Spectrum of acetylene

Herman, M., Abbouti-Temsamani, M., Lemaitre, D., and Vander Auwera, J. (1991), The Fourier-Transform Vibrational Spectrum of Acetylene in the Visible Range, Chem. Phys. Lett. 185, 220. 

Scherer, G. J., Lehmann, K. K., and Klemperer, W. (1983), The High-Resolution Visible Overtone Spectrum of Acetylene, J. Chem. Phys. 78, 2817. 

The vibrogram analysis [108] based on the dispersion fluorescence spectrum of acetylene by Solina et al. [125] reveals a recurrence around 50 fs from 0 to 12,000 cm"1, which is similar to the one in the previous analysis. However, an important recurrence appears at 70 fs at higher energies from 4000 to 16,000 cm 1, which is caused either by anharmonic period lengthening or by a transition to a slower regime at higher energies. 

Fig. 4. (A) Spectrum of acetylene chemisorbed on nickel (B) after treatment with Hs. ...

It has been shown that acetylene when submitted to a high frequency electric discharge yields some diacetylene 75. The action of ultra-violet radiation of wavelength 2,378-2,100 A on acetylene also produced diacetylene, and Cherton considered that the primary step must be the photodissociation of acetylene to C2H and H. At sufficient pressure the absorption spectrum of acetylene shows a continuous absorption in this region superimposed in the band structure. This gives an upper limit of 121 kcal to D(HC C-H). 

Bryant, G. W., Eggers, D. R, and Watts, R. O., High resolution infrared spectrum of acetylene tetramers, Chem. Phys. Lett. 151,309-314 (1988). 

The vertical electronic spectrum of acetylene shows many similarities with that of the isoelectronic molecule HCN. Both are linear molecules in their electronic ground states, but their lowest-valence excited states are bent. Photoexcitation of acetylene in the near-UV (190-240 nm) induces a electron promotion, resulting in population of the planar, trans bent A A state ( S in the linear limit) [312], The A A —transition is dominated by long progressions involving v 3 (the excited state trans bending mode), as would be expected on Franck-Condon grounds. The A—X... 

Fig. 3. Relative ion intensities as a function of pressure in the high-pressure mass spectrum of acetylene.

Fig. 6.22. Optoacoustic overtone absorption spectrum of acetylene around y = 15 600 cm corresponding to the excitation of a local mode by five quantum vibrations [6.56]...

FIGURE 18.2 This vibrational spectrum of acetylene, C2H2, shows intensity variations that are due to the effect of the nuclear wavefunctions symmetry on the degeneracies of the overall wavefunction of the molecule. This is one of the few direct consequences of nuclear wavefunctions in chemistry. Source L. W. Richards, J. Chem. Ed., 1996, 43 645. 

The rovibrational spectrum of acetylene, H—C C—H, shows intensity variations consistent with expected nuclear degeneracies. Would you expect D—C=C—H to show similar intensity variations Why or why not ... 

The interpretation of nmr spectra in isotropic media is considerably simplified by the well known rule that the indirect spin—spin-coupling between so called equivalent nuclei (nuclei with identical chemical shift) does not lead to an observable line splitting. This rule is no longer true for the direct nuclear coupling. The proton resonance spectrum of acetylene, for instance, is split up in a doublet by the dipolar coupling between the two equivalent protons. The spectrum of partially aligned benzene exhibits about fifty lines. 

The Raman spectrum of acetylene was the subject of many investigations [18,49,173-177] concentrating on the rotational spectrum and the Raman active fundamentals Vi, V2, and V4. Through recording of the second-order rovibrational Raman spectrum of C2H2, the anharmonicity constant X22, which had been predicted by Strey and Mills [178], could be determined by analyzing the combination band which overlaps with 21 2 [49]. The... 

I-Y Wang, A Weber. High resolution Raman spectroscopy of gases with laser sources The spectrum of acetylene. Indian J Pure Appl Phys 16 358-369, 1978. 

Given the center of symmetry and the statement that this is a simple molecule, a reference spectrum of acetylene should be consulted. When this is done, the answer is found to be acetylene. 

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