7791-21-1Relevant academic research and scientific papers
On the high-resolution HeI photoelectron spectrum of Cl2O
Motte-Tollet,Delwiche,Heinesch,Hubin-Franskin,Gingell,Jones,Mason,Marston
, p. 452 - 458 (1998)
The high-resolution HeI (58.4 nm) photoelectron spectrum of dichlorine monoxide, Cl2O, has been recorded in the region of the four lowest-energy ionic electronic states. Formation of the ion in its ground and excited electronic states is accomp
Absolute cross sections for the VUV optical absorption of Cl2O in the 6.5-9.7 eV energy range
Motte-Tollet,Ska,Marston,Walker,Siggel,Gingell,Kaminski,Brown,Mason
, p. 298 - 306 (1997)
The VUV photoabsorption spectrum of dichlorine monoxide has been recorded between 6.5 and 9.7 eV photon energies using the UK Daresbury Synchrotron Radiation facility. The spectrum consists of a broad structureless band centred at 7.25 eV followed by several vibrationally resolved high-intensity bands. The 7.25 eV band has been interpreted in terms of the excitation of a dissociative valence excited state while the higher-energy electronic bands (above 7.5 eV) have been classified into several (n = 3, 4) Rydberg states linked with the ionic ground state and its lowest-energy excited states. An analysis of the vibrational progressions associated with the excitation of the various Rydberg states has been completed.
Kinetics of the ClO + NO2 + M Reaction
Molina, Mario J.,Molina, Luisa T.,Ishiwata, Takashi
, p. 3100 - 3104 (1980)
The ClO + NO2 + M reaction has been studied with two techniques: Fourier transform infrared spectroscopy of the products, and flash photolysis-ultraviolet absorption to monitor the decay of ClO in excess NO2.The measured third-order rate constant is 1.5E-31 cm6 molecule-2 s-1 at 298 K with M=N2, in good agreement with previous literature values, but the rate constant appears to decrease by up to a factor of 3 in the presence of increasing amounts of OClO.For the infrared studies a stoichiometric mixture of ClO and NO2 was prepared in a flow system by mixing NO with OClO; at least as much NO2 as ClONO2 was produced under a variety of experimental conditions.These two sets of results are incompatible with the assumption made in previous kinetic studies that ClONO2 is the only recombination product; other isomers such as OClONO or ClOONO are likely to be formed three to four times faster.These results imply that potential stratospheric ozone depletion due to chlorofluoromethanes may be even larger than previously thought.
Rate Coefficient for the Termolecular Channel of the Self-Reaction of ClO
Trolier, M.,Mauldin, R. L.,Ravishankara, A. R.
, p. 4896 - 4907 (1990)
The rate coefficient for the reaction ClO + ClO -> Cl2O2 has been measured by using a flash photolysis/UV absorption technique at temperatures from 200 to 263 K and pressures from 25 to 600 Torr in N2, O2, He, and SF6.Conventional single-wavelength detection and diode array spectrometry have both been employed in monitoring the reactant and product species.The UV absorption cross section of ClO has been measured in the same temperature range, from 220 to 350 nm, by using the diode array, and at 282.65 nm (the maximum of the ClO (9,0) band) by using the single-wavelength detection.The reactions of chlorine atoms with O3 and Cl2O have been used to produce ClO.The title reaction is believed to play a role in the loss of ozone from the Antarctic stratosphere during the austral spring.At the temperatures and pressures relevant to the Antarctic stratosphere, our measured values agree with the recent work of Sander et al. and are considerably smaller than the values obtained by Hayman et al.Over the range of conditions relevant to the Antarctic ozone loss, our measurements differ from Hayman et al. by a factor ranging from 1.3 to 3.0, with the discrepancy being ca. 1.9 at the altitude of maximum ozone loss.We have found Cl2O2 to be the major product of this reaction under these conditions, and we have established an upper limit of 1percent for the production of OClO.
Kinetic and Mechanistic Study of X + ClOCl -> Products (X = Br, Cl, F, O, OH, N) over the Temperature Range 240-373 K
Stevens, Philip S.,Anderson, James G.
