English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The 205-230 nm photodissociation of vibrationally excited CO2 at temperatures up to 1800 K was studied using Resonance Enhanced Multiphoton Ionization (REMPI) and time-sliced Velocity Map Imaging (VMI). CO2 molecules seeded in He were heated in an SiC tube attached to a pulsed valve and supersonically expanded to create a molecular beam of rotationally cooled but vibrationally hot CO2. Photodissociation was observed from vibrationally excited CO2 with internal energies up to about 20 000 cm(-1), and CO(X(1)Σ(+)), O((3)P), and O((1)D) products were detected by REMPI. The large enhancement in the absorption cross section with increasing CO2 vibrational excitation made this investigation feasible. The internal energies of heated CO2 molecules that absorbed 230 nm radiation were estimated from the kinetic energy release (KER) distributions of CO(X(1)Σ(+)) products in v″ = 0. At 230 nm, CO2 needs to have at least 4000 cm(-1) of rovibrational energy to absorb the UV radiation and produce CO(X(1)Σ(+)) + O((3)P). CO2 internal energies in excess of 16 000 cm(-1) were confirmed by observing O((1)D) products. It is likely that initial absorption from levels with high bending excitation accesses both the A(1)B2 and B(1)A2 states, explaining the nearly isotropic angular distributions of the products. CO(X(1)Σ(+)) product internal energies were estimated from REMPI spectroscopy, and the KER distributions of the CO(X(1)Σ(+)), O((3)P), and O((1)D) products were obtained by VMI. The CO product internal energy distributions change with increasing CO2 temperature, suggesting that more than one dynamical pathway is involved when the internal energy of CO2 (and the corresponding available energy) increases. The KER distributions of O((1)D) and O((3)P) show broad internal energy distributions in the CO(X(1)Σ(+)) cofragment, extending up to the maximum allowed by energy but peaking at low KER values. Although not all the observations can be explained at this time, with the aid of available theoretical studies of CO2 VUV photodissociation and O + CO recombination, it is proposed that following UV absorption, the two lowest lying triplet states, a(3)B2 and b(3)A2, and the ground electronic state are involved in the dynamical pathways that lead to product formation.

journal of chemical physics online/the journal of chemical physics/journal of chemical physics

Temperature dependence of the photodissociation of CO2from high vibrational levels: 205-230 nm imaging studies of CO(X1Σ+) and O(3P,1D) products