Reaction Of Fluorine Research Articles

Influence of gasdynamic perturbations on the emission parameters of hydrogen fluoride lasers

An experimental investigation was made of the influence, on the laser radiation parameters, of gasdynamic perturbations (shock wave, rarefaction wave, combustion zone) which arise on initiation of the chemical reaction of fluorine with hydrogen in a closed chamber.

Atmospheric chemistry of CF3COOH: Kinetics of fluorine and chlorine atom reaction at 295 ± 2 K

AbstractUsing a relative rate technique the reactions of fluorine and chlorine atoms with CF3COOH have been determined to proceed with rate constants of (5.6 ± 0.7) × 10−11 and <1 × 10−17 cm3 molecule−1 s−1, respectively. Quoted errors for the F atom rate constant reflect statistical uncertainty (two standard deviations). Systematic errors could add an additional 20% uncertainty. Experiments were performed at 295 ± 2 K and 700 torr total pressure of nitrogen diluent. The reactions of Cl and F atoms with CF3COOH are of no atmospheric importance. Rainout is believed to be the dominant mechanism by which CF3COOH is removed from the atmosphere. The results from this study are discussed with respect to the design and interpretation of laboratory studies of the atmospheric chemistry of CFC replacements. © 1995 John Wiley & Sons, Inc.

Desorption kinetics of copper fluorides in the reaction of fluorine with copper surfaces

The surface reaction of molecular or atomic fluorine beams with single crystal Cu(111) and polycrystalline copper surfaces has been studied at surface temperatures between 760 and 1050 K using laser-induced fluorescence spectroscopy (LIF), Auger electron spectroscopy (AES), and mass spectrometry. Thereby the fluorination of a hot copper sample was found to be an efficient mode of preparing a clean surface as proven by AES. At low surface temperatures CuF and CuF2, as well as Cu3F3 and Cu4F4 clusters are products of the dry etching reaction, desorbing into the gas phase. At high temperatures copper monofluoride, CuF in the X 1Σ+ electronic ground state is the dominant product. The kinetics of CuF desorption has been studied under steady-state conditions as a function of fluorine flux and surface temperature using the LIF approach. These parametric measurements can be fitted to an apparent activation energy, Ea=157±7 kJ mol−1. Further, it was possible to measure the time-resolved CuF desorption. The LIF signal is comprised of a first- and zeroth-order contribution. The observation of the zeroth-order component can be seen as an indication of the formation of fluorinated copper layers which are responsible for the (CuF)n (n=3,4) cluster formation. From the first-order decay the Arrhenius parameters Ea=167±6 kJ mol−1 and A=1011.0±0.4 s−1 are derived. Both values for Ea derived in this study are in reasonable agreement though the latter value is regarded to be more significant. The Arrhenius parameters reflect themselves in a long residual lifetime of CuF molecules once they are formed at the surface in the order of milliseconds at surface temperatures of 1000 K.

Addition of Molecular Fluorine to Azlactones: General Synthetic Method of erythro-.BETA.-Fluorinated .ALPHA.-Amino Acids.

Reaction of molecular fluorine with unsaturated azlactones derived from appropriate aldehydes (or ketones) and benzoylglycine afforded the difluorinated adducts. The reductive amination reaction of the β-fluorinated α-oxoalkanoic acids obtained from the adducts by basic hydrolysis gave erythro-β-fluorinated aliphatic α-amino acids. The same reactions, when applied to methyl 3-phenyl-2-benzoylaminoacrylate, afforded the corresponding aromatic amino acid. Hence, the entire sequence provides a general method for the synthesis of erythro-β-fluorinated α-amino acids.

Investigation of the Reactions of some New Fluorine containing 3-Aroylmethylene-indol-2-ones with Urea and Thiourea Derivatives

Investigation of the Reactions of some New Fluorine containing 3-Aroylmethylene-indol-2-ones with Urea and Thiourea Derivatives

Development of Novel Nickel(β-Diketonate)2.Ligand Complexes as Precursors for Mocvd of Nickel and Nickel Oxide

ABSTRACTVolatile and thermally stable nickel complexes have been prepared by the reaction of fluorine substituted, nickel β–diketonates with neutral (poly)oxygen and (poly)nitrogen donor ligands.These complexes, which have low melting points, have been applied as precursors in MOCVD experiments directed on nickel and nickel oxide deposition. Investigations into the deposition of NiO in porous YSZ via particle precipitation MOCVD, for the development of an anode for a planar Solid Oxide Fuel Cell, are reported.