, p. 1708 - 1718 (1992)
The rate constants for the reactions of X + ClOCl -> products for X = Br, Cl, F, O, OH, and N have been measured over the temperature range 230-400 K.The rate constants are (in units of cm3 molecule-1 s-1) as follows: (2.1 +/- 0.2) x 10-11 exp for Br + ClOCl; 6.0 +/- 0.6) x 10-11 exp for Cl + ClOCl; (1.5 +/- 0.5) x 10-10 exp for F + ClOCl; (1.3 +/- 0.8) x 10-11 exp for O + ClOCl; (1.7 +/- 0.8) x 10-12 exp for OH + ClOCl; and k298 -15 for N + ClOCl.The rate constants for X = Br, Cl, F, and N are found to correlate with the electron affinity of the attacking radical, suggesting that the mechanism for these reactions involves the partial transfer of an electron from ClOCl to X, and the activation energy for reaction is determined by the ability of the transition state to accommodate the shift in electron density.This trend is similar to that found for a number of non-hydrogen abstraction reactions (X + ClNO, O3, Cl2), where the reactivity scales with the quantity IP(molecule) - EA(radical), where IP refers to the ionization potential and EA the electron affinity.The reactions of O and OH with ClOCl are significantly faster than predicted by the trend, suggesting that the electron-transfer mechanism is not the only driving force in these reactions, which may involve long-range attractive forces leading to stable intermediates.
CIO radical yields in the reaction of O(1D) with Cl2, HCl, chloromethanes, and chlorofluoromethanes
Feierabend, Karl J.,Papanastasiou, Dimitrios K.,Burkholder, James B.
, p. 12052 - 12061 (2010)
Absolute CIO radical product yields in the gas-phase reactions of O( 1D) with Cl2, HCl, CCl4, CHCl3, CH 2Cl2, CH3Cl, CFCl3, CF 2Cl2, CF3Cl, CHFCl
The ultraviolet photodissociation of Cl2O at 235 nm and of HOCl at 235 and 266 nm
Tanaka, Yoshiki,Kawasaki, Masahiro,Matsumi, Yutaka,Fujiwara, Hisashi,Ishiwata, Takashi,Rogers, Leon J.,Dixon, Richard N.,Ashfold, Michael N. R.
, p. 1315 - 1323 (1998)
The primary photochemistry of gas phase dichlorine monoxide (Cl2O) and of hypochlorous acid (HOCl) following excitation at 235 nm has been investigated using photofragment ion imaging to obtain the recoil velocity and angular distributions of the ground (2P3/2) and spin-orbit excited (2P1/2) atomic chlorine products. In the case of Cl2O, both Cl spin-orbit products exhibit angular distributions characterized by an anisotropy parameter, β=1.2±0.2, consistent with previous interpretations of the ultraviolet (UV) absorption spectrum of Cl2O which associate the broad intense absorption feature peaking at λ～255nm with excitation to a (bent) dissociative state of 1B2(C2v) symmetry. The recoil velocity distributions of the two Cl spin-orbit products are markedly different. The ground state atoms (which constitute >90% of the total Cl atom yield) are partnered by ClO fragments carrying significantly higher average levels of internal excitation. The slowest Cl atoms are most readily understood in terms of three body fragmentation of Cl2O to its constituent atoms. These findings are rationalized in terms of a model potential energy surface for the 11B2 state, which correlates diabatically with ClO(X) radicals together with a spin-orbit excited Cl atom, with efficient radiationless transfer to one (or more) lower energy surfaces at extended Cl-O bond lengths accounting for the dominance of ground state Cl atom fragments. The image of the ground state Cl atoms resulting from photolysis of HOCl at 235 nm is consistent with parent excitation via a transition for which the dipole moment is closely aligned with the Cl-O bond, followed by prompt dissociation (β=1.7±0.2) with the bulk of the excess energy partitioned into product recoil. Such conclusions are consistent with the results of laser induced fluorescence measurements of the OH(X) products resulting from 266 nm photodissociation of HOCl which reveal OH(X) products in both spin-orbit states, exclusively in their zero-point vibrational level, and carrying only modest levels of rotational excitation (well described by a Boltzmann distribution with Trot～750±50K).
