10
J. Chem. Phys., Vol. 115, No. 1, 1 July 2001
Shu et al.
As pointed above, two dynamical features are observed.
In addition to the above observed channel, three addi-
tional channels H formation, H2 formation, and OH forma-
tion, have also been observed in the O(1D)ϩC3H6 reaction.
Final analysis of all reaction channels will be reported in a
future full paper.
The nature of these two features is a more interesting issue.
According to the above analysis, the two features are likely
to come from the following two channels: HCOHϩC2H4 and
H2COϩC2H4. From the energetic diagram, the available en-
ergy for the H2COϩC2H4 channel is about 136 kcal/mol,
while that for the HCOHϩC2H4 channel is about 84 kcal/
mol. From the CM kinetic energy distributions shown in Fig.
3, the energetic limit of the faster component of the two
contributions is about 130 kcal/mol, which agrees quite well
with the available energy of the H2COϩC2H4 channel.
Therefore, it is reasonable to assign the faster contribution to
the H2COϩC2H4 channel. The nature of the slower contribu-
tion observed at mass 31 is, however, more ambiguous. Ob-
viously this slower contribution is quite different from the
faster one because of its distinctive angular distribution.
From the simulation, the energetic limit of the slower contri-
bution is about 40 kcal/mol. However, there is a rather large
uncertainty in this limit due to the correlations in simulating
the two features. Nevertheless, this limit appears to be sig-
nificantly lower than the available energy of the
HCOHϩC2H4 channel. Therefore, it is somewhat question-
able to assign this slower feature to the HCOHϩC2H4 chan-
nel. It is still possible that this channel is from the
HCOHϩC2H4 pathway since the mismatch between the en-
ergetic limit and the available energy could be due to the fact
that available energy is distributed into the internal degrees
of freedom of the two molecular products. This feature could
also come from the other sources, such as excited product
channels of H2COϩC2H4 or even HCOHϩC2H4. Mention
that the adiabatic excitation energy for the first excited state
of H2CO is 80.7 kcal/mol,33 which leaves 55.6 kcal/mol of
available energy for the H2CO(S1)ϩC2H4 products. More
detailed theoretical study on this issue is desirable in order to
clarify this point.
The implications of an H2COϩC2H4 reaction is even
more interesting. From the energetic diagram, this reaction
channel should be a direct product from the oxetane complex
formed through the O(1D) insertion into the C–C bond
͑see Fig. 1͒. Therefore, we believe that the observation of
this channel is a clear experimental evidence of the O(1D)
atom insertion into a C-C bond, which is normally quite
difficult to achieve. From our previously studies of the
O(1D) reactions with small alkanes, O(1D) normally inserts
into a C–H bond, which is somewhat less difficult because
the H atom is lighter and that makes it easier to displace. It is
reasonable to believe that the insertion of O(1D) into the
C–C bond in cyclopropane is made easier due to the banana
type character of the C–C bond, in which the electronic
cloud of the C–C bond is more accessible than for normal
alkanes because of its banana shape. An interesting question
regarding this process is whether the breaking up of the C–C
and C–O bonds in the ‘‘hot’’ oxetane complex is simulta-
neous or one that is stepwise and involves a ring-opening
process. Our present calculations show that this reaction oc-
curs in one step with simultaneous rupture of two bonds in
the ring.
This work is supported by the Academia Sinica, the
National Science Council, and the China Petroleum
Company.
1 C.-L. Lin and W. B. Demore, J. Phys. Chem. 77, 863 ͑1972͒.
2 W. Tsang, Int. J. Chem. Kinet. 8, 193 ͑1976͒, and references therein.
3 R. I. Greenberg and J. Heicklen, Int. J. Chem. Kinet. 4, 417 ͑1972͒.
4 P. Casavecchia, R. J. Buss, S. J. Sibener, and Y. T. Lee, J. Chem. Phys.
73, 6351 ͑1990͒.
5 S. Satyapal, J. Park, R. Bersohn, and B. Katz, J. Chem. Phys. 91, 6873
͑1989͒.
6 A. C. Luntz, J. Chem. Phys. 73, 1143 ͑1980͒.
7 S. G. Cheskis, A. A. Iogansen , P. V. Kulakov, I. Y. Razuvaev, O. M.
Sarkissov, and A. A. Titov, Chem. Phys. Lett. 155, 37 ͑1989͒.