Investigation of the Reaction of Fluorine containing 1,3-Dihydro-3-( 1 ,5-dihydro-3-methyl-5-oxo-1-phenyl-4Hpyrazol- 4-ylidene )-2H-indol-2-one with Hydrazine Derivatives

Investigation of the Reaction of Fluorine containing 1,3-Dihydro-3-( 1 ,5-dihydro-3-methyl-5-oxo-1-phenyl-4Hpyrazol- 4-ylidene )-2H-indol-2-one with Hydrazine Derivatives

Pyrolysis jet spectroscopy and ab initio studies of the S1 and T1 states of germanium difluoride

Spectra of jet-cooled germanium difluoride were obtained by the reaction of germanium metal and fluorine in the throat of a heated supersonic jet. Two band systems at 331–305 and 231–224 nm were observed by laser-induced emission excitation spectroscopy. On the basis of high quality ab initio predictions of the energies, geometries and vibrational frequencies of the lower electronic states, the two band systems are assigned as ã 3B1–X̃ 1A1 and à 1B1–X̃ 1A1, respectively. The T1–S0 spectrum consists of a long, well-resolved progression in the excited state bending frequency with ν2′ = 192.2 cm−1 and T00=30 582.1 cm−1. The S1–S0 spectrum is a complex tangle of vibronic structure accompanied by a rising background. A partial analysis of the vibronic structure gave ν2′ = 159.6 cm−1 and T00=43 860.9 cm−1. The spectra are very similar to the analogous band systems of GeCl2.

Rotational Analysis of Several Bands in the Ã2A′ ← X̃2A″ System of the FS 2 Free Radical

This paper reports the results of the rotational analysis of five bands of the à 2 A′− X̃ 2 A″ system of the FS 2 free radical. The radical was produced with jet cooling by reaction of molecular fluorine with COS in the body of a continuous-flow supersonic jet. Combination differences from the five bands, plus those of the 3 5 0 band analyzed previously, were used to refine the ground state rotational and spin-rotation constants. The upper state constants were subsequently determined by least-squares fitting the transition frequencies. The upper state geometry for the vibrationless level is estimated to be r(S-F) = 1.642 Å, r(S-S) = 2.09 Å, and θ(FSS) = 97.1°. Axis-switching (Δ K a = 0) transitions were found in all the bands. No perturbations were detected in any of the excited state levels.

The standard molar enthalpy of formation of liquid hydrogen fluoride ΔfHom(HF, l) at the temperature 298.15 K determined by direct combination of the elements in a fluorine-bomb calorimeter

The standard molar enthalpy of formation of liquid hydrogen fluoride ΔfHom (HF, l) = -(303.56 ± 0.27) kJ·mol-1 at T = 298.15 K and po = 101.325 kPa has been measured by direct reaction of gaseous hydrogen and fluorine in a bomb calorimeter. This result, combined with the standard molar enthalpy of solution ΔsolHom(HF, l) reported by Johnson et al. (J. Chem. Thermodynamics1973, 5, 793) gives the standard molar enthalpy of formation of F-(aq) at infinite dilution: ΔfH(F-, aq, 298.15 K) = -(335.66 ± 0.31) kJ·mol-1.

Surface fluorination of poly (phenylene oxide) composite membranes Part I. Transport properties

The effect of surface fluorination on the gas transport properties of composite membranes, comprising an inert porous ceramic support and a selective layer consiting of poly (phenylene oxide), was examined. A small reactor volume permitted the treatment time and the fluorine feed concentration to be investigated independently. The gas transport properties of the treated membranes were evaluated for six gases (N 2, O 2, CH 4, H 2, He and CO 2), in terms of permeance ( P/ l or pressure-normalized flux) and the ideal selectivity for eight pairs of these gases. It was generally found that fluorination at different fluorine feed concentrations and reaction times reduced the permeance of all of the gases. The permeance of the lighter gases (He and H 2) was reduced by a smaller factor than that of the heavier gases (N 2 and CH 4). Fluorination increased the selectivity of He and H 2 relative to N 2 or CH 4 by a small factor, but reduced the selectivity of O 2 and CO 2 relative to N 2 or CH 4. When the membranes were coated with a layer of poly(dimethylsiloxane) (PDMS) subsequent to fluorination, the permeance decreased, considerably more for N 2 and CH 4 than for the other gases. Surface coating also substantially increased the selectivities of all the gas pairs. The largest gains in selectivity after fluorination and coating were found at the higher concentration (0.1 % F 2) and intermediate treatment times of 3 to 5 min. Based on these results, surface coating with PDMS is recommended as a post-treatment step in the fluorination process.

