Naphthalene pulse radiolysis

Hayon23 studied the yields of ions and excited states in pulse radiolysis of liquid DMSO using anthracene as a solute to determine the yield of free ions and naphthalene as a solute to measure the yield of triplet excited states. Anthracene is known to react with solvated electrons to give the anthracene radical anion, A T... 

From the pulse radiolysis of DMSO solutions of naphthalene and the absorption of the naphthalene triplets (e = 2.26 x 104 M "1 cm 1) Hayon23 found that the yield of triplet excited states in irradiated DMSO is G = 0.57 and G = 0.36 for DMSO saturated with argon gas or N20 gas, respectively. 

Kemp and coworkers employed the pulse radiolysis technique to study the radiolysis of liquid dimethyl sulfoxide (DMSO) with several amines as solutes [triphenylamine, and N, A, A, N -tetramethyl-p-phenylenediamine (TMPD)]. The radiolysis led to the formation of transient, intense absorptions closely resembling those of the corresponding amine radical cations. Pulse radiolysis studies determine only the product Ge, where G is the radiolytic yield and e is the molar absorption. Michaelis and coworkers measured e for TMPD as 1.19 X 10 m s and from this a G value of 1.7 is obtained for TMPD in DMSO. The insensitivity of the yield to the addition of electron scavenger (N2O) and excited triplet state scavenger (naphthalene) proved that this absorption spectrum belonged to the cation. 

Pulse radiolysis is used also for preparation of excited states of dienes and polyenes. This is done by irradiation of the diene/polyene in toluene solution. The radiolysis of toluene yield high concentration of molecules in the triplet excited state of the solute. Wilbrandt and coworkers61 pulse-radiolysed 1 mM solution of al I -lrans-1,3,5-heptatriene in toluene solution and observed the absorption spectra of the triplet state of the heptatriene with a maximum at 315 nm. The same group62 produced and measured the absorption spectra of several isomeric retinals in their lowest excited triplet state by pulse irradiation of their dilute solution in Ar-saturated benzene containing 10 2 M naphthalene. Nakabayashi and coworkers63 prepared the lowest triplet states of 1,3-cyclohexadiene,... 

A third important reaction of aromatic radical-cations is carbon-carbon bond formation with a further aromatic substrate. This reaction is limited to the oxidation in acetonitrile of substrates with electrondonating substituents. Radical-cations from benzene, naphthalene and anthracene form a-complexes but do not form a a-bonded reaction intermediate. Tlie dimerization reaction has been investigated both by pulse-radiolysis [22] in water and by electrochemical methods [27] in acetoni-... 

By contrast, in the pulse radiolysis of naphthalene and xenon mixtures in the gaseous phase, the triplet state of naphthalene was produced almost instantaneously (< 0.5 /isec)109. This was attributed to energy transfer by direct impact of sub-excitation electrons. 

Sens, (pulse radiolysis of benzene energy transfer to naphthalene, anthracene, benzophenone, benzil) Determination of energy transfer efficiencies 369... 

Intramolecular hole transfer has also been investigated [34, 35], a spectacular example being that observed using the 10-bond dyad 11(10) [35]. In this system, the naphthalene (Np) and dimethoxynaphthalene (DMN) chromophores are rigidly separated, approximately 12 A apart. Pulse radiolysis of a cyclohexane solution of 11(10) at room temperature generated a statistical mixture of the two radical cations, +Np-B-DMN and Np-B-DMN+. Exergonic hole transfer from the Np radical cation to DMN in this mixture was found to occur on a subnanosecond time scale, thereby confirming that TB-mediated HT is extremely rapid, even over 10 bonds ... 

Pulse radiolysis of solutions of naphthalene and benzophenone (12) in various non-polar and polar liquids has shown the following. The naphthalene triplet was observed in benzene and in cyclohexane, and was not detected in ether, tetrahydrofuran, or methanol. The benzophenone triplet was observed in benzene, but appeared to have a small or negligible yield in cyclohexane and in tetrahydrofuran. 

The nanosecond pulse radiolysis technique has been described (8, 14). Carbon tetrachloride was purified as follows Matheson Research grade CC14 was dried over anhydrous potassium carbonate for several days, and subsequently distilled, discarding initial and final fractions. However, untreated research grade CCLj gave identical results to that treated as above. Zone refined naphthalene, anthracene, biphenyl, and N,N,N, N -tetramethyl-paraphenylenediamine (TMPD) were used pyrene, 1 2 benzanthracene were recrystallized from absolute alcohol, and aniline was purified as described in an earlier paper (6). Normal hexane, cyclohexane, 3-methylpentane, benzene, and toluene were Matheson research grade methanol and ethyl alcohol were analytical grade. 

For solutions of naphthalene in cyclohexane the yield of triplet states of naphthalene, the intensity of monomer and excimer fluorescence, and the yield of singlet state naphthalene have been measured as a function of naphthalene concentration by pulse radiolysis methods. The influence of a number of electron scavengers on these yields has been determined... 

The first resonance Raman spectra of /3-carotene in its triplet state were obtained in 1979, using excitation at 531 nm which is located near the main T<—T absorption transition at 515 nm. The triplet state was accumulated by pulse radiolysis, using naphthalene as a sensitizer, and this was one of the first examples of time-resolved resonance Raman spectroscopy applied to a molecular excited state (Dallinger et al.,... 

As noted in Section 3, the lifetimes of arylalkene radical cations in the absence of added nucleophiles or alkenes are frequently determined by their reaction with excess neutral alkene in solution to generate an adduct radical cation that ultimately gives the 1,2-diarylcyclobutane or substituted naphthalene products described above. Rate constants for the addition of the radical cation to its neutral precursor have been measured recently for both styrene and diarylethylene radical cations using either flash photolysis or pulse radiolysis methods. - ... 

The reactivity of solvated electrons generated by pulse radiolysis was studied with different micellar solutions [138-143]. A study of the solvation of electrons in inverted AOT micelles in iso-octane has shown that the electrons are rapidly solvated if the molar ratio H2O/AOT is 60, and are not solvated at all if H20/A0T 5 [138]. Electron solvation in normal and inverted micelles was also studied in femto- and picosecond ranges [139]. The solvated electrons react with halogenenaphthalenes in CTAB micelles [140], with the vesicle-forming surfactant in dioctadecyldimethyl-aminonium bromide vesicles [141], with naphthalene in SDS micelles [142], with... 

Pb(CH3)4 vapor has been used to fill Geiger counters [170 to 174], and was suggested for use in liquid ionization chambers [175]. Short-lived transients are generated by pulse radiolysis of Pb(CH3)4 dosed with naphthalene and toluene, which can be employed for time-resolved dosimetry of low-energy X-rays [176]. 

Hunt, J.W. and Thomas, J.K., Pulse radiolysis studies of the formation of triplet excited states in cyclohexane solutions of naphthalene and anthracene,/. Chem. Phys., 46, 2954,1967. 

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