The high-resolution infrared spectrum of isoxazole vapor between 800 and 1700cm−1

Hegelund, F.; Larsen, R. Wugt; Nicolaisen, F.M.; Palmer, Michael H.

doi:10.1016/j.jms.2004.09.010

Cited by 22 publications

(55 citation statements)

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“…The pair of MP2 data (with each basis set) is marginally poorer again, but all five procedures give enough correlation with experiment to be acceptable. In general these results are more extended than previous theoretical studies of molecular properties for thiazole [22][23][24][25][26], but several of the previous numerical values are also close to experiment.…”

Section: Discussionsupporting

confidence: 75%

“…Molecular properties from these MW studies, such as dipole moments [17], 14 N quadrupole coupling constants [18], and nonlocal contributions of the diamagnetic susceptibility component perpendicular to the ring [19], are known from these MW studies. These properties are compared with our ground state structural results, and with previous theoretical calculated values [22][23][24][25][26] in Appendix A. These ground state theoretical results complete the study of the electronic structure of thiazole, and give a measure of the reliability of the present ground state wave-function for the excited state study.…”

Section: Molecular Structuresupporting

confidence: 52%

“…The absolute photoabsorption crosssection was obtained from the Beer-Lambert law, I t = I 0 exp (nrl), where I t is the intensity of the transmitted radiation after passing through the sample, I 0 is the incident intensity, n is the gas number density, r is the photoabsorption cross-section and l is the length of the gas column. The sample (Aldrich) had no additional infrared bands to those reported in the literature [26]; the UV spectral envelope in n-hexane showed broad maxima at 43,200 and 47800 cm À1 (5.356 and 5.926 eV, e 3400 and 2200, respectively) [27,28]. The wide scan VUV spectrum is shown in Fig.…”

Section: Experimental Apparatus and Proceduresmentioning

confidence: 99%

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The electronic states of thiazole studied by VUV absorption spectroscopy and ab initio configuration interaction methods

Palmer

2008

Chemical Physics

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The thiazole VUV absorption spectrum over the range 5-12 eV shows intense bands near 5.4, 6.0, 7-7.8, 8.2-8.8, 9.2-10.1 and 10.2-11.0 eV; there is marked vibrational structure in the 7.5-8.5 and 10.2-11 eV regions. A number of Rydberg states have been identified, largely from IE 1 , but also tentative values for ones from IE 2 and IE 4 . Electronic excitation energies for valence and Rydberg-type states have been computed using ab initio multi-reference multi-root CI methods, and these have been compared with the VUV envelope. Calculated energies for low-lying Rydberg states are close to those expected, and there is generally a good correlation between the theoretical intensities and calculated density of states, with the experimental envelope. The CI studies used a triple zeta + polarization basis set, augmented by diffuse (Rydberg) orbitals. The lowest absorption bands are dominated by intense pp * (A 0 ) valence states, together with LP N p * and pr * states, which are relatively weak. The lowest Rydberg states arise from excitation of the occupied MOs in the sequential order p 4 < r 18 (LP N ) < p 3 < p 2 < r 17 (LP S ) this same order is determined by CI for ionisation in the UV-PES spectrum. Adiabatic structures of the r-and p-triplets, -cations and the p-anion have been compared with the ground state structure. The known phosphorescence of thiazole is from the 3 A triplet state (C 1 symmetry) where significant twisting of C 5 H and S to opposite sides of the mean plane occurs. Some theoretical molecular properties of thiazole are described, which give good agreement with microwave spectral data.

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Section: Discussionsupporting

confidence: 75%

Section: Molecular Structuresupporting

confidence: 52%

Section: Experimental Apparatus and Proceduresmentioning

confidence: 99%

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The electronic states of thiazole studied by VUV absorption spectroscopy and ab initio configuration interaction methods

Palmer

2008

Chemical Physics

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“…The vibrational modes and structural properties of the neutral isoxazole (and isoxazole-d 3 ) molecules have been determined from measurements of Raman and IR spectra in the vapour phase [6][7][8][9], aided by extensive theoretical calculations [8,[10][11][12]. In the most recent calculations [11,12], the IR and Raman spectra of isoxazole and isoxazole-d 3 have been reassigned with the aid of DFT theory [11] and a systematic study of the anharmonic vibrational frequencies has been carried out using both the B3LYP density functional and MP2 ab initio techniques [12].…”

Section: Introductionmentioning

confidence: 99%

Threshold photoelectron studies of isoxazole over the energy range 9.9–30eV

et al. 2010

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The threshold photoelectron spectrum of the isoxazole molecule, C 3 H 3 NO has been measured over the photon energy range 9.9eV to 30eV with the use of synchrotron radiation. In the 9.9-10.8 eV range, corresponding to photoionization from the highest occupied molecular orbital 3a"(π 3 ), seven well resolved vibrational series have been observed and their modes are tentatively assigned. A strong adiabatic ionization, with an energy of 11.132 ± 0.003eV corresponding to the 2a'' (π 2 ) band, has also been observed. This is followed by a single vibrational series of the v C-H stretching mode.Photoelectron bands in the energy region 13-30 eV have also been identified, some for the first time.

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“…Currently only few aromatic systems have been the subject of high resolution Fourier transform infrared spectroscopic studies. We mention here the benzene molecule [65][66][67] and its isotopomers [68][69][70] and heterocyclic systems, [71][72][73] in particular pyrimidine. [74] In addition, high resolution diode laser spectroscopy was carried out on fluoro- [75] and chlorobenzene [76] and there have been studies by isotope selective spectroscopy.…”

mentioning

confidence: 99%

High Resolution Rovibrational Spectroscopy of Chiral and Aromatic Compounds

Albert

Qüack

2007

ChemPhysChem

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The analysis of selected rovibrationally resolved infrared spectra of some relatively heavy and large polyatomic molecules is reviewed. A short historical summary of the development of high resolution interferometric Fourier transform infrared (FTIR) spectrometers is given and the possibilities of the currently most highly resolving FTIR spectrometer, which is commercially available in the Bruker IFS 125 series, are discussed. The computational tools necessary to analyse FTIR spectra are described briefly. As examples of rovibrational analysis the spectra of three selected molecules CHCl(2)F, CDBrClF, and pyridine (C(5)H(5)N) are discussed. The spectrum of CHCl(2)F, a fluorochlorohydrocarbon, is of interest for a better understanding of the chemistry of the Earth's atmosphere. CDBrClF is a chiral molecule and therefore the analysis of its rovibrational spectra provides the basis for carrying out further experiments towards the detection of molecular parity violation. The analysis of the pyridine FTIR spectra illustrates the potential of the new generation of FTIR spectrometers in the study of spectra and rovibrational dynamics of aromatic systems and molecules of potential biological interest.

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The high-resolution infrared spectrum of isoxazole vapor between 800 and 1700cm−1

Cited by 22 publications

References 4 publications

The electronic states of thiazole studied by VUV absorption spectroscopy and ab initio configuration interaction methods

The electronic states of thiazole studied by VUV absorption spectroscopy and ab initio configuration interaction methods

Threshold photoelectron studies of isoxazole over the energy range 9.9–30eV

High Resolution Rovibrational Spectroscopy of Chiral and Aromatic Compounds

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