An ab initio study of the reaction of atomic fluorine and chlorine with trifluoroacetaldehyde

In the present work, ab initio molecular orbital theory has been used to examine the reaction of atomic fluorine and chlorine with trifluoroacetaldehyde CF 3C(O)H. Equilibrium geometries and transition state structures have been fully optimized at the unrestricted second-order Møller-Plesset (UMP2/6-31G*) level of theory. Activation barriers and heats of reaction have been estimated using fourth-order Møller-Plesset perturbation theory with spin projection including single, double, triple and quadruple excitations (PMP4 (SDTQ)). The predicted activation barrier for the abstraction of hydrogen from trifluoroacetaldehyde, as from similar compounds, is found to be higher for chlorine than for fluorine atoms. Barriers for hydrogen abstraction are lower for CF 3C(O)H than HFCO, in accord with known trends in substituent effects.

Influence of reactant transport on fluorine reactive ion etching of deep trenches in silicon

The reactive ion etching of silicon by fluorine in high-aspect ratio features was modeled to assess the relative importance of reactant transport on etching rate at the bottom of rectangular trenches. The flux of ions to the feature bottom was found by summing two components: ions arriving directly from the plasma and ions reflected from the sidewalls before reaching the bottom. The transport of neutral reactants within the feature was modeled with diffuse scattering and reaction rates following the kinetics reported by Gray et al. [J. Vac. Sci. Technol. B 11, 1243 (1993)] at all surfaces. The etching rate was found to depend most strongly upon the ion flux under typical process conditions, because of relatively low fluorine reaction probability and low reactant depletion within the feature. Reactant transport limitations are expected to be more important under conditions of low fluorine to ion flux ratio, high-substrate temperature, and high-ion energy.

Low pressure chemiluminescent reaction of molecular fluorine with dimethyl sulfoxide and the effects of added oxygen

The spectra from the chemiluminescent reaction of dimethyl sulfoxide (DMSO) with molecular fluorine have been studied at pressures below 1 Torr. The spectra were examined for changes occurring upon variation of the reactant partial pressures, substitution of deuterated DMSO and the coaddition of molecular oxygen. In the wavelength region 4500–8800 Å, the spectra are dominated by emission from HCF (Ã) or DCF (Ã) at high F 2 concentrations or by emission from CH 2S (ã) or CD 2S (ã) at low F 2 concentrations. Emission from vibrationally excited HF is observed in the hydrogen system but DF is not observed in the deuterium system. Fluorescence and phosphorescence from SO 2 are observed between 2700 and 4500 Å. A weak set of emission bands near 2600 Å is tentatively assigned to SO(A). The addition of O 2 leads to the production of intense emission from OH(A) or OD(A) in the reactions of DMSO-h 6 or DMSO-d 6 respectively. The addition of O 2 to the DMSO-d 6—F 2 system leads to the production of intense chemiluminescence from CD 2O, while CH 2O was totally absent in the analogous reaction of the hydrogen-containing compound. Mechanisms for the formation of the emitters are proposed based on this and previous work.

Laser induced fluorescence and radiative lifetimes of the low-lying electronic states of gaseous AgF

At the fringes of the visible region, two low-lying 1 (Ω=1) electronic states A′Ω1 and aΩ1 of gaseous AgF located ∼4300 cm−1 below the previously known lowest excited A0+ state have been excited for the first time in a silver vapor–fluorine reaction system. The A′Ω1–X 1Σ+ and a Ω1–X 1Σ+ band systems (also observed in chemiluminescence) have been excited and studied using pulsed laser induced fluorescence spectroscopy. The band system associated with the A′Ω1–X 1Σ+ transition has been rotationally analyzed. The UV fluorescence of the A0+ and B0+–X 1Σ+ transitions has also been excited. The radiative lifetimes of these four low-lying electronic states have been measured as 7.1 μs (A′Ω1), 9.1 μs (aΩ1), 240 ns (A0+), and 21 ns (B0+), respectively, revealing that the two Ω=1 states are of triplet character, while the two 0+ states are of singlet character. The observed low-lying states of AgF appear to dissociate adiabatically to neutral atoms in contrast to the apparent dissociation of the low-lying electronic states in CuF to ion pairs. The observation of the low-lying 1 states of AgF also indicates the existence of similar stable 1 states for the remaining silver halides, all of which should absorb visible photons. Major molecular constants of the newly observed A′Ω1 state of 107AgF are Te=24 950.71(10) cm−1, ΔG1/2=506.74(8) cm−1, Be=0.281 32(15) cm−1, De=0.116(60)×10−6 cm−1, and re=1.927 Å.

