14989-30-1Relevant academic research and scientific papers
Intracavity laser absorption spectroscopy of HOCI overtones. I. the 3v1+2v2 band and numbers of vibrational states
Abel, Bernd,Hamann, Hilmar H.,Kachanov, Alexander A.,Troe, Juergen
, p. 3189 - 3197 (1996)
The near infrared high-resolution spectra of the a-type transitions of the weak 3v1+2v2 combination band of transient HO35(37)C1 at 12 600 cm-1 has been recorded in an ultrasensitive titaniunrsapphire intracavity laser absorption spectrometer (ICLAS). We report line assignments, new and refined anharmonicity parameters, and the spectroscopic constants for the excited rovibrational states of 3v1+2v2. The Fermi resonance perturbations in this five quanta region, where the internal energy of the molecule is already more than 2/3 of the dissociation energy E0, remain localized and they are the exception, while the extent of intermode mixing and thus intramolecular vibrational energy distribution (IVR) seems to be still small. A Dunham expansion is used for band origin predictions and representations of vibrational states N(E) of HO35C1 up to the dissociation threshold. The results are compared with harmonic and anharmonic numbers of states from a recently proposed stretch-bend coupling model.
Heterogeneous Reactions of Chlorine Nitrate and Hydrogen Chloride on Type I Polar Stratospheric Clouds
Leu, Ming-Taun,Moore, Steven B.,Keyser, Leon F.
, p. 7763 - 7771 (1991)
The heterogeneous reactions ClONO2 + HCl -> Cl2 + HNO3 (1) and ClONO2 + H2O -> HOCl + HNO3 (2) on vapor-deposited HNO3-H2O ice substrates have been investigated at 196 K by using a fast-flow reactor coupled with a quadrupole mass spectrometer.The reaction probability for (1) is 0.10 +/- 0.02 and independent of both the HNO3 and HCl concentrations in the substrate compositions studied.For (2), the reaction probability is approximately 1 * 10-5 near 53.8 wtpercent HNO3, the composition of pure nitric acid trihydrate (NAT), and is about 1 * 10-3 at 46 wtpercent HNO3.The sticking coefficient of HCl on these substrates was also found to be strong function of the substrate composition, ranging from about 2 * 10-5 at NAT composition to 6 * 10-3 at 45 wtpercent HNO3.The HNO3-H2O ice substrates were found to have large internal surface areas, and corrections for gas-phase diffusion within the porous ices were applied to observed loss rates.The large decrease in the HCl sticking coefficient and the reaction probability for (2) as the composition of pure NAT is approached from the water-enriched side can be semiquantitatively explained in terms of a simple two-solid-phase model.Finally, the relation of these results to the depletion of polar ozone is discussed.
Production and trapping of gaseous dimeric ClO: The infrared spectrum of chlorine peroxide (ClOOCl) in solid argon
Cheng, Bing-Ming,Lee, Yuan-Pern
, p. 5930 - 5935 (1989)
The dimeric ClO has been generated in a gaseous discharge-flow system at 220 K and 10-30 Torr by reacting atomic Cl with O3, ClOCl or OClO, and reacting atomic O with ClOCl or OClO, in a stream of Ar.The gas mixture in the flow tube was sampled through a pinhole and condensed on a CsI window maintained at 12 K.The infrared absorption spectrum of the matrix formed after 30-120 min deposition was then recorded.Absorption lines at 752.6, 649.8, and 647.6 cm-1 have been assigned to ClOOCl, and previous assignments for dimeric ClO seem to be in error.The results are inexcellent agreement with recent ab initio calculations.Under our experimental conditions, no other isomer of Cl2O2 was observed.
The electrocatalytic activity of IrO2-Ta2O5 anode materials and electrolyzed oxidizing water preparation and sterilization effect
Ren, Zhandong,Quan, Shanshan,Gao, Jie,Li, Wenyang,Zhu, Yuchan,Liu, Ye,Chai, Bo,Wang, Yourong
, p. 8778 - 8786 (2015)
Ti/IrO2-Ta2O5 anode electrocatalysts with different contents and preparation temperatures were prepared by thermal decomposition in this work. The crystallite characterization and morphology were examined via XRD and SEM. The electrochemical properties were examined via cyclic voltammetry (CV) in 0.5 M H2SO4 and linear sweep voltammetry (LSV) in saturated sodium chloride. Through the study of different series of Ti/IrO2-Ta2O5 anodes, we find that the preparation conditions have a great impact on the electrode catalytic activity. Experimental results indicate that the electrochemically active surface area is determined by the content and morphology of the anode coating. When the IrO2 content and the preparation temperature are 70% and 500 °C, the surface of the electrode is aggregated with segregated crystallite flower-like particles, which brings about the best electrode catalytic activity. The current density in the chlorine evolution reaction of IrO2-Ta2O5 (70% and 500 °C) is 0.4 A cm-2 in saturated sodium chloride. The properties and sterilization effect of EO water are closely related to the electrode catalytic activity. The higher the current density is in chlorine evolution, the higher the available chlorine and HClO content. When the IrO2 content is 70% and the preparation temperature is 500 °C, the maximum values of the killing logarithm value and killing rate are 3.01-3.05 and 99.9023-99.9109%, respectively. In addition, when the Ti substrate undergoes 40 minutes of activation treatment, the Ti/IrO2-Ta2O5 anodes have the highest stability.
