| We designed and set up an experimental equipment for studying the infrared emission of chemical reactions employing Step-Scan time-resolved Fourier Transform Infrared Spectroscopy(TR-FTIR). With TR-FTIR, first, the photodissociation dynamics of alky nitrites (n-C4H9ONO, (CH3)2C3H5ONO, (CH3)3CONO) and fluorotoluene (ortho, para) at 355 nm and 266 nm; second, the reaction dynamics of C2 with O2 and CH with alcohol (CH3OH, C2H5OH, C6H11OH) in the gas phase have been studied in this dissertation. The main results are the followings.1). Photodissociation dynamics of alky nitrites (n-C4H9ONO, (CH3)2C3H5ONO, (CH3)3CONO) at 355nm: Photodissociation dynamics study of n-C4H9ONO, (CH3)2C3H5ONO and (CH3)3CONO by means of time-resolved Fourier transform infrared (TR-FTIR) emission spectroscopy. The obtained TR-FTIR emission spectra of the nascent NO fragments produced in the 355-nm laser photolysis of the three alkyl nitrite species The nascent NO fragments of n-C4H9ONO and (CH3)2C3H5ONO showed an almost identical rotational temperature and vibrational distributions of NO. In addition, a close resemblance between the two species was also found in the measured temporal profiles of the IR emission of NO and the recorded UV absorption spectra. The experimental results are consistent with our ab initio calculations using the time-dependent density functional theory at the B3LYP/6-311G(d,p) level, which indicate that the substitution of one of the twoγ-H atoms in n-C4H9ONO with a methyl group to form (CH3)2C3H5ONO has only a minor effect on the photodissociation dynamics of the two molecules. By analyzing the observed TR-FTIR emission spectra of the NO fragments produced in the 355-nm laser photolysis of (CH3)3CONO), we obtained the rotational temperature and the relative vibrational distribution of NO. In addition, an inversion was found to occur in such a vibrational distribution. With the aid of n-C4H9ONO and (CH3)2C3H5ONO studies, we determined the v = v* - 1 relationship between the vibrational quantum number of NO corresponding to its maximum vibrational distribution(v) and the vibrational quantum numbers(0→v*) relating to the overtone transitions of the parent molecule. 2). Photodissociation dynamics of o-fluorotoluene at 266 nm: Following the photodissociation of o-fluorotoluene at 266 nm, rotationally resolved emission spectra of HF(1≤v≤3)in the spectral region of 2500-4500 cm-1 are detected with a step-scan TR-FTIR, HF(1≤v≤3) shows nearly Boltzmann-type rotational distributions corresponding to a temperature 785±42K, a short extrapolation from data leads to a nascent rotational temperature of 1053±105K with an average rotational energy of 8.7±0.5KJ/mol The observed vibrational distribution of (v= 1): (v = 2) : (v = 3 ) = (0.73) : (0.21) : (0.06) corresponds to a vibrational temperature of 3040±46K, An average vibrational energy of 29.27 kJ/mol is derived based on the observed population of HF(1≤v≤3) and estimates of the population of HF (v = 0) by extrapolation. Experiments performed on p-fluorotoluene yielded similar results with an average rotational energy of 8.6±0.5 kJ/mol and vibrational energy of 26.77 kJ/mol for HF. The observed vibrational distribution of (v = 1): (v = 2): (v = 3 ) = (0.77): (0.18): (0.05) corresponds to a vibrational temperature of 2635±40K.3). For the reaction of C2 + O2, primary vibrationally excited products CO2 and CO were observed for the first time. The elementary reaction channels were identified and reaction mechanism was suggested as follows: C2 + O2→C2O2→CO2 + C and C2 + O2→C2O2→2CO.4). For the reaction of CH with alcohol (CH3OH, C2H5OH, C6H11OH), primary vibrationally excited products CO were observed in the all reactions for the first time. The most feasible reaction pathway should be CH radical attacking on OH group in alcohol, followed by the insertion of CH into the O-H bond. The elementary reaction channels were: CH + R-OH→R+ CO + H2... |
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