Electron Scattering From Molecules: Applications Of The Schwinger Multichannel Method To E--co And E--c2h 4 Collisions

Abstract

To illustrate our recent efforts to obtain electronic excitation cross sections of molecules by electron impact, we present in this paper results for the X 1Σ a 3Π and A 1Π transitions of CO obtained with the Schwinger multichannel method. Our results are in good agreement with other theoretical calculations, although not so good when compared with experiments. We also discuss the importance of inclusion of polarization effects to obtain electronic excitation cross sections of some molecules through an example using the C2H4 molecule, which has a triplet state with a low-energy threshold. Finally, we present a very simple rule to estimate integral electronic excitation cross sections using the differential cross section (DCS) at 900, which can be useful to experimentalists using apparatus with difficulties to measure the DCS's at angles around 0 and 180 degrees. We show its efficiency for the present electronic excitation of the C2H4 molecule by electron impact. © 2007 IOP Publishing Ltd.881Garscadden, A., (1992) Z. Phys., 24 (2), pp. 97-99Boudaïffa, B., Cloutier, P., Hunting, D., Huels, M.A., Sanche, L., (2000) Science, 287 (5458), pp. 1658-1660Da Costa, R.F., Da Paixão, F.J., Map, L., (2004) J. Phys. B: At. Mol. Phys., 37 (6), pp. 129-L135Da Costa, R.F., Da Paixão, F.J., Map, L., (2005) J. Phys. B: At. Mol. Phys., 38 (24), pp. 4363-4378Da Costa, R.F., Map, L., (2006) Int. J. Quantum Chem., 106 (13), pp. 2664-2676Nonum Da Costa, R.F., Map, L., (2007) Phys. Rev., 75, p. 022705Sun, Q., Winstead, C., McKoy, V., Lima, M.A.P., (1992) J. Chem. Phys., 96 (5), pp. 3531-3535Rescigno, T.N., Schneider, B.I., (1992) Phys. Rev., 45 (5), pp. 2894-2902Takatsuka, K., McKoy, V., (1981) Phys. Rev., 24 (5), pp. 2473-2480Takatsuka, K., McKoy, V., (1984) Phys. Rev., 30 (4), pp. 1734-1740Chaudhuri, P., Varella Do, T.M.N., Carvalho, C.R.C., Map, L., (2004) Nucl. Instrum. Methods Phys. Res., 221, pp. 69-75Chaudhuri, P., Varella Do, T.M.N., Carvalho, C.R.C., Map, L., (2004) Phys. Rev., 69, p. 042703Lane, N.F., (1980) Rev. Mod. Phys., 52 (1), pp. 29-119Sun, Q.Y., Winstead, C., McKoy, V., (1992) Phys. Rev., 46 (11), pp. 6987-6994Morgan, L.A., Tennyson, J., (1993) J. Phys. B: At. Mol. Opt. Phys., 26 (15), pp. 2429-2441Lee, M.-T., MacHado, A.M., Fujimoto, M.M., MacHado, L.E., Brescansin, L.M., (1996) J. Phys. B: At. Mol. Opt. Phys., 29 (18), pp. 4285-4301Furlong, J.M., Newell, W.R., (1996) J. Phys. B: At. Mol. Opt. Phys., 29 (2), pp. 331-338Leclair, L.R., Trajmar, S., (1996) J. Phys. B: At. Mol. Opt. Phys., 29 (22), pp. 5543-5566Zetner, P.W., Kanik, I., Trajmar, S., (1998) J. Phys. B: At. Mol. Opt. Phys., 31 (10), pp. 2395-2413Trajmar, S., Szabo, A., Ostlund, N.S., (1989) Modern Quantum Chemistry: Introduction to Advanced Electronic Structure Theory, pp. 194-197Da Costa, R.F., Bettega, M.H.F., Lima, M.A.P., Van Veen, E.H., (1976) Chem. Phys. Lett., 41 (3), p. 540Asmis, K.R., Allan, M., (1997) J. Chem. Phys., 106 (17), pp. 7044-7046Da Costa, R.F., Bettega, M.H.F., Lima, M.A.P., Da Costa, R.F., Bettega, M.H.F., Lima, M.A.P.