Acetylene spectrum

The 1500 to 2000 A bands are diffuse and have been assigned to the lBu-transition by Foo and Innes (367). The bands 1403 to 1519 A probably belong to a n state. Below 1403 A several transitions have been found with vibrational structure. Most bands belong to the Rydberg series. Demoulin and Jungen (281) have made theoretical assignments of the acetylene spectrum. 

The XPS survey spectrum of a 75 nm thick film of plasma polymerized acetylene that was deposited onto a polished steel substrate is shown in Fig. 18 [22]. This film consisted mostly of carbon and a small amount of oxygen. Thus, the main peaks in the spectrum were attributed to C(ls) electrons near 284.6 eV and 0(ls) electrons near 533.2 eV. Additional weak peaks due to X-ray-induced O(KVV) and C(KLL) Auger electrons were also observed. High-resolution C(ls) and 0(ls) spectra are shown in Fig. 19. The C(ls) peak was highly symmetric. 

Fig. 18. XPS survey spectrum of a plasma-polymerized acetylene film with a thickness of 75 nm that was deposited onto a polished steel substrate. Reproduced by ptermission of John Wiley and Sons from Ref. [22].

Positive SIMS spectra obtained from plasma polymerized acetylene films on polished steel substrates after reaction with the model rubber compound for times between zero and 65 min are shown in Fig. 44. The positive spectrum obtained after zero reaction time was characteristic of an as-deposited film of plasma polymerized acetylene. However, as reaction time increased, new peaks appeared in the positive SIMS spectrum, including m/z = 59, 64, and 182. The peaks at 59 and 64 were attributed to Co+ and Zn, respectively, while the peak at 182 was assigned to NH,J(C6Hn)2, a fragment from the DCBS accelerator. The peak at 59 was much stronger than that at 64 for a reaction time of 15 min. However,... 

Similarly, a common feature in the mass spectrum of thiirene oxides is the high abundance of the substituted acetylene ion (e.g. [PhC CPh]7) formed by elimination of sulfur monoxide. In fact, this ion constitutes the base peak in the spectrum of 18a whereas the molecular ion has a rather insignificant intensity (0.25% I of M+)91. 

Fig. 4.6. The CARS spectrum collapse of acetylene Q-branch with increase of gas...

Smirnov V. V., Fabelinskii V. I. Pressure-induced change of the shape and width of the coherent anti-Stokes light scattering spectrum of the V2 oscillations of acetylene. JETP Lett. 27, 123-5 (1978) [Pis ma ZhETP, 27, 131-4 (1978)]. 

Application to Ethylene Radiolysis. The predominant ions in the mass spectrum of ethylene (1) are ethylene, vinyl, and acetylene ions, which together account for over 85% of the total ionization. A total of 38% of all ions are C2H4+, and since kF(ethylene) = 25.9 e.v./ion pair, the parent ion should be produced with a yield of at least 1.5 ions/100 e.v. absorbed in ethylene. Similar calculations for the probable yields of the other major ions lead to estimates of 0.96 vinyl ions/100 e.v. and 0.94 acetylene ions/100 e.v. Successive dissociations are relatively unimportant in ethylene. 

Fraction 4 (P.E./CHjClj, 1 1) was a bright red solution the T1 NMR spectrum of which indicated a mixture of two acetylenic constituents (A and B) which were separated by preparative TLC on 1 mm silica gel plates. The red band (A), when left in soln for 15 hr at r.t., lost its color. The Tl NMR spectrum of the decolored soln was identical with the spectrum of compound B. Comparison of the physical data (1H NMR and MS) of the two compounds with the spectral data reported for the dithiophene (A) (10) and the thiophene (B)... 

Figure 7. Acetylene Region of Infrared Spectrum of IP-600 as a Function of Time at 183°C.

Scheme 14 Top Plausible catalytic cycle as supported by deuterium labeling. Bottom ESI mass spectrum of a reaction mixture aliquot diluted 5000-fold in methanol from the hydrogen-mediated coupling of gaseous acetylene to an a-ketoester (Ar = p-N02Ph)...

The infrared spectrum in the OH region for the adsorption of methyl acetylene is completely analogous to that for acetylene. The spectrum of CH3—C=C—D, however, introduces some new features (65). Initially, an OH band appears in time, however, an OD band appears. By analogy with base catalyzed reactions of acetylene (71) we believe the methyl... 

The initial appearance of an OH band followed by the later appearance of an OD band agrees with this scheme. Also in agreement with this scheme, we find that adsorbed allene yields the same spectrum as methyl acetylene... 

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