Strube et al.: Dissociation of CF2HCl and CF2Cl2
9485
gas surplus ͑16 000 Pa curve͒ dissociation can be completely
suppressed during the ir laser pulse. Since no absorbers are
lost, the total absorbed energy was increased by a factor of
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tributed by
–
v v
energy pooling, yielding the dissociative
action shown. A marked effect of –T processes can be
v
ruled out due to the increased heat capacity ͑by 40 times͒.
The effect of a radiative heating of the CF2 product, as it
may occur at the wavelength chosen for IRMPD of CF2HCl,
could not be clarified. The lack of such a product resonance
at the laser wavelength chosen is not the only reason, why
results quantitatively different from CF2HCl were obtained
for the parent molecule CF2Cl2. Typical of CF2Cl2 is also the
small primary production of CF2, the respective molecular
elimination channel is only of minor importance at high flu-
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marked, as was shown in Fig. 4͑a͒. It can only be the result
of secondary reactions.
Still controversial is the contribution of the secondary
dissociation of the major primary product CF2Cl, recombin-
ing to our major stable product 1.2-C2F4Cl2. In Ref. 8 sec-
ondary dissociation of a fraction of 20% was estimated at a
fluence of 6 J/cm2 under molecular beam conditions. Accord-
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present conditions an intense
–
v v
exchange with the hot
parent molecules renders the fragment highly vibrationally
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energy partitioning in the IRMPD process. In any case, this
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