8 Y. Matsumi, K. Tonokura, Y. Inagaki, and M. Kawasaki, J. Phys. Chem.
97, 6816 ͑1993͒.
9 C. R. Park and J. R. Wiesenfeld, J. Chem. Phys. 95, 8166 ͑1991͒.
10 M. Brouard, S. Duxon, P. A. Enriquez, and J. P. Simons, J. Chem. Soc.,
Faraday Trans. 89, 1435 ͑1993͒; M. Brouard, S. P. Duxon, and J. P.
Simons, Isr. J. Chem. 34, 67 ͑1994͒.
11 R. D. van Zee and J. C. Stephenson, J. Chem. Phys. 102, 6946 ͑1995͒.
12 P. M. Aker, J. J. A. O’Brien, and J. J. Sloan, J. Chem. Phys. 84, 745
͑1986͒.
13 Y. Rudich, Y. Hurwitz, G. J. Frost, V. Vaida, and R. Naaman, J. Chem.
Phys. 99, 4500 ͑1993͒.
14 Y. Hurwitz, Y. Rudich, and R. Naaman, Chem. Phys. Lett. 215, 674
͑1993͒.
15 R. D. Van Zee, J. C. Stephenson, and M. P. Casassa, Chem. Phys. Lett.
223, 167 ͑1994͒.
16 T. Suzuki and E. Hirota, J. Chem. Phys. 98, 2387 ͑1993͒.
17 R. Schott, J. Schluter, and K. Kleinermanns, J. Chem. Phys. 102, 8371
͑1995͒.
18 J. Schluter, R. Schott, and K. Kleinermanns, Chem. Phys. Lett. 213, 262
͑1993͒.
19 W. Hack and H. Thiesemann, J. Phys. Chem. 99, 17364 ͑1995͒.
20 R. A. Brownsword, M. Hillenkamp, P. Schmiechen, H.-R. Volpp, and H.
P. Upadhyaya, J. Phys. Chem. 102, 4438 ͑1998͒.
21 G. Brasseur, S. Solomon, Aeronomy of the Middle Atmosphere ͑Reidel,
Boston, 1984͒.
22 J. R. Wiesenfeld, Acc. Chem. Res. 15, 110 ͑1982͒.
23 J. J. Lin, Y. T. Lee, and X. Yang, J. Chem. Phys. 109, 2975 ͑1998͒.
24 J. J. Lin, S. Harich, Y. T. Lee, and X. Yang, J. Chem. Phys. 110, 10821
͑1999͒.
25 J. J. Lin, J. Shu, Y. T. Lee, and X. Yang, J. Chem. Phys. 113, 5287 ͑2000͒.
26 J. Shu, J. J. Lin, Y. T. Lee, and X. Yang, J. Chem. Phys. 114, 4 ͑2001͒.
27 J. Shu, J. J. Lin, Y. T. Lee, and X. Yang, J. Am. Chem. Soc. 123, 322
͑2001͒.
28 A. D. Becke, J. Chem. Phys. 98, 5648 ͑1993͒; C. Lee, W. Yang, and R. G.
Parr, Phys. Rev. B 37, 785 ͑1988͒.
29 G. D. Purvis, R. J. Bartlett, J. Chem. Phys. 76, 1910 ͑1982͒; G. E. Scu-
seria, C. L. Janssen, H. F. Schaefer III, ibid. 89, 7382 ͑1988͒; G. E.
Scuseria, H. F. Schaefer III, ibid. 90, 3700 ͑1989͒; ͑d͒ J. A. Pople, M.
Head-Gordon, K. Raghavachari, ibid. 87, 5968 ͑1987͒.
30 C. W. Bauschlicher, Jr., H. Partridge, J. Chem. Phys. 103, 1788 ͑1995͒; A.
M. Mebel, K. Morokuma, M. C. Lin, ibid. 103, 7414 ͑1995͒.
31
GAUSSIAN 98, Revision A.7, M. J. Frisch et al. ͑Gaussian, Inc., Pittsburgh,
PA, 1998͒.
32 MOLPRO is a package of ab initio programs written by H.-J. Werner and
¨
P. J. Knowles with contributions from J. Almlof et al.
33 A. K. Shah and D. C. Moule, Spectrochim. Acta, Part A 34A, 749 ͑1978͒;
P. Jensen and P. R. Bunker, J. Mol. Spectrosc. 94, 114 ͑1982͒.
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