Sodium oxide, excited, from

Photolysis reactions often are associated with oxidation because the latter category of reactions frequently can be initiated by light. The photooxidation of phenothiazines with the formation of N- and S-oxides is typical. But photolysis reactions are not restricted to oxidation. In the case of sodium nitroprusside, it is believed that degradation results from loss of the nitro-ligand from the molecule, followed by electronic rearrangement and hydration. Photo-induced reactions are common in steroids [36] an example is the formation of 2-benzoylcholestan-3-one following irradiation of cholest-2-en-3-ol benzoate. Photoadditions of water and of alcohols to the electronically excited state of steroids have also been observed [37],... 

A still more complicated reaction is the chemiluminescent oxidation of sodium hydrogen sulfide, cysteine, and gluthathione by oxygen in the presence of heavy metal catalysts, especially copper ions 60>. When copper is used in the form of the tetrammin complex Cu(NH3) +, the chemiluminescence is due to excited-singlet oxygen when the catalyst is copper flavin mononucleotide (Cu—FMN), additional emission occurs from excited flavin mononucleotide. From absorption spectroscopic measurements J. Stauff and F. Nimmerfall60> concluded that the first reaction step consists in the addition of oxygen to the copper complex ... 

As mentioned, electronically excited states are both easily reduced (since an electron can be accepted in the half vacant HOMO) and easily oxidized (since an electron can be donated from the half-hlled LUMO) under much milder conditions than the corresponding ground states. As an example, reducing the ground state of benzophenone requires the use of a highly reactive reductant, such as sodium metal... 

Red-emitting Y202S Eu3+ phosphors were developed especially for excitation with cathode rays [5.345], [5.346]. Production generally starts from mixed rare-earth oxides, which are fired with sodium carbonate and sulfur. The polysulfide formed... 

Excited singlet oxygen generated in situ by oxidising hydrogen peroxide with sodium hypochlorite, produces results chemically indistinguishable from photo-sensitised auto-oxidation of olefins [70]. 

An analysis of the time course of luminescence emission following selective laser excitation has enabled the forward and reverse rate constants to be obtained for the equilibrium between the Eu" complex of 1,2-diaminocyclohexanetetraacetate, [Eu(DCTA)], and iminodiacetate, IMDA, to form the ternary complex [Eu(DCTA)(IMDA)] . Some other systems in which chemical interconversion processes occur at rates much greater than, or much slower than, the reciprocal excited-state lifetime of the Eu" -containing species were also examined. A matrix isolation e.s.r. study has appeared of the photoreduction of the formato-complex of Eu " in a formic acid-sodium formate buffer. A three-step cyclic scheme has been suggested to explain the observations, namely photoreduction of by Eu, radical alternation from H to C02 , and oxidation of CO2 by Eu ". ... 

A communication and full paper tell of the efficient photoreduction of 4-chlorobiphenyl to biphenyl by excitation of 9,10-dihydro-lO-methylacridine (163) or acriflavine (164) in aqueous acetonitrile containing sodium borohydride. A variety of alkyl halides, benzyl halides and chlorobenzenes were also reduced. The reaction proceeds by electron transfer from the excited state of the dihydroacridine to the chloroarene, chloride loss and hydrogen atom donation to the arene radical. Thus photoreduction of the arene is coupled with oxidation of the dihydroacridine to the acridinium salt the latter is reduced back to the dihydroacridine by the borohydride. 

In flame emission spectrometry, a hot flame is required for the analysis of a large number of elements, and the nitrous oxide-acetylene flame is used. The oxy-acetylene flame has a high burning velocity and cannot be used with a conventional premix burner. The nitrous oxide-acetylene flame can, however, be used with a premix burner. Because of its high temperatures, a special, thick, stainless steel burner head must be used to prevent it from melting. A cool air-propane or similar flame is preferred for the flame emission spectrometry of the easily excited elements sodium and potassium because of decreased ionization of these elements. 

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