For the initially formed C3H2 collision complexes of molecular beam experiments ab initio calculations are presented. Resolving energetics and properties of these intermediates is essential for the understanding of the reaction of C(3P) with C2H2 to form interstellar cyclic and linear isomers of C3H. Computed reaction energies agree with results from molecular beam experiments. The combination of crossed molecular beam experiments and ab initio calculations allows us to identify two reaction channels for the carbon–hydrogen exchange and to explain astronomical observations of a higher c-C3H to 1-C3H ratio in dark clouds as compared to hotter envelopes of carbon stars.
REFERENCES
1.
2.
P.
Thaddeus
, J. M.
Vrtilek
, and C. A.
Gottlieb
, Astrophys. J. Lett.
299
, L63
(1985
).3.
J.
Cernicharo
, C.
Kahane
, M.
Guelin
, and J.
Gomez-Gonzalez
, Astron. Astrophys.
189
, L1
(1988
).4.
S.
Yamamoto
, S.
Saito
, M.
Ohishi
, H.
Suzuki
, S.
Ishikawa
, N.
Kaifu
, and A.
Murakami
, Astrophys. J. Lett.
322
, L55
(1987
).5.
T. J.
Millar
, C. M.
Leung
, and E.
Herbst
, Astron. Astrophys.
183
, 109
(1987
).6.
7.
D. C.
Clary
, N.
Haider
, D.
Husain
, and M.
Kabir
, Astrophys. J. Lett.
422
, 416
(1994
).8.
9.
R. I. Kaiser, C. Ochsenfeld, M. Head-Gordon, Y. T. Lee, and A. G. Suits, J. Chem. Phys. (in press).
10.
R. I.
Kaiser
, C.
Ochsenfeld
, M.
Head-Gordon
, Y. T.
Lee
, and A. G.
Suits
, Science
274
, 1508
(1996
).11.
N. J. Turro, Modern Molecular Photochemistry (University Science, Mill Valley, 1991).
12.
13.
W. J.
Hehre
, J. A.
Pople
, W. A.
Lathan
, L.
Radom
, E.
Wasserman
, and Z. R.
Wasserman
, J. Am. Chem. Soc.
98
, 4378
(1976
).14.
J. W.
Kenney
III, J.
Simons
, G. D.
Purvis
, and R. J.
Bartlett
, J. Am. Chem. Soc.
100
, 6930
(1978
).15.
C. E.
Dykstra
, C. A.
Parsons
, and C. L.
Oates
, J. Am. Chem. Soc.
101
, 1962
(1979
).16.
17.
18.
J. M.
Bofill
, J.
Farras
, S.
Olivella
, A.
Sole
, and J.
Vilarrasa
, J. Am. Chem. Soc.
110
, 1694
(1988
).19.
20.
21.
22.
23.
C. D.
Sherrill
, C. G.
Brandow
, W. D.
Allen
, and H. F.
Schaefer
, J. Am. Chem. Soc.
118
, 7158
(1996
).24.
G.
Maier
, H. P.
Reisenauer
, W.
Schwab
, P.
Carsky
, V.
Spirko
, B. A.
Hess
, Jr., and L. J.
Schaad
, J. Chem. Phys.
91
, 4763
(1989
).25.
26.
27.
K. Aoki, K. Hashimoto, and S. Ikuta, Astrophys. J. (submitted).
28.
29.
30.
31.
M.
Kanada
, S.
Yamamoto
, S.
Saito
, and Y.
Osamura
, J. Chem. Phys.
104
, 2192
(1996
).32.
33.
R. J. Bartlett and J. F. Stanton, in Reviews of Computational Chemistry, edited by K. B. Lipkowitz und D. B. Boyd (VCH, New York, 1990), Vol. 5, p. 65.
34.
ACES II, an ab initio program system written by J. F. Stanton, J. Gauss, J. D. Watts, W. J. Lauderdale, and R. J. Bartlett;
Quantum Theory Project (University of Florida, Gainesville, 1992);
for a detailed description, see
J. F.
Stanton
, J.
Gauss
, J. D.
Watts
, W. J.
Lauderdale
, and R. J.
Bartlett
, Int. J. Quantum Chem. Symp.
26
, 879
(1992
).35.
K.
Raghavachari
, G. W.
Trucks
, J. A.
Pople
, and M.
Head-Gordon
, Chem. Phys. Lett.
157
, 479
(1989
).36.
37.
38.
K. A.
Brueckner
, A. M.
Lockett
, and B.
Rotenberg
, Phys. Rev.
121
, 255
(1961
), and references therein.39.
40.
L. Z.
Stolarczyk
and H. J.
Monkhorst
, Int. J. Quantum Chem. Symp.
18
, 267
(1984
).41.
N. C.
Handy
, J. A.
Pople
, M.
Head-Gordon
, K.
Raghavachari
, and G. W.
Trucks
, Chem. Phys. Lett.
164
, 185
(1989
).42.
K.
Raghavachari
, J. A.
Pople
, E. S.
Replogle
, M.
Head-Gordon
, and N. C.
Handy
, Chem. Phys. Lett.
167
, 115
(1990
).43.
44.
45.
46.
G. D.
Purvis
, H.
Sekino
, and R. J.
Bartlett
, Coll. Czech. Chem. Commun.
53
, 2203
(1988
).47.
48.
49.
50.
51.
52.
N. A.
Burton
, Y.
Yamaguchi
, I. L.
Alberts
, and H. F.
Schaefer
, J. Chem. Phys.
95
, 7466
(1991
).53.
54.
55.
G. Herzberg, Molecular Spectra and Molecular Structure, reprint edition (Krieger, Malabar, 1991), Vol. III.
This content is only available via PDF.
© 1997 American Institute of Physics.
1997
American Institute of Physics
You do not currently have access to this content.