Photolysis of ammonia at 2062 A. in the presence of propane

Groth, W.; Schurath, U.; Schindler, R. N.

doi:10.1021/j100857a034

Cited by 38 publications

(29 citation statements)

References 3 publications

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“…The final product balance gave an upper limit of -0.2 for kdlk,. Similarly, irradiation of the NHs-propane system has yielded a value of kd/kc = 0.21 f 0.7 for the recombination of NH2 and propyl radicals (mainly i-propyl) [20]. In similar experiments, using isobutane instead of propane, an upper limit of kd/k, <0.5 was established in this laboratory for the reaction between NH2 and t-C4H9 radicals [21].…”

Section: Discussionmentioning

confidence: 95%

Absolute rate constants for the reactions between amino and alkyl radicals at 298 K

Demissy

Lesclaux

1982

Int J of Chemical Kinetics

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The absolute rate constants for the reactions of NH2 radicals with ethyl, isopropyl, and t-butyl radicals have been measured at 298 K, using a flash photolysis-laser resonance absorption method. Radicals were generated by flashing ammonia in the presence of an olefin.A new measurement of the NH2 extinction coefficient and oscillator strength at 597.73 nm was performed. The decay curves were simulated by adjusting the rate constants of both the reaction of NH2 with the alkyl radical and the mutual interactions of alkyl radicals. The results are k(NH2 + alkyl) = 2.5 (f0.5), 2.0 (f0.41, and 2.5 (f0.5) X 1Olo A4-l.s-l for ethyl, isopropyl, and t-butyl radicals, respectively. The best simulations were obtained when taking k(alky1 + alkyl) = 1.2,0.6, and 0.65 X 10IOM-'-s-l for ethyl, isopropyl, and t -butyl radicals, respectively, in good agreement with literature values.

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Section: Discussionmentioning

confidence: 95%

Absolute rate constants for the reactions between amino and alkyl radicals at 298 K

Demissy

Lesclaux

1982

Int J of Chemical Kinetics

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“…Since NH 3 absorbs m u c h more strongly than CO at w a v e l e n g h t s longer than 184.9 nm (Thompson et al 1963 NH2CO (Spall & Steacie, 1957) (Groth et al, 1968). D i s p r o p o r t i o n a t i o n of NH2CO (7) does not appear to be a m a j o r pathway for the formation of HNC0 because the yield of a m m o n i u m cyanate exceeds that of formamide by 2.5-10 times.…”

Section: Biuret Urea and Oxamide Have Been Suggested As P O S S I B mentioning

confidence: 99%

Ultraviolet-gas phase and -photocatalytic synthesis from CO and NH3

et al. 1975

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The major photoproduct obtained on irradiation of gaseous NH3 and CO mixtures is ammonium cyanate; lesser amounts of urea, biurea, biuret semi-carbazide, formamide and cyanide were observed. The formation of the major gas phase photolysis product may be rationalized by the following reaction sequence: (see article). Urea is probably formed from NH4NCO in a thermal reaction while formamide may result from the disproportionation of NH2CO. Photocatalytic syntheses of 14C-urea, -formamide, and -formadehyde are effected by irradiation of 14CO and NH3 in the presence of Vycor, silica gel, or volcanic ash shale surfaces. These syntheses are catalyzed by ultraviolet wavelengths longer than those absorbed by the gaseous reactants. The syntheses are also effected when the surface material is first irradiated in the presence of CO followed by a dark incubation with NH3. Apparently, the initiating step is a light dependent formation of a reactive form of CO on the surface. A discussion is given on the possible contribution of these reactions to the abiotic synthesis of organic nitrogen compounds on Mars, on the primitive Earth and in interstellar space.

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“…The dissociation process occurs with near unity quantum yield. 6 Leifson 1 first measured theÃ state absorption spectrum of ammonia in the range of 45 455-67 000 cm −1 . It consists of a single long progression in ν 2 , the excited state out-ofplane mode.…”

Section: Introductionmentioning

confidence: 99%

A full-dimensional coupled-surface study of the photodissociation dynamics of ammonia using the multiconfiguration time-dependent Hartree method

Giri

Chapman

Sanz-Sanz

et al. 2011

The Journal of Chemical Physics

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Full-dimensional quantum mechanical computations are carried out to investigate the photodissociation dynamics of Ã state NH(3) and ND(3) using the multiconfiguration time-dependent Hartree (MCTDH) method with recently developed coupled ab initio potential energy surfaces (PESs) [Z. H. Li, R. Valero, and D. G. Truhlar, Theor. Chim. Acc. 118, 9 (2007)]. To use the MCTDH method efficiently the PESs are represented as based on the high-dimensional model representation. The Ã ← X̃ absorption spectra for both isotopomers were calculated for the zeroth vibrational state of the ground electronic state. With a view to treating larger systems, Jacobi coordinates are used. Computations on the coupled PES are carried out for two-, three-, five-, and six-dimensional model systems to understand the validity of reduced-dimensional calculations. In addition to the fully coupled calculations, the effect of nonadiabatic coupling on absorption spectra is shown by propagating the initial wavepacket only in the Ã electronic state. The calculated absorption spectra are shown to be in good agreement with available theoretical and experimental observations. Comparisons with calculations using Radau and valence coordinates show the effect of including the symmetry of the system explicitly. Finally, branching ratios for loss of a hydrogen atom via the two available channels are calculated. These predict that the nonadiabatic product increases with the dimension of the calculations and confirm the importance of the full-dimensional calculations.

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Photolysis of ammonia at 2062 A. in the presence of propane

Cited by 38 publications

References 3 publications

Absolute rate constants for the reactions between amino and alkyl radicals at 298 K

Absolute rate constants for the reactions between amino and alkyl radicals at 298 K

Ultraviolet-gas phase and -photocatalytic synthesis from CO and NH3

A full-dimensional coupled-surface study of the photodissociation dynamics of ammonia using the multiconfiguration time-dependent Hartree method

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