THE INFRARED SPECTRA OF THE HALOGEN ISOCYANATE AND THIOCYANATE VAPOR MOLECULES
Fourier transform infrared spectroscopy has been used to investigate the IR spectra of the XNCO (X = Cl, Br, I, CN), the XSCN (X = Cl, Br, I) and the NCNCS vapor molecules from 4800 to 400 cm-1.Vibrational frequencies have been determined for e
The gas phase chemistry that occurs after the photolysis of ClNCO at 248 nm is characterized by the action of two excited intermediates, N(2D) and N2(A).Each of these reacts with ClNCO to generate NCO(A 2Σ+), and blue emission from the NCO(A 2Σ+ -> X 2Π) transition is observed.The time profile of the NCO emission consists of two distinct components, a fast component arising from the N(2D) + ClNCO reaction and a slow component arising from the N2(A) + ClNCO reaction.The N(2D) is an initial photofragment and the N2(A ) is generated in the N(2D) + ClNCO reaction.The value of the rate constant for N(2D) + ClNCO is determined to be 7.0 +/- 0.8 * 10-11 cm3 s-1.The rate constant measured from the decay of the NCO emission in a previous work (2.1 +/- 0.2 * 10-11 cm3 s-1 ) is assigned to the N2(A) + ClNCO reaction.
Kinetics of the reactions of NCO radicals with NO and NH3
The rate constants for the reaction of NCO (X2∏) radicals with NO and NH3 were measured at 20 Torr total pressure in temperature ranges of 290-1098 K and 295-882 K, respectively, using C1NCO excimer laser photolysis for NCO radical formation in combination with laser-induced fluorescence detection of NCO. In the temperature range investigated the NCO + NO reaction exhibits a negative temperature dependence which is described by the following three parameter Arrhenius equation: (Equation Presented) with E0 in units of kJ/mol. For the NCO + NH3 reaction the measurements exhibit a positive temperature dependence over the temperature range investigated with a slight upwards curvature. A modified three parameters Arrhenius fit provides a good description of the experimental data: (Equation Presented) with E0 in units of kJ/mol. In addition, the rate constant of the NCO + NH3 reaction was found to be pressure independent in the range 10-193 Torr at 295 K. VCH Verlagsgesellschaft mbH, 1997.
Becker,Kurtenbach,Schmidt,Wiesen
p. 128 - 133
(2007/10/03)
Isolierung und Photoisomerisierung von einfach substituierten Nitriloxiden
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Maier, Guenther,Teles, Joaquim Henrique
p. 152 - 153
(2007/10/02)
Photodissociation of chlorine isocyanate
Gaseous ClNCO exhibits a continuous ultraviolet absorption feature peaked near 250 nm.Photolysis of this compound at 249 nm produces bright blue emission identified as the A2Σ+ -> X2Π transition in NCO.The excited NCO arises from a collisional process in which N(2D) atoms, produced directly by the photodissociation, react with the parent ClNCO.The rate constant for this process is k = (2.1 +/- 0.2)*10-11 cm3 s-1. From production of N(2D) by the 249 nm photolysis, the heat of formation of gaseous ClNCO is inferred to be ΔHf(ClNCO) >= 52.9 kcal mol-1. ClNCO is metastable with respect to the ground electronic states of NCl and CO by 8.2 kcal mol-1.
Bell, D. D.,Coombe, R. D.
p. 1317 - 1322
(2007/10/02)
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