PM3, AM1, MNDO and MINDO3 semi-empirical IR spectra simulations for compounds of interest for Titan's chemistry: diazomethane, methyl azide, methyl isocyanide, diacetylene and triacetylene.
Four semi-empirical methods (PM3, AM1, MNDO and MINDO3) have been tested to find the best auxiliary tool for the gas chromatography/Fourier transform IR spectroscopy/mass spectrometry (GC/FTIR/MS) identification of five compounds of interest for Titan's atmospheric chemistry as test compounds: diacetylene, triacetylene, diazomethane, methyl azide, methyl isocyanide. Of the four methods, MINDO3 can be considered as the most appropriate method to facilitate the identification of such and similar compounds, since (1) the simulated IR spectra best match the experimental spectra for four compounds of five studied; and (2) MINDO3 provides the best linearity between the calculated and experimental frequencies (correlation coefficient of 0.995; a scaling factor of 0.84 can be applied to afford better correspondence between the calculated and experimental wavenumbers). None of the semi-empirical methods tested is able to predict (even approximately) infrared band intensities, and therefore a spectral intensity pattern.
Basiuk
V A
VA
Laboratorio de Química de Plasmas y Estudios Planertarios, Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Mexico, DF. basiuk@nuclecu.unam.mx
Navarro-González
R
R
Benilan
Y
Y
Raulin
F
F
D000114:Acetylene / Q000737:chemistry*; D001272:Atmosphere; D001386:Azides / Q000737:chemistry*; D003978:Diazomethane / Q000737:chemistry*; D005118:Extraterrestrial Environment; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D008962:Models, Theoretical; D009570:Nitriles / Q000737:chemistry*; D018539:Saturn; D012984:Software; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013057:Spectrum Analysis / Q000379:methods*; D013223:Statistics as Topic
D001386:Azides; D009570:Nitriles; C008462:methylisonitrile; D003978:Diazomethane; D000114:Acetylene