Photogeneration of Organic Free Radicals in Liquid Solutions

2020 ◽  
Vol 17 ◽  
Author(s):  
Igor V. Khudyakova ◽  
Peter P. Levinb
Keyword(s):  
Free Radicals ◽  
Uv Light ◽  
Light Sources ◽  
Bond Dissociation Energies ◽  
Light Emitting ◽  
Dissociation Energies ◽  
Electronically Excited State ◽  
Liquid Solutions ◽  
Electronically Excited ◽  
Weak Chemical

In this brief review we consider the generation of free radicals by irradiation with UV-light solutions of compounds with weak chemical bonds. Bond dissociation energies (BDE) are compared with the energies of photons. Light sources used in industry and academia are listed. Free radicals can be produced by photodissociation and by bimolecular chemical reactions between the electronically- excited state of a molecule and a quencher. Important examples are presented. A special effort is devoted to light-emitting diodes (LED) which gain a wide application in this century. We cited books on the free radicals and photochemistry as an introduction as well as recent publications dated 2020.

Performance of the light emitting diodes versus conventional light sources in the UV light cured formulations

2007 ◽  
Vol 105 (2) ◽  
pp. 803-808 ◽  
Author(s):  
Kelechi C. Anyaogu ◽  
Andrey A. Ermoshkin ◽  
Douglas C. Neckers ◽  
Alex Mejiritski ◽  
Oleg Grinevich ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Uv Light ◽  
Light Sources ◽  
Light Emitting

FREE RADICALS BY MASS SPECTROMETRY: X. THE IONIZATION POTENTIALS OF METHYL SUBSTITUTED ALLYL RADICALS

1956 ◽  
Vol 34 (3) ◽  
pp. 345-353 ◽  
Author(s):  
C. A. McDowell ◽  
F. P. Lossing ◽  
I. H. S. Henderson ◽  
J. B. Farmer
Keyword(s):  
Mass Spectrometry ◽  
Free Radicals ◽  
Electron Impact ◽  
Heat Of Formation ◽  
Ionization Potentials ◽  
Bond Dissociation Energies ◽  
Allyl Radical ◽  
Dissociation Energies ◽  
Allyl Halides ◽  
Vertical Ionization Potentials

The vertical ionization potentials of the β- and γ-methyl substituted allyl radicals as measured by electron impact are 8.03 ± 0.05 v. and 7.71 ± 0.05 v, respectively. From appearance potential data the following bond dissociation energies can be derived, assuming the dissociation processes to be free from complications:[Formula: see text]With assumptions about the structure of the ions produced by electron impact from the corresponding butenes the dissociation energies of the C4H7—H bonds in these latter compounds can be estimated, and the heats of formation of the corresponding radicals derived, namely:[Formula: see text]From data on the allyl halides we evaluate the heat of formation of the allyl radical to be:[Formula: see text]

FREE RADICALS BY MASS SPECTROMETRY: VII. THE IONIZATION POTENTIALS OF ETHYL, ISOPROPYL, AND PROPARGYL RADICALS AND THE APPEARANCE POTENTIALS OF THE RADICAL IONS IN SOME DERIVATIVES

1955 ◽  
Vol 33 (5) ◽  
pp. 861-869 ◽  
Author(s):  
J. B. Farmer ◽  
F. P. Lossing
Keyword(s):  
Mass Spectrometry ◽  
Thermal Decomposition ◽  
Free Radicals ◽  
Kinetic Energy ◽  
Electron Impact ◽  
Ionization Potentials ◽  
Bond Dissociation Energies ◽  
Radical Ions ◽  
Dissociation Energies ◽  
Propargyl Radicals

The ionization potentials of ethyl, isopropyl, and propargyl radicals have been measured by electron impact on radicals produced by thermal decomposition of appropriate compounds. The values are:ethyl 8.78±0.05 ev., isopropyl 7.90±0.05 ev., and propargyl 8.25±0.08 ev. From the appearance potentials of these ions in various compounds, the following values of bond dissociation energies were obtained:[Formula: see text][Formula: see text] assuming no kinetic energy of the products.

scholarly journals Double-Sided Freeform Lens for Light Collimation of Light Emitting Diodes

2019 ◽  
Vol 9 (24) ◽  
pp. 5452
Author(s):  
Yong-Sin Syu ◽  
Chun-Ying Wu ◽  
Yung-Chun Lee
Keyword(s):  
Light Emitting Diodes ◽  
Uv Light ◽  
Design Parameters ◽  
Injection Molding Process ◽  
Light Sources ◽  
Molding Process ◽  
Light Emitting ◽  
Uv Led ◽  
Simulation Results ◽  
Freeform Lens

A double-sided freeform lens is proposed for collimating light emitted from light emitting diodes (LEDs). The surface profiles of the lens are mathematically characterized and precisely determined based on a point-source assumption and differential geometry theory. The proposed lens design method is straightforward, flexible, and effective. Moreover, the optical performance of the lens can be intuitively adjusted by tuning just a small number of design parameters. The simulation results showed that the proposed lens achieved an excellent collimating effect for a commercial ultraviolet (UV) LED. A prototype lens is fabricated in UV-grade poly(methyl methacrylate) material using a standard injection molding process. The light collimating effect of the lens/UV-LED assembly was measured experimentally and was shown to be in good agreement with the simulation results. The collimating angle at the half-energy level was equal to 1.88°. The performance of the UV-LED is thus comparable to that of conventional lithography UV light sources based on mercury arc lamps. Consequently, the proposed double freeform lens showed significant potential for photolithography applications within the industry.

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