Heterogeneous chemistry of Cl2O and HOCl on frozen natural sea salt, recrystallized sea salt, KCl and NaCl solutions at 200 and 215 K
Pratte, Pascal,Rossi, Michel J.
, p. 1119 - 1150 (2010)
The HOCl heterogeneous reaction on frozen natural (NSS) and recrystallized (RSS) sea salt, KCl and NaCl solutions was studied using a low pressure flow reactor in order to measure the uptake coefficient γ and products of reaction. The HOCl sample used in these experiments always contained up to 25% Cl2O which was also studied separately as a pure gas in order to understand the heterogeneous chemistry of both gases. By performing HOCl uptake on frozen NSS solution at 200 K and a gas-phase residence time of (1.6±0.6) s we obtained a steady state uptake coefficient γHOCl on NSS = (2.5±0.7)×10-3 and ?Cl2O on NSS = (2.8±0.8)×10-3. On frozen KCl solution at 200 K we obtain ?HOCl on KCl = (2.8±1.3)×10-3, identical to NSS, and ?Cl2O on KCl = (4.6±0.8)×10-4. The main product formed during the uptake on frozen NSS solution is Cl2 which is sustained for at least one hour. In contrast, only a transient Cl2 flow (pulse) decreasing on the time scale of 100 s was observed on frozen KCl (NaCl) solution. 25±10 % of the HOCl taken up on all chloride-containing frozen substrates at 200 K react to produce Cl2 at high HOCl concentration (4.5×1011 molecule cm-3) and at a residence time of 1.6 s in comparison with twice that for Cl2O. For smaller concentrations such as [HOCl] = 3.7×1010 molecule cm-3 and.or a shorter residence time (0.137±0.004s), HOCl uptake did not generate Cl2 in contrast to Cl2O. A single Br2 burst event was monitored when a Cl2O or HOCl.Cl2O mixture is taken up on fresh frozen NSS solution during the first uptake at 200 K. Further Cl2O or HOCl.Cl2O uptake on the same sample, even after annealing at 240 K does not show an additional Br2 pulse. This Br2 release may be significant in the autocatalytic ozone destruction mechanism in the troposphere during polar sunrise. Some of the atmospheric implications of the present results are highlighted with emphasis on the preequilibrium Cl2O(ads) + H2O(ice)→←2 HOCl(ads) between adsorbed HOCl and Cl2O, with the latter being the gateway to reactive uptake of HOCl at low temperatures. by Oldenbourg Wissenschaftsverlag.
Dissociation pathways in low energy (0-2 eV) electron attachment to Cl2O
Sailer, Wolfgang,Tegeder, Petra,Probst, Michael,Drexel, Herwig,Grill, Verena,Scheier, Paul,Mason, Nigel J.,Illenberger, Eugen,M?rk, Tilmann D.
, p. 471 - 478 (2001)
Dissociative electron attachment (DA) to ClOCl is studied in a high resolution crossed beam experiment. Two complementary ion pairs, Cl-/ClO- and O-/Cl2-, are observed. The Cl-/ClO- pair arises from a simple Cl-OCl bond cleavage with the electron sitting on either of the two fragments. The O-/Cl2- pair is formed by a concerted reaction with the expulsion of O- (or O) and formation of Cl2 (or Cl2-). Ab initio calculations indicate that in low energy electron attachment an electronically excited state of the precursor anion (ClOCl-* (2B2)) is involved.
UV absorption spectrum of the ClO dimer (Cl2O2) between 200 and 420 nm
Papanastasiou, Dimitrios K.,Papadimitriou, Vassileios C.,Fahey, David W.,Burkholder, James B.
, p. 13711 - 13726 (2010/05/11)
The UV photolysis of Cl2O2 (dichlorine peroxide) is a key step in the catalytic destruction of polar stratospheric ozone. In this study, the gas-phase UV absorption spectrum of Cl2O2 was measured using diode arr