Surface sensitive studies of the reactive uptake of chlorine nitrate on ice
Berland,Tolbert,George
, p. 9954 - 9963 (1997)
The reactive uptake of chlorine nitrate (ClONO2) on ice surfaces (ClONO2 + H2O → HOCl + HNO3) was studied with surface sensitivity using laser-induced thermal desorption (LITD) techniques. Thin films of vapor-deposited ice were exposed to ClONO2 vapor at substrate temperatures from 75 to 140 K. The reactive uptake of ClONO2 was directly measured by monitoring the hydrolysis reaction products, HOCl and HNO3, on the ice surface in real time. At low temperatures from 75 to 110 K, the HOCl coverage initially increased rapidly with ClONO2 exposure, indicating an efficient hydrolysis reaction. After longer ClONO2 exposures, the rate of HOCl production decreased and the HOCl reached a constant coverage. A reaction probability of γ = 0.03 was calculated for the reactive uptake of ClONO2 on ice and was independent of temperature from 75 to 110 K. At temperatures greater than 110 K, the reaction probability decreased with increasing temperature and reached a value of γ= 0.005 at 140 K. This decrease in the reaction probability with increasing substrate temperature is consistent with a precursor-mediated adsorption model. The good fits to the precursor-mediated adsorption model indicate that the ClONO2 hydrolysis reaction has a low activation barrier. The precursor-mediated adsorption model extrapolated to stratospheric temperatures predicts a reaction probability that is significantly lower than the accepted literature value of γ 0.3. This discrepancy may be caused by the higher pressures and the dynamic ice surface at stratospheric conditions that could enhance the reaction probability. The constant HOCl coverage reached after longer ClONO2 exposures is attributed to the poisoning of the ice surface by product HNO3. Calibrated HNO3 signals at 86 and 140 K revealed that the ClONO2 hydrolysis reaction is inhibited at a nitric acid coverage of 7.5 × 1014 molecules/cm2 or 1 monolayer. This coverage suggests that the hydrolysis reaction is limited to the surface or near-surface region of ice at these low temperatures.
State selected unimolecular dissociation of HOCl near threshold: The 6vOH vibrational state
Dutton, Gregory,Barnes, Rhett James,Sinha, Amitabha
, p. 4976 - 4992 (1999)
The spectroscopy and unimolecular dissociation dynamics of HOCl are examined by accessing rotational resonances of the 6vOH vibrational level over the Ka=0-5 manifolds using overtone-overtone double resonance. The spectroscopic analysis indicates that state mixing between the zeroth-order bright O-H stretching overtone state, 6 0 0, and dark background vibrational levels is incomplete as the bright state couples to only a fraction of the available states. The coupling of 6 0 0 to a set of nearby dark states is mediated primarily by anharmonic coupling with the fourth-order vibrational resonance k1,233 playing a particularly important role through its ability to couple the 6 0 0 state directly to the 5 2 1 vibration and indirectly to the 4 4 2 vibration. The measured state-specific unimolecular dissociation rates for 6 0 0 show large fluctuations with J and Ka and are substantially slower than that expected on the basis of statistical theory. The rate fluctuations are interpreted on the basis of spectroscopic data which suggest that the fluctuations arise as a result of variation in state mixing as different dark vibrational states come in and out of resonance with the bright state for different values of J and Ka.
