Laser Flash Photolysis of HCIO, CIO<sup>−</sup>, HBrO, and BrO<sup>−</sup> in Aqueous Solution. Reactions of Cl‐ and Br‐Atoms

Kläning, Ulrik K.; Wolff, Thomas

doi:10.1002/bbpc.19850890309

Cited by 254 publications

(142 citation statements)

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“…40 The transition responsible for this absorption is the Cl-water complex charge transfer transition, which absorbs throughout the wavelength range from 320 to 390 nm. 43,44 In the region of the probe wavelengths from 440 to 700 nm, an absorption initially rises and decays back to zero. With decreasing probe wavelengths, the rise and decay times of the transient absorption increase; this is easily seen because the temporal width of the absorption profile gets broader.…”

Section: Resultsmentioning

confidence: 99%

“…In addition, if only 4% of the photoexcited OClO undergoes reaction, then the data obtained at the probe wavelength of 350 nm cannot be explained. Using the published extinction coefficients for aqueous Cl 44 and OClO 46 (2500 L mol -1 cm -1 and 900 L mol -1 cm -1 , respectively, at 350 nm), the Cl contribution to the signal at this probe wavelength is in excess of 25%. However, if the total quantum yield is 4%, even if all of the reactive OClO* molecules form Cl, the Cl portion of the transient absorption signal in the 350 nm scan could only comprise 10% of the total signal.…”

Section: Resultsmentioning

confidence: 99%

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Ultrafast Dynamics of Chlorine Dioxide Photochemistry in Water Studied by Femtosecond Transient Absorption Spectroscopy

and

Simon

1996

J. Phys. Chem.

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The ultrafast dynamics of chlorine dioxide (OClO) photochemistry in aqueous solution was studied by femtosecond transient absorption spectroscopy. Following the photoexcitation of OClO at 395 nm, the transient absorption dynamics were probed at 12 different wavelengths ranging from 350 to 700 nm. The transient absorption features observed in the visible wavelengths are assigned to correspond to the vibrationally hot photoisomer ClOO*. The spectral dynamics reveal the vibrational relaxation of this molecule in its ground electronic state. The total vibrational energy relaxation occurs within ∼9 ps. The dynamics of the formation of chlorine atom was examined by measuring the absorption dynamics in the 350-390 nm range. The time constant for Cl formation is calculated to be ∼200 ps. The data show that the dominant pathway for Cl formation is via the isomerized ClOO molecule. No fast component for Cl is detected, indicating that the ClOO molecule reaches thermal equilibrium before dissociating into Cl and O 2 .

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Ultrafast Dynamics of Chlorine Dioxide Photochemistry in Water Studied by Femtosecond Transient Absorption Spectroscopy

and

Simon

1996

J. Phys. Chem.

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“…([AB92] 0 = 200 mg/L, temperature = 333 K, pH 5, [SPS] 0 = 0.5 mM)subsequently intervenes in a series of reactions (Eqs [31][32][33][35][36][37][38][39][40][41] which create either ClO 3 − or • OH[86][87][88][89]:…”

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confidence: 99%

The application of thermally activated persulfate for degradation of Acid Blue 92 in aqueous solution

2019

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Thermally activated persulfate (TAP) was applied for the degradation of Acid Blue 92 (AB92) dye in its aqueous solution. The effects of pH (3-11), temperature (298-333 K), contact time (15-75 min), sodium persulfate (SPS) concentration (0.05-0.5 mM) and initial AB92 concentration (50-400 mg/L) on the degradation of AB92 using TAP were examined. The initial and residual AB92 concentrations were determined spectrophotometrically at the wavelength of 260 nm and the dye mineralization was examined via the total organic carbon analysis. In addition, the chemical oxygen demand was also measured. The activation energy (E a) of AB92 degradation was calculated as 17.38 kJ mol −1 based on the Arrhenius equation. Maximum degradation efficiency of 86.47% was reached after 75 min of treatment at a pH of 5, AB92 concentration of 200 mg/L, SPS concentration of 0.5 mM and temperature of 333 K. The degradation efficiency declined with the addition of different sodium chloride concentrations and organic radical scavengers. AB92 degradation was reduced from 86.5 to 74%, 65, and 59.1% using ethylenediaminetetraacetic acid, tert-butanol, and ethanol, respectively. A kinetic model was also developed to estimate the pseudo-first-order constants as a function of the main operational parameters (initial dye concentration and TAP concentration). Decolorization rate constants (k) of 0.0009, 0.001, 0.0012, 0.0014, and 0.0018 min −1 were obtained at 303, 308, 313, 328, and 333 K, respectively, using the Langmuir-Hinshelwood kinetic model. The results obtained indicate that the TAP degradation process has great potential for the reduction of azo dyes in aqueous environments.

