CO2 laser-induced decomposition of methyl iodide sensitized by sulfur hexafluoride

1980 ◽  
Vol 45 (7) ◽  
pp. 1910-1919 ◽  
Author(s):  
Klaus Dathe ◽  
Pavel Engst ◽  
Josef Pola ◽  
Milan Horák
Keyword(s):  
Methyl Iodide ◽  
Co2 Laser ◽  
Decomposition Rate ◽  
Sulfur Hexafluoride ◽  
Continuous Wave ◽  
Gaseous Mixtures ◽  
Exciting Photon ◽  
Irradiation Energy ◽  
Induced Decomposition

Gaseous mixtures of methyl iodide and sulfur hexafluoride yield upon irradiation by a continuous-wave CO2 laser iodine, methane, ethane, ethylene and acetylene - the products of methyl iodide decomposition. The decomposition rate and the mutual ratio of the products is dependent on the delivered irradiation energy, the methyl iodide/sulfur hexafluoride ratio and the energy of the exciting photon. Methyl iodide-d3 in the mixture with SF6 behaves similarly as methyl iodide yielding perdeuterated methane, ethane, ethylene, acetylene and iodine.

CO2 laser-induced decomposition of acetone, 2,3-butanedione and cyclobutanone sensitized by sulfur hexafluoride

1980 ◽  
Vol 45 (6) ◽  
pp. 1805-1811 ◽  
Author(s):  
Josef Pola ◽  
Josef Vítek ◽  
Milan Horák ◽  
Pavel Engst
Keyword(s):  
Acetic Acid ◽  
Reaction Mechanism ◽  
Partial Pressure ◽  
Decomposition Rate ◽  
Laser Power ◽  
Sulfur Hexafluoride ◽  
Buffer Gas ◽  
Sulphur Hexafluoride ◽  
Pyrolytic Products ◽  
Induced Decomposition

The CO2 cw laser powered homogeneous pyrolysis (LPHP) of acetone, 2,3-butanedione and cyclobutanone (all 1.3 - 4kPa) sensitized by sulphur hexafluoride (0.7-1.3kPa) was investigated. The decomposition course of the ketones is analogous to that occuring under conventional pyrolytic conditions. The decomposition rate and the product composition are affected by laser power, partial pressure of the sensitizer, and the buffer gas (helium) added. Besiedes the conventional pyrolytic products, the LPHP of acetone and 2,3-butanedione affords acetylene and that of cyclobutanone produces acetic acid. A possible reaction mechanism of the decompositions is discussed.

IR laser induced decomposition of trifluoroacetic, pentafluoropropionic and heptafluorobutyric anhydrides

1990 ◽  
Vol 55 (10) ◽  
pp. 2460-2467 ◽  
Author(s):  
Pavel Kubát ◽  
Josef Pola
Keyword(s):  
Gas Phase ◽  
Sulfur Hexafluoride ◽  
Continuous Wave ◽  
Parent Compound ◽  
Theoretical Treatment ◽  
Phase Decomposition ◽  
Ir Laser ◽  
Mndo Calculations ◽  
Induced Decomposition ◽  
Heptafluorobutyric Anhydride

The continuous-wave CO2 laser induced gas-phase decomposition of trifluoroacetic, pentafluoropropionic and heptafluorobutyric anhydride, sensitized by sulfur hexafluoride was studied in order to determine the course of the reactions in the absence of wall effects. The decompositions of all the compounds are assumed to involve cleavage of parent compound into acyl fluoride F(CF2)nCOF and .(CF2)nCO2. biradical, the latter undergoing decay into CO and F(CF2)n-1COF compounds. The theoretical treatment of the biradical by MNDO calculations as well as trapping with ethene are presented.

CO2 laser induced decomposition of propylene oxide

1990 ◽  
Vol 55 (10) ◽  
pp. 2455-2459 ◽  
Author(s):  
Marie Jakoubková ◽  
Josef Pola
Keyword(s):  
Thermal Decomposition ◽  
Vinyl Ether ◽  
Co2 Laser ◽  
Propylene Oxide ◽  
Continuous Wave ◽  
Methyl Vinyl ◽  
Isomerization Product ◽  
Primary Products ◽  
Induced Decomposition ◽  
Methyl Vinyl Ether

The continuous-wave (cw) CO2 laser induced decomposition of propylene oxide yields propanal, propanone and methyl vinyl ether as primary isomerization products. The absence of allylol and great amounts of ethene among products of ensuing fragmentation of primary products make the reaction different from conventional thermal decomposition of propylene oxide. CW CO2 laser induced decomposition of methyl vinyl ether affords propanal as isomerization product and shows thermal interconvertibility of propylene oxide and methyl vinyl ether.

Continuous wave CO2 laser driven oxidation of 2-butene and 2-octafluorobutene

1989 ◽  
Vol 54 (11) ◽  
pp. 3083-3087
Author(s):  
Josef Pola ◽  
Josef Vítek
Keyword(s):  
Co2 Laser ◽  
Ground State ◽  
Carbonyl Compounds ◽  
Sulfur Hexafluoride ◽  
Continuous Wave ◽  
Molecular Ground State

CW CO2 laser induced reactions of 2-butene and 2-octafluorobutene with molecular ground state 3O2 oxygen in the presence of sulfur hexafluoride afford products that can be rationalized by means of the earlier proposed mechanism involving transient dioxetane and its cleavage into carbonyl compounds.

