jz9b01811_si_001.pdf (1.45 MB)
Observation of the Carbon Elimination Channel in Vacuum Ultraviolet Photodissociation of OCS
journal contribution
posted on 2019-08-07, 20:05 authored by Wentao Chen, Liang Zhang, Daofu Yuan, Yao Chang, Shengrui Yu, Siwen Wang, Tao Wang, Bin Jiang, Kaijun Yuan, Xueming Yang, Xingan WangThe textbook mechanism
for OCS photodissociation mainly involves
the CO + S or CS + O product channel via a single bond fission. However,
a third dissociation channel concerning the cleavage of both C–S
and C–O bonds yielding SO + C products, though thermodynamically
allowed, has never been verified experimentally to date. By using
a tunable vacuum ultraviolet laser light and time-sliced velocity
map ion imaging technique, we have clearly observed the SO(X3Σ–) + C(3PJ=0) products as the vacuum ultraviolet laser photon energy
gradually exceeds its thermodynamic threshold. The corresponding SO(X3Σ–) coproducts are highly vibrationally
excited and show varying angular distributions from isotropic to anisotropic
as the excitation photon energy increases. Theoretical analysis suggests
that a fast nonadiabatic pathway plays a dominant role in the formation
of the anisotropic SO products. That isotropic products arise as the
excitation photon energies approach the thermodynamic threshold can
be reasonably explained by the “roaming mechanism”.
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nonadiabatic pathwaytime-sliced velocity map ion imaging techniquelaser photon energyexcitation photon energy increasesCarbon Elimination Channelthresholdtunable vacuumtextbook mechanismdissociation channelC productsCOVacuum Ultraviolet Photodissociationexcitation photon energies approachO product channelanisotropiclaser lightTheoretical analysisOCS photodissociationbond fission
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