C2H2, inside

Lehwald and Ibach (7) investigated ethyne adsorption at 150 K on a stepped Ni surface [5 (111) x (110)]. They found a unique spectrum, with strong bands at 2220 and 350 cm"1, starting from either C2H2 or C2D2. This is clearly from a C2 species with essentially a triple bond, probably located along the inside of the steps. By the remarkably low temperature of 180 K, the C2 species decomposed further to give surface carbon (520 cm"1) and H atoms (690 cm"1). 

Fig. 6.8-5 shows part of a spectrum of C2H2 (6 = 1.177 cm ). A is obtained from this spectrum. The resulting sample temperature is T = 309 K, a value which is to be expected for a sample in a gas cell inside the closed. sample compartment of an IR spectrometer. 

From mass spectrometry studies Curzon (1984) reports that the reduction of CO, inside the vacuum chamber, leads to the formation of CH4 (and consequently of CH3, CH2 and CH). The results indicate that the CH4 (and also H2) arises from the reduction of the CO (and also H2O, which reacts with CO). That is another way to explain the formation of hydrides with rare earth thin films. The adsorption of CsHg, C2H2 and CH4 on clean polycrystalline Dy films at 295 K has been studied by Cemy and Smutek (1990). The experiments suggest that at low doses, the gases are completely dissociated into C and H atoms. The bonding of these atoms to Dy is assumed to be equivalent to that which... 

The yield of this procedure seems to depend on the quality of the calcium carbide used. TTie purity of the calcium carbide may be estimated ftom the amount of ethyne produced upon hydrolysis of a sample with dilute HCl. For example, pure CaC2 (64 mg, 1 mmol) should afford 22.4 mT, of C2H2. Tlie checker manipulated the CaC2 inside a glove box. 

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