X-ray photoelectron spectroscopy study of polymer surface reactions in F2 and O2 gases and plasmas

The surface kinetics of polystyrene, polyparaphenylene, and polyvinylmethylketone films in oxygen and fluorine plasmas was studied in a novel reactor which exposes a sample maintained in high vacuum to the species present in a plasma. These polymers were chosen as they contain the same chemical functional groups found in polymers currently used in the semiconductor industry. The reactor configuration enabled the determination of the surface composition using x-ray photoelectron spectrometry as a function of exposure time to the plasma species. The experimental data indicates that the initial reaction probability depends on the functional groups present in the polymer for both atomic oxygen and molecular fluorine attack. Molecular oxygen did not react with any polymers. Polymers containing aromatic functional groups reacted faster with the gas-phase species than polymers containing carbonyl groups. For the reaction of the polymers with an oxygen plasma, production of surface carbonyl and carboxylic acid groups was favored over the formation of surface alcohol species. For the reaction of the polymers with molecular fluorine, formation of surface CF1 species dominated in aromatic containing polymers. The dependence on the functional group was also evident at long reaction times. The effect was most prevalent for the reaction of molecular fluorine with the polymer samples, where the fluorine to carbon ratio for aromatic polymers was more than twice that of a carbonyl containing polymer. Fluorine plasmas were so reactive with all polymers that the effect of the polymer functional group could not be determined. The reaction of the polymers with a fluorine plasma resulted in the formation of surface CF2 species.

First-principles-derived dynamics of a surface reaction: Fluorine etching of Si(100).

We present a realistic simulation of the reaction of fluorine with Si(100). Isothermal molecular dynamics simulations, using an analytic many-body potential fit to first-principles quantum mechanical adsorbate-surface and experimental gas phase data, show the initial buildup of the fluorosilyl layer necessary for etching. Several aspects of the microscopic mechanism are revealed. These simulations represent the first time that first-principles-derived surface reaction dynamics have been carried out; we show that this approach is critical to obtaining physically correct results.

Beam-gas study of bismuth–fluorine reactions using laser-induced fluorescence of BiF

Relative rotational and vibrational populations have been extracted by computer simulation of laser excited fluorescence spectra of BiF (X0+) formed in a thermal molecular beam of bismuth reacting with molecular fluorine under single-collision conditions. The observed rotational distribution is colder than the prior distribution calculated assuming three product fragments. The observed vibrational distribution is also cold, indicating that comparatively little energy is available to the ground state molecules probed. Since the dependence of the detected BiF (X0+) product on the beam time of flight points toward Bi2 as the major beam reactant, the product energy distributions presented here suggest a mechanism in which BiF (X0+), Bi (4S), and F (2P) are formed in an end-to-end attachment of Bi2 and F2. There were no indications that BiF (X0+) can be readily formed by reaction of atomic bismuth.

Hypofluorous acid and acetonitrile: the taming of a reagent

The strong oxidant produced by the reaction of elemental fluorine with acetonitrile containing ca. 10% water has been shown to be hypofluorous acid, HOF, which is stabilized by complexing to the solvent. The reaction represents a new and convenient method of preparing and handling HOF, a unique oxygenating reagent. The presence of acetonitrile results in subtle but significant changes in the chemical behavior of the HOF. Vibrational and NMR spectroscopic studies of the solutions resulting from this reaction, as well as of solutions prepared by dissolving neat HOF in dry acetonitrile, have shown that the complex is a 1:1 hydrogen-bridged entity, in which the HOF proton is most likely bonded to the nitrogen atom of the nitrile. The 19F NMR data indicate that the complexation reaction has an equilibrium constant of ca. 3 at room temperature, and that the enthalpy of formation of the complex is −14.3 ± 0.5 kJ mol −1. The success of this method of synthesizing hypofluorous acid is a consequence of the very slow reaction between HOF and low concentrations of water in acetonitrile. This reaction accelerates drastically as the water content increases. As the solution composition approaches 100% water, the rate constant appears to approach a limit of about 0.7 s −1 at 25 °C, which may be the actual rate of reaction of HOF with the water.

Matrix reactions of sulfur atoms and fluorine. Infrared spectra of sulfur monofluoride, sulfur difluoride and sulfur trifluoride in solid argon

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMatrix reactions of sulfur atoms and fluorine. Infrared spectra of sulfur monofluoride, sulfur difluoride and sulfur trifluoride in solid argonParviz Hassanzadeh and Lester AndrewsCite this: J. Phys. Chem. 1992, 96, 1, 79–84Publication Date (Print):January 1, 1992Publication History Published online1 May 2002Published inissue 1 January 1992https://doi.org/10.1021/j100180a018RIGHTS & PERMISSIONSArticle Views183Altmetric-Citations18LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (790 KB) Get e-Alerts