The absolute grand -total cross section (TCS) for electron scattering from pyridine, C 5 H 5 N, molecules has been measured at impact energies from 0.6 to 300 eV in the linear electrontransmission experiment. The obtained TCS energy dependence appears to be typical for targets of high electric dipole moment; the cross section generally decreases with rising energy, except for the 3-20 eV range, where a broad enhancement peaked near 8.5 eV is clearly visible. Below 10 eV, some weak structures which can be attributed to resonant scattering processes are also discernible.The present TCS energy dependence is compared with TCS experimental data obtained recently for energies above 13 eV by Traoré Dubuis et al. [26]. The TCS for pyridine has been confronted with TCS for benzene to search how the replacement of the CH group in the benzene ring with the nitrogen atom influences the electron scattering process. In addition, for pyridine and its halogenated derivatives: 2-chloropyridine [2-C 5 H 4 ClN] and 2-bromopyridine [2-C 5 H 4 BrN], integral elastic (ECS) and ionization (ICS) cross sections have been calculated at intermediate and high electron-impact energies within semiempirical approaches. For pyridine the sum of ECS and ICS is in reasonable agreement with the measured TCS above 40 eV.

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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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