Vibrational Spectroscopic Database on Acetylene, X̃ 1Σg+ (12C2H2, C212D2, and C213H2)

Abstract

Information on the vibrational energy states in acetylene (12C2H2, C212D2, and C213H2) is gathered: spectroscopic constants (vibrational frequencies and anharmonicities, vibration-rotation interaction parameters), observed vibrational energy states and complete sets of predicted vibrational energies and predicted principal rotational constants Bv for states of C212H2, C212D2, and C213H2 up to 15000, 10000, and 12000 cm−1, respectively. Statistical parameters (partition functions and integrated number of states) deduced from these predicted spectroscopic data are provided for the three isotopomers. The equilibrium geometrical structure is determined to be re(CH)=106.138(35) pm and re(CC)=120.292(13) pm from constants available for C212H2, C212D2, C213H2, and C212HD.

Vibrational-Rotational Spectra of Normal Acetylene and Doubly Deuterated Acetylene: Experimental and Computational Studies

“…From the experimental results, there are excellent agreements of the bond length of normal acetylene with previous literature studies. For instance, in recent research by Herman et al, 11 bond length of C-H and C-C in C 2 H 2 have been reported as 105.756(52) pm and 120.830 (20) pm respectively. While in this study we found the C-H and C-C bond length as 1.08653±0.0057 Å and 1.18983±0.0010 Å respectively.…”

“…The infra-red spectroscopy has been widely utilized for probing the vibrational and rotational energy levels of molecules by chemists for structural elucidations. The vibrationalrotational spectra of acetylene molecule both in the ground electronic and excited states in the last decades were extensively investigated using spectroscopic methods [10][11][12] . The annex 1 of Herman et al, 10 provides an abundant reference of most literature papers of the spectroscopic data on acetylene in the ground electronic state.…”

“…The IR inactive modes include the v 1 symmetric stretch, the v 2 C-C stretch and the doubly degenerate v 4 trans-bend. However, other non-fundamental bands often appear in the infrared spectra of acetylene and are term combination bands which have also been a subject of investigation and the results are widely reported in the literature 11,14 Several spectroscopic techniques have been applied to record the vibration-rotation spectra of acetylene. For instance, Keppler et al, 15 used spectrograph recordings, spectro to analyzed the vibrational spectra of acetylene while Kostyk and Welsh 16 and Bermejo et al, 17 have used conventional and stimulated Raman spectroscopy respectively for this purpose.…”

Formation of coherent rotational wavepackets in small molecule-helium clusters using impulsive alignment

“…Geometry optimisations carried out for the complex and isolated C 2 H 2 with basis set sizes up to sextuple zeta quality show that complexation with He changes the geometry of C 2 H 2 at most by 0.0001Å. The C 2 H 2 unit was consequently fixed at its experimental ground state expectation geometry, 88 r 0 (CC) = 1.20830Å and r 0 (CH) = 1.05756Å.…”

“…4 corresponds to particular frequency contributions of C 2 H 2 to the rotational wavepackets. The observed lines were recorded at a pump laser intensity of 2.5×10 11 Wcm −2 and coincide with the beat frequencies of free C 2 H 2 at 6b + 4nb, where b is the C 2 H 2 rotational constant † (b = 1.1767 cm −1 ) 88 and n = 0, 1, 2, 3. The first line at 6b frequency is equivalent to the J ′ = 2 ← J ′′ = 0 transition, with successive lines at 10b, 14b, 18b.…”