Millbury, OH, United States
Millbury, OH, United States

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De P.K.,Bowling Green State University | De P.K.,Spectra Group Limited, Inc. | Neckers D.C.,Bowling Green State University
Journal of Photochemistry and Photobiology A: Chemistry | Year: 2013

A facile method for preparation of polymer-CdSe quantum dot (QD)-carbon nanotube (CNT) composite under visible light irradiation is described. This photochemical method for such composite formation is based on a photoinduced hole transfer from the CdSe core to the ligand resulting in the formation of polymeric quantum dots on the surface of the CNT. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) methods were used to confirm the formation of thiophene based polymer-QD-CNT composites. The composites maintain the quantum confinement characteristics of the CdSe nanoparticle, retaining its broad absorption in the spectrum of the sun. The composites thus produced can, therefore, be potentially used as the absorbing material in photovoltaic cells. © 2012 Elsevier B.V.


Zheldakov I.L.,University of Kansas | Zheldakov I.L.,Spectra Group Limited, Inc. | Grinevich O.,Spectra Group Limited, Inc. | Mejiritski A.,Spectra Group Limited, Inc. | And 2 more authors.
Photochemistry and Photobiology | Year: 2014

DIBF (5,7-diiodo-3-butoxy-6-fluorone) is a visible light photosensitizer for diaryliodonium salts, the latter being used in cationic photopolymerizations. Although photopolymerization of cycloaliphatic epoxide resins can be initiated by direct excitation of UV-absorbing diaryliodonium salts, such as (p-octyloxy)phenyliodonium hexafluoroantimonate (OPPI), the short wavelengths required cause some practical problems. Sensitizers, of which DIBF is among the best, obviate the deep UV problem by allowing visible-wavelength activation of the photoinitiator. Addition of 9,10-diethoxyanthracene (AN 910 E) dramatically accelerates photopolymerization under visible irradiation of the DIBF/OPPI system. We report herein the transient spectroscopy of the photosensitizer DIBF and discuss likely mechanisms for sensitization of OPPI. Transient absorption spectroscopy examines the role of DIBF as a visible light photosensitizer in cationic polymerization. Rapid intersystem crossing produces a reactive triplet state of DIBF, which subsequently activates an ultraviolet absorbing photoinitiator (OPPI). Addition of 9,10-diethoxyanthracene (AN 910 E) dramatically accelerates polymerization by facilitating the activation of OPPI from the triplet state of DIBF, although electron or energy transfer is too slow to observe within the 1 ns window of the experiment. © 2013 The American Society of Photobiology.


Houk A.L.,University of Kansas | Zheldakov I.L.,University of Kansas | Zheldakov I.L.,Spectra Group Limited, Inc. | Tommey T.A.,University of Kansas | And 2 more authors.
Journal of Physical Chemistry B | Year: 2015

The photoisomerization dynamics of trans-stilbene have been well studied in the lowest excited state, but much less is known about the behavior following excitation to higher-lying electronically excited states. This contribution reports a combined study of the spectroscopy and dynamics of two-photon accessible states above S1. Two-photon absorption (2PA) measurements using a broadband pump-probe technique reveal distinct bands near 5.1 and 6.4 eV. The 2PA bands have absolute cross sections of 40 ± 16 and 270 ± 110 GM, respectively, and a pump-probe polarization dependence that suggests both of the transitions access Ag-symmetry excited states. Separate transient absorption measurements probe the excited-state dynamics following two-photon excitation into each of the bands using intense pulses of 475 and 380 nm light, respectively. The initially excited states rapidly relax via internal conversion, leading to the formation of an S1 excited-state absorption band that is centered near 585 nm and evolves on a time scale of 1-2 ps due to intramolecular vibrational relaxation. The subsequent evolution of the S1 excited-state absorption is identical to the behavior following direct one-photon excitation of the lowest excited state at 4.0 eV. The complementary spectroscopy and dynamics measurements provide new benchmarks for computational studies of the electronic structure and dynamics of this model system on excited states above S1. Probing the dynamics of molecules in their higher-lying excited states is an important frontier in chemical reaction dynamics. (Graph Presented). © 2014 American Chemical Society.


Spectra Group Limited, Inc. | Entity website

Adhesives Spectra Group offers: one component UV/Vis curable adhesives (both free radical AND cationic), mostly for plastics two-component blends for metals and alloys Plastic substrates include: Polycarbonate Acrylic Polypropylene Polypropylene-to-Paper Polyvinyl Chloride (PVC) Polylactic Acid (PLA) If we do not have an off-the-shelf solution, our goal is toCustom Formulate one to fit your specification.Contact us for more information ...


Spectra Group Limited, Inc. | Entity website

Photoinitiators are chemical compounds used to generate reaction intermediates after the absorption of light. In the presence of specific small molecules (liquid monomers) these intermediates are responsible for the production of solids from liquids, (i ...


Spectra Group Limited, Inc. | Entity website

Heterocyclic Compounds Feature molecule of the week 2H-Benzimidazol-2-one, 4-bromo-1,3-dihydro- CAS 40644-16-4, Purity > 99% Synonyms: 4-bromo-2-benzimidazolinone Our heterocyclic compounds catalogs are divided according the specific functional groups. For additional compounds, search our Chemical Database or browse the Benzene Derivatives section ...


Patent
Spectra Group Limited, Inc. | Date: 2014-11-18

A non-biological simulant liquid that includes about 30 to about 95 parts by weight of a polymer dispersion or a wax emulsion or dispersion, about 5 to about 70 parts by weight of a rheology modifying agent, and a pigment or a pigment combination. The non-biological simulant has a viscosity that is shear-dependent, such that the viscosity is from about 30 cP to about 300 cP at a shear rate from 0 s^(1 )to about 10 s^(1), and such that the viscosity decreases when the shear rate increases. The pigment or pigment combination imbues the non-biological simulant with a color that approximates that of human or animal arterial or venous blood.


Patent
Spectra Group Limited, Inc. | Date: 2013-04-12

The present invention relates to compositions and processes for photoinitiating polymerization. Process for photoinitiating polymerization with persulfate anion via photosensitized decomposition of persulfate anion with a composition that includes a light absorber, an electron transfer donor or acceptor, and a persulfate are described.


Grant
Agency: Department of Defense | Branch: Defense Health Program | Program: SBIR | Phase: Phase II | Award Amount: 948.86K | Year: 2012

Development and commercialization of advanced blood simulant system are proposed. The advanced blood simulant will be non-biological and have realistic color, flow, and coagulation properties. The simulant will be developed in tandem with coagulation laminate. The testing will be performed using currently used training hemorrhage simulators. The new advanced blood simulant will be used in training exercises and presentations by military and civilian first responders. As the product will be formulated with waterbased components, it is expected to be inexpensive and easy to clean. The product is projected to have excellent stability and can be stored for years without decrease in level of performance. The product is expected to work with all currently used bleeding simulation systems.


Grant
Agency: Department of Defense | Branch: Defense Health Program | Program: SBIR | Phase: Phase I | Award Amount: 145.97K | Year: 2011

Several approaches to make a fully functional commercial blood simulant are proposed. The simulant will have similar flow characteristics, tactile properties, color, and coagulation capabilities to blood. In this effort, Spectra Group will formulate a p

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