The Electronic Structure of the (CH3)2N Radical and the Pyrolysis Mechanism of Dimethylnitrosamine: A HeI Photoelectron Spectroscopic Study
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A continuous dimethylamino (CH3)2N ± (DMA) radical beam is produced in situ by the pyrolysis of dimethylnitrosamine (CH3)2NNO at 850 (0.5 ° C) in a double-heater inlet system on a double-chamber UPS machine-II which was built specifically to detect transient species. The HeI photoelectron spectrum (PES) of the (CH3)2N radical is recorded for the first time. To assign the PES bands of the (CH3)2N radical, the improved density functional theory (DFT) calculation based on the Amsterdam density functional (ADF) program package has been carried out according to C2v symmetry for the ground state of the neutral (CH3)2N radical and the equilibrium geometries of several ionic states of the cationic species. A sharp peak with the lowest ionization energy at 9.01 ± 0.02 eV comes from electron ionization of the HOMO(2b1) of the (CH3)2N radical, corresponding to the ionization of the (CH3)2N (X 2B1) to (CH3)2N+(X 1A1). The second band with vibration spacing 1980 ± 60 cm-1 comes from electron ionization of 1a2 orbital which is a strongly bound state for the (CH3)2N radical, corresponding to ionization of (CH3)2N (X 2B1) to the 3B1 state of (CH3)2N+ cation. The PES bands of the NO molecule clearly appears in the PE spectrum of the products pyrolyzed of the compound. The pyrolysis mechanism of the (CH3)2NNO compound is shown as follows:Keywords:
Radical ion
Quinoline
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The recent photoelectron spectroscopy (PES) paper by Wang, et al. confirms our earlier photoionization mass spectrometric (PIMS) determination of the adiabatic ionization energy of NO3. The PES results are also consistent with our conclusion that the ground-state neutral geometry for NO3 is D3h. However, the PE spectrum shows a second band (and higher bands) with a vertical I.E. (ionization energy) at 13.18 eV that was absent in our photoionization efficiency spectrum. A possible reason for the apparent discrepancy is suggested and further differences between the two studies are discussed.
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Bacteroides fragilis was analysed by pyrolysis gas chromatography (PGC). The influence of temperature rise time, pyrolysis temperature and pyrolysis time on the yield of volatile organic pyrolysis products was studied. The use of short pyrolysis time (8 msec) and a high pyrolysis end temperature (1300 degrees C) was found to provide a high yield. In consecutive analyses of the test organism, under the pyrolysis conditions indicated, the standard deviation of the total yield of volatile organic products was +/- 7%. The pyrolysis technique described suggests that few secondary reactions of the pyrolysis fragments occur.
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Abstract The gas-phase X-ray photoelectron spectra (with MgKα radiation) were observed on acetonitrile, propionitrile, acrylonitrile and fumaronitrile. The ionization potentials were determined for all valence-electron levels of the above molecules by using the data derived from the observed valence-electron bands of X-ray photoelectron spectra and the reported data of ultraviolet photoelectron spectroscopy. It is shown that there is a linear relation between the observed ionization potential (IP) and the CNDO/2 orbital energy (ε): IP=0.61(−ε)+3.2[eV], for σ-orbitals; IP=0.38(−ε)+6.0[eV], for π-orbitals. The observed binding energies of the C ls levels were analyzed by means of the electrostatic potential model and the charge densities calculated by CNDO/2 method. Discussion is given also on the shake-up satellite of core-electron peak.
CNDO/2
Ultraviolet photoelectron spectroscopy
Propionitrile
Valence electron
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A comparison of values of the ionization potential of NO2 derived from direct electron impact, from dissociative ionization of CH3NO2, and from the ultraviolet spectrum of NO2, show large discrepancies. There is reason to believe that three different electronic states are involved. The ionization potential of N2O as measured by electron impact is in good agreement with spectroscopic data. The appearance potential of O+ ion from N2O gives D(NN–O)=39.7 kcal/M, in excellent agreement with the thermochemical value of 39.49 kcal/M.
Ultraviolet
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Pyrolysis oil
Alkane
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This article presents the results of an experimental study of waste paper pyrolysis in tubular furnace pyrolysis equipment. Pyrolysis of waste paper has been conducted in different pyrolysis temperatures and heating rates to investigate the product distribution and yields of pyrolysis products. The pyrolysis oil was characterized by elemental analysis and various chromatographic and spectroscopic techniques, which are HPLC, 1H NMR, FTIR, and UV. The results of spectroscopic and chromatographic analysis show that there are four main different compounds in bio-oil: anhydrosugars, carboxyl compounds, carbonyl compounds and aromatic compounds.
Characterization
Pyrolysis oil
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