Fourier transform microwave spectrum of HCCC15N and global analysis of the high resolution infrared and rotational spectra up to 1700cm−1

High-resolution infrared spectroscopy of diacetylene below 1000 cm−1

“…The resonance between v 4 = 1 and v 6 = 2, present in HCCC 15 N, is analogous to that between v 3 = 1 and v 7 = 2 which has been considered for diacetylene: Ref. [30] gives W 466 = 43.03 cm −1 and W 466J = −1.84 MHz. According to Aliev and Watson [31], it is possible to estimate the order of magnitude of an Hamiltonian coefficient C mn using…”

“…B v and D v for the unobserved v 7 = 2 state) or from the most recent ab initio anharmonic force field calculations [17,18]. The only exception was the centrifugal correction parameters W 377J , whose value was estimated empirically from the results of a global ro-vibrational analysis performed for the isoelectronic carbon chain HCCC 15 N [30]. The resonance between v 4 = 1 and v 6 = 2, present in HCCC 15 N, is analogous to that between v 3 = 1 and v 7 = 2 which has been considered for diacetylene: Ref.…”

“…From Ref. [30] we derived a scaled W 377J value of -1.41 MHz (see Discussion for the details), which was constrained in the final analysis. The spectroscopic constants determined by the least-squares fit are collected in Table 3.…”

Rotational and High-resolution Infrared Spectrum of HC 3 N: Global Ro-vibrational Analysis and Improved Line Catalog for Astrophysical Observations

“…Other possible couplings are: the quartic anharmonic interaction between the ( 5 , 6 , 7 ) and ( 5 + 1, 6 − 2, 7 + 1) states generated by H40 , plus the H31 Coriolis-type resonances that couple the states ( 6 , 7 ) and ( 6 + 1, 7 − 2), and ( 5 , 6 , 7 ) and ( 5 + 1, 6 − 1, 7 − 1). These interactions were found to be important in the global fit of the infrared and rotational spectra of the HCCC 15 N isotopologue (Fayt et al 2004a(Fayt et al , 2008. We have tested these terms in the HC 3 N analysis, but they produce only minor effects and the corresponding coefficients were poorly determined.…”

“…Because of the numerous perturbations that affect the rotation-vibration spectrum of HC 3 N, a global analysis of the laboratory data including both pure-rotational and high-resolution IR measurements is necessary in order to derive a compact set of effective spectroscopic parameters without ambiguities, and to achieve spectral prediction of high accuracy. To the best of our knowledge, unlike for the HCCC 15 N species (Fayt et al 2004a(Fayt et al , 2008, there is no published global analysis for the main isotopologue.…”