Ni. Butkovskaya et Dw. Setser, UNIMOLECULAR DECOMPOSITION OF CHEMICALLY ACTIVATED DEUTERO-SUBSTITUTED ETHANOL MOLECULES STUDIED BY INFRARED CHEMILUMINESCENCE FROM H2O, HOD, AND D2O, The Journal of chemical physics, 105(18), 1996, pp. 8064-8074
Vibrationally excited H2O, HOD, and D2O molecules formed by unimolecul
ar elimination from deutero-substituted ethanol molecules C2H5OH, C2H
5OD, CH2DCH2OH*, and CH2DCH2OD* with an excitation energy of about 10
0 kcal mol(-1) were observed by infrared chemiluminescence in the 2400
-3900 cm(-1) range. The activated ethanol molecules were produced via
the successive reactions H+CH2ICH2OH-->HI+CH2CH2OH and H+CH2CH2OH-->CH
3CH2OH in a fast flow reactor that was observed with a Fourier transf
orm spectrometer. The vibrational distributions of the H2O, HOD, and D
2O molecules were determined by computer simulation of the experimenta
l spectra; the distributions decline with increasing vibrational energ
y giving [f(v)]=0.15 and [f(v)]=0.14 for H2O and HOD from the decompos
ition of C2H5OH and C2H5OD*, respectively. The vibrational energy in
the bending mode of H2O is comparable to the energy in the stretching
modes. Comparison with the statistical vibrational distributions shows
a substantial overpopulation of the bending levels and a preferential
excitation of one O-H or O-D stretching quantum in HOD from C2H5OD or
CH2DCH2OH, respectively, i.e., in the newly formed bond. Kinetic isot
ope effects of [H2O]/[HOD]=3.6+/-0.8 and [HOD]/[D2O]=3.1+/-0.8 were fo
und for the two elimination pathways of CH2DCH2OH and CH2DCH2OD*, res
pectively, which agree with calculated RRKM values of k(H2O)/k(HOD) =
3.2 and k(HOD)/k(D2O) = 2.7. (C) 1996 American Institute of Physics.