Near-UV photodissociation dynamics of formic acid

Langford, Stephen R.; Batten, Alexander D.; Kono, Mitsuhiko; Ashfold, Michael N. R.

doi:10.1039/a704119e

Cited by 35 publications

(55 citation statements)

References 31 publications

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“…In the case of HCOOH, the reaction in Eqn (1) occurs sixfold more frequently than that in Eqn (2). 15,16 In our earlier study of the UV-induced alkylation of inorganic selenium, we speculated that the reaction in Eqn (2) becomes less favorable with increasing carbon chain length because for n = 1 or 2 (acetic or propionic acid) the formation of selenium carbonyl was undetectable. This no longer appears to be the case for nickel.…”

Section: Proposed Mechanismmentioning

confidence: 97%

UV photosynthesis of nickel carbonyl

Guo

Sturgeon

Mester

et al. 2004

Applied Organom Chemis

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In the presence of low-molecular-weight organic acids, such as formic, acetic, and propionic, inorganic nickel salts in aqueous solutions are converted to the volatile tetracarbonyl by UV irradiation. Experiments were performed using a flow-through photoreactor, consisting of a 6 m length polytetrafluoroethylene tubing wrapped around a low-pressure mercury vapor UV lamp (254 nm, 15 W). The efficiency of transformation was estimated to be 95%. As no carbon monoxide or external reductant is required, photochemical synthesis may prove to be useful in material chemistry and applicable to the extractive metallurgy of nickel, as well as its refining and recycling.

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Section: Proposed Mechanismmentioning

confidence: 97%

UV photosynthesis of nickel carbonyl

Guo

Sturgeon

Mester

et al. 2004

Applied Organom Chemis

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“…This is consistent with the H (Rydberg) atom photofragment translational spectroscopy study, which showed that the DC3 occurs exclusively on the T 1 PES after ISC. 35 In this experiment, it was also found that the channel HCOO + H (DC5) takes place on the S 1 PES, and the required energy in this channel (compared with the initial state) was estimated to be ∼532 kJ/mol. As shown in Figure 2, DC5 opens through S 1 -TS3 on the S 1 PES.…”

mentioning

confidence: 98%

“…We will discuss this channel in more detail in connection to a pathway via triplet in a subsequent paragraph. Above 532 kJ/ mol (an experimental threshold), 35 Dissociation Channels below 252 nm; Dissociation via the T 1 PES. Now we look for a channel or channels for dissociation below the S 1 -TS2 threshold.…”

mentioning

confidence: 99%

Automated Exploration of Photolytic Channels of HCOOH: Conformational Memory via Excited-State Roaming

Maeda

Taketsugu

Morokuma

2012

J. Phys. Chem. Lett.

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To elucidate the photodissociation mechanism of HCOOH, we systematically explored reaction pathways starting from the first excited singlet state (S1) by using automated reaction path search methods. All critical points, that is, minima, transition states, minimum energy conical intersections, and minima on seam of crossing, for the S0, T1, and S1 potential energy surfaces (PESs) obtained in the present search were optimized at the CASPT2 level. The structure list obtained by the search explained all experimentally reported photolytic channels. A new mechanism for the previously suggested but unexplained conformational memory in the 193 nm photolysis is proposed, which involves two steps: partial dissociation and succeeding roaming of one of H atoms on the S1 PES, followed by intramolecular recombination on the S0 PES after radiationless transition through a conical intersection at a partially dissociated geometry. This is partially similar to the excited-state roaming recently discovered for the NO3 radical.

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“…[5][6][7][8][9][10][11] The major primary dissociation channel has been found to produce the CHO and OH radicals with quantum yield of 0.70 at 222 nm. 12 It was suggested that the dissociation should be predissociative and the potential energy surface leading to the CHO and OH radical products has an exit channel barrier.…”

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confidence: 99%