Nitrogen, collisional deactivation

Flash photolysis studies<22) have indicated singlet methylene to be produced from the diazomethane-excited singlet upon loss of nitrogen followed by collisional deactivation to the triplet, the ground state multiplicity for this molecule. 

The photochemical decompositions of perfluoroazomethane - and per-fluoroazoethane closely resemble those of the parent azohydrocarbons. Thus perfluoroazomethane when irradiated in the near ultraviolet, decomposes to nitrogen and perfluoroethane via a primary dissociation step in which trifluoro-methyl radicals are formed. Quantum yields of about 0.25 in the gas phase at room temperature - may be the result of collisional deactivation of excited perfluoroazomethane molecules. 

A second new component is needed because phosphorescence mcasurcmcnis are usually performed at liquid nitrogen temperature in a rigid medium lu minimize collisional deactivation of the long-lived triplet state. Usually, a Dewar fla.sk with quartz windows, as shown in Figure I. i-I3. is a pan of a phosphorimeter. At the temperature u.sed. the analyte exists as a solute in a glass or solid solvent. A common solvent for this purpose is a mixture of diethylelher. pentane, and ethanol. 

Matrix-isolated NH, ND, and molecules formed by photolysis of normal and isotopically substituted HN3 in solid nitrogen or argon (T = 4 to 20 K) were identified by their fundamental vibrations and isotopic shifts observed in the IR spectrum. Since the observed IR frequencies correspond reasonably well with the gas-phase values for the electronic ground state and spin-conservation rules, on the other hand, require NH to be initially produced in an upper singlet state, a collisional deactivation in the matrix has been suspected. The following wavenumbers (in cm" T=15 K) were assigned to the fundamental vibrations in the electronic ground state X ... 

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