Femtosecond pump–probe studies of chlorine dioxide photochemistry in water and acetonitrile

Philpott, Matthew J.; Hayes, Sophia C.; Reid, Philip J.

doi:10.1016/s0301-0104(98)00204-3

Cited by 36 publications

(68 citation statements)

References 90 publications

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“…Figure 6 shows that the percentage of geminate recombination in water is 60% and it goes down to 20% in acetonitrile and 10% in ethanol. The results in water and acetonitrile are in qualitative agreement with experiments ͑83-80% in water 8,22 and 14 -22% in acetonitrile 18,22 ͒. In ethanol the experimental geminate recombination rate is 50%, which is intermediate between that of water and acetonitrile.…”

Section: Resultssupporting

confidence: 86%

“…The geminate recombination yield is reduced by a factor of 6 when the photodissociation takes place in acetonitrile 18 and by almost a factor of 2 in ethanol. 21 The OClO formed undergoes vibrational relaxation that is approximately three times faster in water than in acetonitrile and ethanol.…”

Section: Introductionmentioning

confidence: 99%

“…8 The goal has been to understand the specific solvent-solute interactions that give rise to the observed effect on the quantum yield of the different photoproducts, as well as to the vibrational relaxation rate of the recombined OClO. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] These studies show that the O and ClO photofragments geminately recombine in water in less than 1 ps to give a ground state OClO with a quantum yield of about 0.8.…”

Section: Introductionmentioning

confidence: 99%

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Molecular dynamics study of the photodissociation of OClO in bulk liquids

Chorny

Vieceli

Benjamin

2002

The Journal of Chemical Physics

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The electronic spectra and the photodissociation dynamics of OClO on the excited state in bulk water, acetonitrile, and ethanol are computed using classical molecular dynamics computer simulations. The trajectories are run on an ab initio potential energy surface of Peterson ͓J. Chem. Phys. 109, 8864 ͑1998͔͒, which is fit to a global three-dimensional analytical surface. The calculated cage escape probability in these liquids seems to correlate with the vibrational relaxation rate of the parent molecule and is in reasonable agreement with experiments in water and acetonitrile, but somewhat overestimates the experimental probability in the case of ethanol.

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Section: Resultssupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Molecular dynamics study of the photodissociation of OClO in bulk liquids

Chorny

Vieceli

Benjamin

2002

The Journal of Chemical Physics

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“…[5][6][7][8] For example, in aqueous solution ⌽ Cl ϭ0.1. 10,12,13,[19][20][21] These studies have shown that geminate recombination occurs on the subpicosecond time scale, and have theorized that the majority of excess vibrational energy available to OClO upon recombination is deposited along the asymmetric-stretch coordinate. Geminate recombination and vibrational relaxation play key roles in the condensed-phase reaction dynamics of OClO.…”

Section: Time Resolved Infrared Absorption Studies Of Geminate Recombmentioning

confidence: 99%

Time resolved infrared absorption studies of geminate recombination and vibrational relaxation in OClO photochemistry

Bolinger

Hayes

Reid

2004

The Journal of Chemical Physics

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Ultrafast time-resolved infrared absorption studies of aqueous chlorine dioxide (OClO) photochemistry are reported. Following photoexcitation at 401 nm, the evolution in optical density at frequencies between 1000 to 1100 cm(-1) is monitored to investigate vibrational energy deposition and relaxation along the asymmetric-stretch coordinate following the reformation of ground-state OClO via geminate recombination of the primary photofragments. The measured kinetics are compared to two proposed models for the vibrational-relaxation dynamics along the asymmetric-stretch coordinate. This comparison demonstrates that the perturbation model derived from molecular dynamics studies is capable of qualitatively reproducing the observed kinetics, where the collisional model employed in previous UV-pump, visible probe experiments demonstrates poor agreement with experiment. The ability of the perturbation model to reproduce the optical-density evolution observed in these studies demonstrates that for aqueous OClO, frequency dependence of the solvent-solute coupling is important in defining the level-dependent vibrational relaxation rates along the asymmetric-stretch coordinate. The absence of optical-density evolution corresponding to the population of higher vibrational levels (n>8) along the asymmetric-stretch coordinate suggests that following geminate recombination, energy is initially deposited into a local Cl-O stretch, with the relaxation of vibrational energy from this coordinate providing for delayed vibrational excitation of the asymmetric- and symmetric-stretch coordinates relative to geminate recombination, as previously observed.

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“…[5][6][7] However, the photochemical production of the ClOO isomer is observed in low-temperature matrixes, [8][9][10] and photolysis of solution-phase OClO results in both ClO/O and ClOO production. [11][12][13][14][15][16][17][18][19][20][21] Another halooxide, dichlorine monoxide (ClOCl), demonstrates phase-dependent photochemical reactivity similar to OClO. In the gas phase, direct dissociation to form Cl and ClO is the dominant photochemical pathway, [22][23][24][25][26][27][28][29][30] whereas, photoexcitation in low-temperature matrixes and in solution results in the formation of the isomer, ClClO.…”

Section: Introductionmentioning

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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Femtosecond pump–probe studies of chlorine dioxide photochemistry in water and acetonitrile

Cited by 36 publications

References 90 publications

Molecular dynamics study of the photodissociation of OClO in bulk liquids

Molecular dynamics study of the photodissociation of OClO in bulk liquids

Time resolved infrared absorption studies of geminate recombination and vibrational relaxation in OClO photochemistry

Femtosecond Pump−Probe Studies of Nitrosyl Chloride Photochemistry in Solution

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