Photodissociation Dynamics of the Ethoxy Radical (C₂H₅O)

Abstract

Photodissociation of the ethoxy (C 2 H 5 O) radical is investigated using photofragment translational spectroscopy. The ethoxy radical is generated by photodetachment of C 2 H 5 O -and subsequently dissociated by photon absorption in the range of 270-220 nm; no dissociation is seen at higher wavelengths. The photofragment yield (PFY) spectrum is structureless but exhibits abrupt increases in intensity at 260 and 225 nm. The product mass distribution shows that C 2 H 5 O dissociates into the vinyl radical (C 2 H 3 ) and H 2 O throughout the entire absorption band. We propose that these products are formed by isomerization and dissociation on electronically excited surfaces rather than by internal conversion to the ground state. The translational energy P(E T ) distributions for this channel are largely insensitive to photon energy. However, at the two highest photon energies (5.51 and 5.96 eV), a new feature appears at E T e 0.3 eV, which is assigned as production of an excited state of C 2 H 3 .

Radiative and non-radiative decay of selected vibronic levels of the B state of alkoxy radicals

“…Physically this is because the larger (and more branched) alkyl groups tend to stabilize the highly polar C-O bond in the e B B state, compared to the much less polar bond in the e X X state. This finding is consistent with the recent observations by Choi et al [16] that dissociation does not occur from the e B B state of ethoxy as it does from the corresponding state in methoxy.…”

Photodissociation Dynamics of the Ethoxy Radical Investigated by Photofragment Coincidence Imaging

“…Dissociation photon energies (hν diss ) ranged from 5.17 to 5.96 eV, over which a largely unstructured photofragment yield spectrum and coincidence photofragment distributions were previously acquired. 25 Photodissociation was also attempted at 3.91284 eV, corresponding to the energy of the sharp V ) 4 r 0 band of the C-O stretching mode in the B 2 A′ r X 2 A′′ transition. 24 Photofragments from the second laser pulse continue another 2 m along the beam path before hitting the time and position sensitive detector.…”

Probing chemical dynamics with negative ions

“…155,156 The PFY spectrum measured by Choi et al 164 showed only a higher energy, unstructured band starting around 4.7 eV. 155,156 The PFY spectrum measured by Choi et al 164 showed only a higher energy, unstructured band starting around 4.7 eV.…”