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“…72 The Cl:water and Cl:dichloromethane charge-transfer complexes have similar bandwidths supporting this approximation. 67,75 Next, the concentration of initially photolyzed ClNO ([ClNO] ex ) was determined as follows. The maximum depletion observed at 256 nm in chloroform was -21 mOD, the cell path length in this solvent was 0.095 cm, and ClNO at 256 nm was 1197 M -1 cm -1 .…”

Section: Discussionmentioning

confidence: 99%

Femtosecond Pump−Probe Studies of Nitrosyl Chloride Photochemistry in Solution

2006

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We present a femtosecond pump-probe study of the primary events of nitrosyl chloride (ClNO) photochemistry in solution. Following 266 nm photolysis, the resulting evolution in optical density is measured for ClNO dissolved in acetonitrile, chloroform, and dichloromethane. The results demonstrate that photolysis results in the production of a photoproduct that has an absorption band maximum at 295 nm in acetonitrile and 330 nm in chloroform and dichloromethane. To determine the extent of Cl production, comparative photochemical studies of methyl hypochlorite (MeOCl) and ClNO are performed. Photolysis of MeOCl in solution results in the production of the Cl:solvent charge-transfer complex; therefore, a comparison of the spectral evolution observed following MeOCl and ClNO photolysis under identical photolysis conditions is performed to determine the extent of Cl production following ClNO photolysis. We find that similar to the gas-phase photochemistry, Cl and NO formation is the dominant photochemical channel in acetonitrile. However, the photochemistry in chloroform and dichloromethane is more complex, with a second product formed in addition to Cl and NO. It is proposed that in these solvents photoisomerization also occurs, resulting in the production of ClON. The results presented here represent the first detailed examination of the solution phase photochemistry of ClNO.

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Laser Flash Photolysis of HCIO, CIO⁻, HBrO, and BrO⁻ in Aqueous Solution. Reactions of Cl‐ and Br‐Atoms

Cited by 254 publications

References 10 publications

Ultrafast Dynamics of Chlorine Dioxide Photochemistry in Water Studied by Femtosecond Transient Absorption Spectroscopy

Ultrafast Dynamics of Chlorine Dioxide Photochemistry in Water Studied by Femtosecond Transient Absorption Spectroscopy

The application of thermally activated persulfate for degradation of Acid Blue 92 in aqueous solution

Femtosecond Pump−Probe Studies of Nitrosyl Chloride Photochemistry in Solution

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Laser Flash Photolysis of HCIO, CIO−, HBrO, and BrO− in Aqueous Solution. Reactions of Cl‐ and Br‐Atoms

Cited by 254 publications

References 10 publications

Ultrafast Dynamics of Chlorine Dioxide Photochemistry in Water Studied by Femtosecond Transient Absorption Spectroscopy

Ultrafast Dynamics of Chlorine Dioxide Photochemistry in Water Studied by Femtosecond Transient Absorption Spectroscopy

The application of thermally activated persulfate for degradation of Acid Blue 92 in aqueous solution

Femtosecond Pump−Probe Studies of Nitrosyl Chloride Photochemistry in Solution

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Laser Flash Photolysis of HCIO, CIO⁻, HBrO, and BrO⁻ in Aqueous Solution. Reactions of Cl‐ and Br‐Atoms