Radical Intermediates in Photochemical and Redox Initiated Decomposition of Thioazo Compounds(an EPR and Cyclovoltammetric Study)

1997 ◽  
Vol 62 (6) ◽  
pp. 855-865 ◽  
Author(s):  
Katarína Erentová ◽  
Vladimír Adamčík ◽  
Andrej Staško ◽  
Oskar Nuyken ◽  
Arming Lang ◽  
...  
Keyword(s):  
Decomposition Rate ◽  
Half Life ◽  
Spin Trap ◽  
Solvent Molecule ◽  
Life Time ◽  
Radical Intermediates ◽  
Reactive Radicals ◽  
Induced Decomposition

The cathodically and photochemically induced decomposition of thioazo compounds XC6H4-N2-S-C6H4CH3 and their polymers with X = NO2, COOH, and SO3H were investigated. The formation of carbon-centered XC6H4. and sulfur-centered .S-C6H4Y radicals was confirmed using spin-trap technique. These reactive radicals either abstract hydrogen from CH3CN solvent molecule forming .CH2CN radical or they recombine to cage products XC6H4-S-C6H4CH3 eliminating N2. The decomposition rate of the investigated thioazo compounds is characterized by a formal half-life time of 5 to 10 s.

scholarly journals Thin-Film Processing of Polypropylene and Polystyrene Sheets by a Continuous Wave CO2 Laser with the Cu Cooling Base

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1448
Author(s):  
Nobukazu Kameyama ◽  
Hiroki Yoshida ◽  
Hitoshi Fukagawa ◽  
Kotaro Yamada ◽  
Mitsutaka Fukuda
Keyword(s):  
Thin Film ◽  
Co2 Laser ◽  
Continuous Wave ◽  
Cw Laser ◽  
Heat Effects ◽  
Film Processing ◽  
Carbon Dioxide Co2 ◽  
A Minor ◽  
Residual Heat ◽  
Thin Film Processing

Carbon dioxide (CO2) laser is widely used in commercial and industrial fields to process various materials including polymers, most of which have high absorptivity in infrared spectrum. Thin-film processing by the continuous wave (CW) laser is difficult since polymers are deformed and damaged by the residual heat. We developed the new method to make polypropylene (PP) and polystyrene (PS) sheets thin. The sheets are pressed to a Cu base by extracting air between the sheets and the base during laser processing. It realizes to cut the sheets to around 50 µm thick with less heat effects on the backside which are inevitable for thermal processing using the CW laser. It is considered that the boundary between the sheets and the base is in thermal equilibrium and the base prevents the sheets from deforming to support the backside. The method is applicable to practical use since it does not need any complex controls and is easy to install to an existing equipment with a minor change of the stage.

scholarly journals Threshold of permanent cornea thermal damage due to incidental continuous wave CO2 laser irradiation

2010 ◽  
Vol 14 (2) ◽  
pp. 459-467 ◽  
Author(s):  
Mayada Tahir
Keyword(s):  
Laser Irradiation ◽  
Co2 Laser ◽  
Thermal Damage ◽  
Continuous Wave ◽  
Anterior Part ◽  
Outer Part ◽  
Human Cornea ◽  
Thermal Dose ◽  
Element Analysis ◽  
Reflex Blink

Cornea thermal damage due to incidental continuous wave CO2 laser irradiation is studied numerically based on bio-heat equation. The interaction of laser with tissue leads to a rapid temperature increased in target and the nearby tissue. As the temperature of the eye surface reaches 44?C, a sensation of pain will cause aversion response of the reflex blink and/or shifting away from the source of pain. The aim of the work is to predict numerically the threshold limit of incidental laser power that causes damage to the anterior part of the cornea, which can be healed within 2-5 days as long as damage is not exceeding the outer part of the eye (epithelium). A finite element analysis is used to predict temperature distribution through the cornea where the necroses region can be obtained using thermal dose equation. The thermal dose that required for damaging the cornea is predicted from previously published experimental data on rhesus monkeys and used later as a limit for shrinkage to human cornea. The result of this work is compared by international standard of safety and a good nearby result is obtained which verified the result of this work.

Production of nanomaterials by vaporizing ceramic targets irradiated by a moderate-power continuous-wave CO2 laser

2007 ◽  
Vol 48 (2) ◽  
pp. 292-302 ◽  
Author(s):  
V. N. Snytnikov ◽  
Vl. N. Snytnikov ◽  
D. A. Dubov ◽  
V. I. Zaikovskii ◽  
A. S. Ivanova ◽  
...  
Keyword(s):  
Co2 Laser ◽  
Continuous Wave ◽  
Moderate Power ◽  
Ceramic Targets

The use of a continuous-wave CO2 laser for hardening of wear-resistant high-chromium cast iron

1996 ◽  
Vol 17 (6) ◽  
pp. 607-622 ◽  
Author(s):  
D. M. Gureev ◽  
Yu. M. Matveev ◽  
S. I. Mednikov ◽  
V. K. Shukhostanov ◽  
S. V. Yamshchikov ◽  
...  
Keyword(s):  
Cast Iron ◽  
Co2 Laser ◽  
Continuous Wave ◽  
Wear Resistant ◽  
High Chromium ◽  
High Chromium Cast Iron ◽  
Chromium Cast Iron

scholarly journals Surface alloying of pure iron by molybdenum and tin by a continuous wave CO2 laser

1993 ◽  
Vol 16 (5) ◽  
pp. 331-340
Author(s):  
I S Batra ◽  
K Bhanumurthy ◽  
S K Khera ◽  
A K Sinha ◽  
A R Biswas ◽  
...  
Keyword(s):  
Co2 Laser ◽  
Pure Iron ◽  
Continuous Wave ◽  
Surface Alloying
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