Highly efficient production of neutral carbon atoms in the ultraviolet multiphoton fragmentation of aromatic molecules

Abstract

We report the observation of highly efficient production of neutral carbon atoms under moderate ultraviolet laser fluxes in the multiphoton fragmentation of several aromatic molecules. These processes are detected under collision-free conditions by resonance-enhanced three-photon MPI line resonances of carbon in its ground or first excited term. For the cases of CsFs and benzaldehyde, at least, it can be demonstrated that atomization precedes ionization of the parent molecule to a significant extent, indicating rapid dissociation of the neutral parent as an important atom formation channel entrance.

Photodissociation of dicarbon: How nature breaks an unusual multiple bond

“…Some of the excited C2 subsequently dissociates, while some C2 absorbs a second pump photon to produce C + 2 , allowing us to monitor and optimize the C2 production from its resonant two-photon ionization (R2PI) signal. The nascent carbon atoms are probed with a third laser by (2+1) resonanceenhanced multiphoton ionization (REMPI) (33). Carbon has three closely spaced spin-orbit components in the 3 PJ electronic ground state, J = |L + S | = 2, 1, and 0, with J = 0 as the lowest in energy.…”

Excimer Laser Photofragmentation/Fragment Detection for Analysis of the Oxygenated Hydrocarbon Ethyl-3-Ethyoxypropionate: Implications for Atmospheric Monitoring

“…produce carbon atoms in multiple states ( 1 D, 1 S, 3 P) as well as carbon ions. 31,32 CH or CH 2 produced via the pathways previously described may react with these carbons to produce the C 2 molecules observed. Although corroborative data are not available to confirm the above proposed photofragmentation pathways, both are consistent with the production of the observed emission signals corresponding to C 2 and CH molecules, as well as with the relevant bond and photon energies.…”

Silicon transitions, 3p 2→→3p n f (n=4, 5) and 3p 2→→3p 6p, detected in the multiphoton dissociation of phenylsilane

“…The measured REMPI current as a function of The resonances observed in these spectra are quite sharp atomic-like lines, as is clearly seen from these figures and are not due to the target molecule or to molecular fragments. C 6 H 6 and C6HsCHO ) studies [8] which indicate that atomization is favored over ionization. A number of other silicon lines, not included in these figures, were also observed in the present experiments and were assigned to the 3 f ZD~ 3 p 6 p TP transitions.…”

“…Laser photolysis of molecules is so severe, that complete atomization may occur [6][7][8]. The appearance of fragment transitions provides great chances for the study of radicals and very reactive species.…”