Author(s) |
Indulkar, Y. N.; Upadhyaya, H. P.; Kumar, A.; Waghmode, S. B.; Naik, P. D.
|
Photodissociation of 3-bromo-1,1,1-trifluoro-2-propanol (BTFP) has been investigated at 193 nm, employing
the laser photolysis laser-induced fluorescence technique. The nascent OH product was detected state selectively,
and the energy released into translation, rotation, and vibration of the photoproducts has been measured. OH
is produced mostly vibrationally cold, with a moderate rotational excitation, which is characterized by a
rotational temperature of 640 ± 140 K. However, an appreciable amount of the available energy of 36.1 kcal
mol-1 is released into translation of OH (15.1 kcal mol-1). OH product has no preference for a specific
spin-orbit state, P3/2 or
P1/2. However, between two Λ-doublet states,
P+
and P-, the OH product has a
preference for the former by a factor of 2. A mechanism of OH formation from BTFP on excitation at 193
nm is proposed, which involves first the direct C-Br bond dissociation from a repulsive state
(nBrσ*C-Br) as a primary process. The primary product,
F3C-CH(OH)-CH2, with sufficient internal energy undergoes
spontaneous C-OH bond dissociation, through a loose transition state. The formation rate of OH is calculated
to be 5.8 × 106 s-1 using Rice-Ramsperger-Kassel-Marcus unimolecular rate theory. Experimental results
have been supported by theoretical calculations, and energies of various low-energy dissociation channels of
the primary product, F3C-CH(OH)-CH2, have been calculated.
|