Photoionization mechanism of aniline derivatives in aqueous solution studied by laser flash photolysis

Saito, Fumikazu; Tobita, Seiji; Shizuka, Haruo

doi:10.1016/s1010-6030(97)00048-8

Cited by 57 publications

(75 citation statements)

References 47 publications

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“…Figure 3 (trace A) shows the transient absorption spectrum of the amine DEA obtained 170 ns after excitation at 266 nm in N 2 -purged water/ethanol 99:1. As expected, it shows the typical bands of the DEA cation radical (k max 470 nm) and solvated electron (k max [700 nm) species resulting from efficient one-photon ionization [24]. Upon excitation of the colloidal solution of zeolite BEA-Ag ?…”

Section: Laser Flash Photolysis Measurementssupporting

confidence: 64%

Nanosecond probing of the early nucleation steps of silver atoms in colloidal zeolite by pulse radiolysis and flash photolysis techniques

et al. 2009

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The process of formation and the subsequent aggregation of silver atoms (Ag 0 ) in nanosized zeolite beta (BEA) are studied by transient absorption spectroscopy. The zeolite nanocrystals are stabilized in aqueous colloidal suspensions with a narrow particle size distribution in the range 30-60 nm. The reduction of silver cations is initiated either by pulse radiolysis of the aqueous suspension or by photoinduced electron transfer using an organic electron donor adsorbed in the zeolite framework. The silver atom in BEA nanosized crystals is found to be stable on the microsecond timescale.

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Section: Laser Flash Photolysis Measurementssupporting

confidence: 64%

Nanosecond probing of the early nucleation steps of silver atoms in colloidal zeolite by pulse radiolysis and flash photolysis techniques

et al. 2009

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“…PI corresponds to a relaxation pathway of the excited state of the solute molecule and therefore affects its fluorescence, intersystem crossing, and internal conversion characteristics. Moreover, PI is a multifacet phenomena, since its occurrence depends on numerous factors such as singlet and triplet state energies, excitation light energy and intensity, and the polarity of the medium [1][2][3][4][5][6][7][8]. In solution, photoionization occurs mainly because the photoionization energy (I S ) of a solute is substantially lower than in the gas phase (I G ) due to polarization stabilization of the cation and electron pair in the solvent, this stabilization depending dramatically on the overall polarity of the solvent.…”

Section: Introductionmentioning

confidence: 99%

Tuning the ion formation processes from triplet–triplet annihilation to triplet-mediated photoionization

Jacques¹,

Allonas²,

Sarbach

et al. 2003

Chemical Physics Letters

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Free ion formation in acetonitrile is examined through transient photoconductivity for a set of ketones excited at different wavelengths. According to the photophysical parameters of the ketones and the incident photon energy, two mechanisms can be operative: triplet-triplet annihilation (bimolecular process) and/or photoionization (monomolecular biphotonic process). By using a tunable laser, excited state mediated photoionization was studied. From the threshold energy (E thr ) required for this process to occur, ionization potentials in solution (I S ) were deduced and compared to the corresponding values in gas phase (I G ). A simple energetic model enables the determination of the oxidation potential (E ox ) of the ketones that are compared to the corresponding values obtained through electrochemical measurements.

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“…These values are not far from experimental ones determined for similar compounds, [58] for example, IP(aniline) 7.72 eV. [59] There is experimental precedence for the IP of an N-chloroamine being higher than that for the nonchlorinated compound. [58a, 60] Since the energy of a 308 nm photon is 4.03 eV and the hydration energy of the products of photoionization is about 3.5 eV, [61] in total $ 7.53 eV are available from the 308 nm laser light, a value lower than the calculated IP for 1.…”

Section: Laser Flash Photolysis Studiesmentioning

confidence: 64%

Photo- and Radiation-Chemical Generation and Thermodynamic Properties of the Aminium and Aminyl Radicals Derived fromN-Phenylglycine and (N-Chloro,N-phenyl)glycine in Aqueous Solution: Evidence for a New Photoionization Mechanism for Aromatic Amines

1999

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The generation of N-centered radicals (aminium and aminyl radicals) by photoionization and by pulse-radiolytic one-electron oxidation of N-phenylglycine (1), or by laser flash photolysis or reductive dechlorination of (Nchloro,N-phenyl)glycine (2) has been studied in order to model photodamage to amino acids and proteins, as well as degradation of nitrogen-containing drinking-water pollutants. The aminium radical . (H-N-phenyl)glycine (1 . ), a gdistonic radical zwitterion, was found as a product of photoionization (F PI (1) 0.34, 0.22, 0.30, and 0.01 at 193, 248, 266, and 308 nm) or chemical one-elec-tron oxidation of 1. The aminyl radical . (N-phenyl)glycine (1(N À H) . ), a g-distonic radical anion, is a product of reductive dehalogenation of 2, or of Nchloro photohomolysis, for which the upper limits of F NCl (2) at 193, 248, 266, or 308 nm excitation are 0.61, 0.43, 0.60, and 0.38, or of deprotonation of 1 . (pK a (1 . ) 7.35 AE 0.15). The reduction potential E8(1 . /1) at pH%6 is 0.89 AE 0.02 V versus a normal hydrogen electrode (NHE). The quantum yields of 193, 248, 266, or 308 nm photoionization of 2 are F PI (2) 0.29, 0.10, 0.08, and 0.01. For 1, an additional process leading to 1 . and H . takes place that is identified in terms of water-assisted ionization for which the quantum yields F WA (1) at 193, 248, 266, or 308 nm are 0.37, 0.26, 0.50, and 0.01, respectively. A full thermodynamic description of the system is given, including the different possible acid ± base forms, their redox potentials, and bond dissociation energies.Keywords: amino acids´laser chemistry´photoionizationŕ adical ions´radiochemistryŕ edox chemistry [b] Dr.

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Photoionization mechanism of aniline derivatives in aqueous solution studied by laser flash photolysis

Cited by 57 publications

References 47 publications

Nanosecond probing of the early nucleation steps of silver atoms in colloidal zeolite by pulse radiolysis and flash photolysis techniques

Nanosecond probing of the early nucleation steps of silver atoms in colloidal zeolite by pulse radiolysis and flash photolysis techniques

Tuning the ion formation processes from triplet–triplet annihilation to triplet-mediated photoionization

Photo- and Radiation-Chemical Generation and Thermodynamic Properties of the Aminium and Aminyl Radicals Derived fromN-Phenylglycine and (N-Chloro,N-phenyl)glycine in Aqueous Solution: Evidence for a New Photoionization Mechanism for Aromatic Amines

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