We report electron-scattering cross sections determined for 2-methyl–2-butene [(H3C)HC = C(CH3)2] and 2,3-dimethyl–2-butene [(H3C)2C = C(CH3)2] molecules. Absolute grand-total cross sections (TCSs) were measured for incident electron energies in the 0.5–300 eV range, using a linear electron-transmission technique. The experimental TCS energy dependences for the both targets appear to be very similar with respect to the shape. In each TCS curve, three features are discernible: the resonant-like structure located around 2.6–2.7 eV, the broad distinct enhancement peaking near 8.5 eV, and a weak hump in the vicinity of 24 eV. Theoretical integral elastic (ECS) and ionization (ICS) cross sections were computed up to 3 keV by means of the additivity rule (AR) approximation and the binary-encounter-Bethe method, respectively. Their sums, (ECS+ICS), are in a reasonable agreement with the respective measured TCSs. To examine the effect of methylation of hydrogen sides in the ethylene [H2C = CH2] molecule on the TCS, we compared the TCS energy curves for the sequence of methylated ethylenes: propene [H2C = CH(CH3)], 2-methylpropene [H2C = C(CH3)2], 2-methyl–2-butene [(H3C)HC = C(CH3)2], and 2,3-dimethyl–2-butene [(H3C)2C = C(CH3)2], measured in the same laboratory. Moreover, the isomeric effect is also discussed for the C5H10 and C6H12 compounds.
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14 August 2015
Research Article|
August 14 2015
Electron collisions with methyl-substituted ethylenes: Cross section measurements and calculations for 2-methyl–2-butene and 2,3-dimethyl–2-butene
J. Chem. Phys. 143, 064306 (2015)
Article history
Received:
May 28 2015
Accepted:
July 21 2015
Citation
Czesław SzmytkowskiSylwia StefanowskaMateusz ZawadzkiElżbieta Ptasińska-DengaPaweł Możejko; Electron collisions with methyl-substituted ethylenes: Cross section measurements and calculations for 2-methyl–2-butene and 2,3-dimethyl–2-butene. J. Chem. Phys. 14 August 2015; 143 (6): 064306. https://doi.org/10.1063/1.4927703
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