Kinetic mechanism of ClONO2 uptake on polycrystalline film of NaCl
Zelenov,Aparina,Kashtanov,Shestakov,Gershenzon
, p. 6771 - 6780 (2006)
Kinetic studies and the mechanism determination of ClONO2 uptake on polycrystalline NaCl were carried out using a coated-insert flow tube reactor combined with high-resolution, low-energy electron-impact mass spectrometer under the following conditions: p =1-2 Torr, linear flow velocity v = 3.5-75 m s-1, T = 293 and 387 K, [ClONO2] = (0.5-25) × 1012 molecules cm-3. The salt was deposited as a film from nonsaturated aqueous solution on the sliding rod. The temporal dependences of the uptake coefficient and the partial uptake coefficients leading to a formation of the prime Cl2 and HOCl products were measured for different ClONO2 concentrations. These dependences are established to be described by γ = γ0 exp(-t/τ) + γs, γ0.s-1 = a0.S + b0.s[ClONO2]. In the framework of the proposed kinetic model, the data are explained and the main elementary kinetic parameters of the uptake are evaluated. The model is based on a combination of Langmuir adsorption, formation of surface complexes on initial active sites, Z ch, followed by their unimolecular decomposition. Decomposition is proposed to proceed concurrently in two channels, one of which is a released surface site that conserves the properties of the initial site. In the other channel, the initial Zch transforms into Zph followed by steady-state uptake and reproduction of final Zph. The model gives an analytical expression for experimental parameters γ0, γs, and τ in terms of elementary rate constants and the reactant volume concentration. The final objective of the proposed model is the extrapolation of γ0, γs, and r parameters to real tropospheric conditions.
Studies of reactions of importance in the stratosphere. IV. Rate constant for the reaction Cl + HOCl--> HCl + ClO over the temperature range 243-365 K
Cook, Jac-E L.,Ennis, Christine A.,Leck, Thomas J.,Birks, John W.
, p. 545 - 549 (1981)
The title reaction was studied over the temperature range 243-365 K using the discharge flow technique with mass spectrometry for detection.The rate constant was measured by detecting the loss of HOCl in the presence of a large excess of chlorine atoms.The resulting temperature dependent rate constant is given by k = (3.0 +/- 0.5) * 10-12exp cm3 molecule-1 s-1, where the stated errors include our estimate of the maximum possible systematic error.This reaction becomes a significant pathway to HCl in the stratosphere when the total ClX exceeds 10 ppbv.Upper limits for rate constants for the reactions HOCl + NO --> products and HOCl + O3 -> products at 300 K were established to be 1.0 * 10-17 and 4.0 * 10-16 cm3 molecule-1 s-1, respectively.
Temperature Dependence of the HO2 + ClO Reaction. 1. Reaction Kinetics by Pulsed Photolysis-Ultraviolet Absorption and ab Initio Studies of the Potential Surface
Nickolaisen, Scott L.,Roehl, Coleen M.,Blakeley, Lisa K.,Friedl, Randall R.,Francisco, Joseph S.,Liu, Ruifeng,Sander, Stanley P.
, p. 308 - 319 (2000)
The kinetics of the HO2 + ClO reaction was studied using the flash photolysis/ultraviolet absorption technique over the temperature range 203-364 K and pressure range 50-700 Torr of N2. In contrast to previous work, the temperature dependence displayed linear Arrhenius behavior over the entire temperature range with the rate constant being described by the expression k(T) = 2.84 × 10-12 exp{(312 ± 60)/T} cm3 molecule-1 s-1. Ab initio calculations of intermediates and transition states have been carried out on the singlet and triplet potential energy surfaces. These calculations show that the reaction proceeds mainly through the ClO-HO2 complex on the triplet surface; however, collisionally stabilized HOOOCl formed on the singlet surface will possess an appreciable lifetime due to large barriers toward decomposition to HCl and HOCl. Termolecular rate calculations using ab initio parameters lead to a strong collision rate constant of ～5 × 10-32 cm6 molecule-2 s-1 for HOOOCl formation. This intermediate may be important under both laboratory and atmospheric conditions.
The hydrolysis of chlorine nitrate on ice is autocatalytic
Geiger, Franz M.,Pibel, Charles D.,Hicks, Janice M.
, p. 4940 - 4945 (2001)
A key chemical reaction in stratospheric ozone depletion is the reaction of chlorine nitrate (ClONO2) with water. This reaction is known to be catalyzed in the presence of ice particles found in polar stratospheric clouds (PSCs). However, the mechanism and time scale of the reaction, and the role of the ice surface, are not well understood. This surface second harmonic generation study shows that the submonolayer ClONO2 hydrolysis on basal ice (Ih) surfaces at 185 K occurs autocatalytically, with the product molecule HOCl acting as the autocatalyst. The other product, HNO3, acts to delay the reaction. The hydrolysis reaction is surprisingly slow, with induction times that range from 100 to 1000 s, depending upon how much reactant is initially present. It is proposed that the ice surface serves as a reservoir, enabling the reaction to be acid catalyzed.
