have a wing-like structure with a

Photoexcitation Dynamics in Nanolayered C60-Zinc Phthalocyanine Films

February 17, 2012
Author(s)
Paul A. Lane, Paul D. Cunningham, Joseph S. Melinger, J. P. Kushto, Okan Esenturk, Edwin J. Heilweil
We elucidate charge transfer and photoexcitation dynamics in C60 and zinc phthalocyanine (ZnPc) by transient and continuous wave spectroscopies. We identify an intermolecular charge transfer state of C¬60 by transient absorption and time-resolved THz and

Development of a combinatorial characterization scheme for high-throughput investigations of hydrogen storage materials.

December 16, 2011
Author(s)
Jason Hattrick-Simpers, Z. Tan, H. Oguchi, Chun Chiu, Edwin J. Heilweil, James E. Maslar, Leonid A. Bendersky
In order to reliably increase the throughput of materials measured for hydrogen storage properties, a complete high-throughput characterization scheme has been developed that accurately measures the hydrogen storage properties of materials in quantities

Engineering Organometallic Femtosecond Chemistry: Photochemistry and Dynamics of Ultrafast Chelation of Cyclopentadienylmanganese Tricarbonyl Derivatives with Pendant Benzenecarbonyl and Pyridinecarbonyl Groups

October 24, 2011
Author(s)
Edwin J. Heilweil, Jermaine O. Johnson, Karen L. Mosley, Phillipe P. Lubet, Webster E. Charles, T J. Burkey
A new method was developed to prepare three cyclopentadienyl manganese tricarbonyl derivatives 1, 4, and 5 with different side chains (Mn{ 5-C5H4CH2COR}(CO)3, R = 2- pyridyl 1, phenyl 4, and 4-pyridyl 5). Steady-state UV-vis, FTIR, and NMR studies in

Pulse Terahertz Reflection/Scattering Measurement

September 7, 2011
Author(s)
Shu Z. Lo, Edwin J. Heilweil
We report a method to measure reflection and scattering from several samples with different degrees of surface roughness and material properties at terahertz frequencies. Reflection from a flat gold mirror shows that the full width half maximum (FWHM) of