A theoretical study on the photodissociation mechanism of acetyl fluoride (CH 3 C(O)F) involving S 0 , S 1 , and T 1 states

Song, Xinli

doi:10.1016/j.chemphys.2017.05.003

Cited by 2 publications

(1 citation statement)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Acetyl halides (CH 3 C(O)X, henceforth AcX), which contain both CO and C–X chromophores, serve as a unique class of molecules in which competing photodissociation pathways arise due to the involvement of both nπ CO * and nσ C–X * states. The investigation of acetyl halide photodissociation has been the subject of several publications examining the energy content of the dissociation end-products. − Of the acetyl halides, AcCl is the most extensively studied system. − The UV absorption spectrum of AcCl shows a nπ * absorption band centered at 240 nm; the nσ * band in AcCl is expected to be in the deep-UV region around 170–200 nm and thus is well separated in energy from the nπ * state. , Butler and co-workers showed that despite the similar bond energies of the α-C–C and α-C–Cl bonds in acetyl chloride, 248 nm excitation of this molecule to the nπ * state first results in the prompt dissociation of the C–Cl bond over a barrier formed from an avoided crossing with the nσ C–Cl * state, and the α-C–C bond is cleaved only via slower secondary dissociation of the acetyl radical. Thus, unlike the Norrish type I pathway in aliphatic aldehydes and ketones following ISC, the primary dissociation in AcCl is thought to occur on singlet states on ultrafast time scales.…”

Section: Introductionmentioning

confidence: 99%

Excited-State Dynamics during Primary C–I Homolysis in Acetyl Iodide Revealed by Ultrafast Core-Level Spectroscopy

et al. 2023

View full text Add to dashboard Cite

In typical carbonyl-containing molecules, bond dissociation events follow initial excitation to nπ C�O * states. However, in acetyl iodide, the iodine atom gives rise to electronic states with mixed nπ C�O * and nσ C−I * character, leading to complex excited-state dynamics, ultimately resulting in dissociation. Using ultrafast extreme ultraviolet (XUV) transient absorption spectroscopy and quantum chemical calculations, we present an investigation of the primary photodissociation dynamics of acetyl iodide via time-resolved spectroscopy of core-to-valence transitions of the I atom after 266 nm excitation. The probed I 4d-to-valence transitions show features that evolve on sub-100-fs time scales, reporting on excited-state wavepacket evolution during dissociation. These features subsequently evolve to yield spectral signatures corresponding to free iodine atoms in their spin−orbit ground and excited states with a branching ratio of 1.1:1 following dissociation of the C−I bond. Calculations of the valence excitation spectrum via equation-of-motion coupled cluster with single and double substitutions (EOM-CCSD) show that initial excited states are of spin-mixed character. From the initially pumped spinmixed state, we use a combination of time-dependent density functional theory (TDDFT)-driven nonadiabatic ab initio molecular dynamics and EOM-CCSD calculations of the N 4,5 edge to reveal a sharp inflection point in the transient XUV signal that corresponds to rapid C−I homolysis. By examining the molecular orbitals involved in the core-level excitations at and around this inflection point, we are able to piece together a detailed picture of C−I bond photolysis in which d → σ* transitions give way to d → p excitations as the bond dissociates. We also report theoretical predictions of short-lived, weak 4d → 5d transitions in acetyl iodide, validated by weak bleaching in the experimental transient XUV spectra. This joint experimental−theoretical effort has thus unraveled the detailed electronic structure and dynamics of a strongly spin−orbit coupled system.

show abstract

Section: Introductionmentioning

confidence: 99%

Excited-State Dynamics during Primary C–I Homolysis in Acetyl Iodide Revealed by Ultrafast Core-Level Spectroscopy

et al. 2023

View full text Add to dashboard Cite

show abstract

Cocrystals with tunable luminescence colour self-assembled by a predictable method

Liu

Wen

et al. 2018

Acta Crystallogr Sect B

View full text Add to dashboard Cite

Organic light-emitting materials play an essential role in the field of luminescent materials because they are easily prepared and they have controllable luminescent properties. Here it is shown that intermolecular interactions and luminescent properties of cocrystals can be predicted using the molecular surface electrostatic potential of selected -hole/-holeÁ Á Á bonding donor haloperfluorobenzenes and acceptor acenaphthene (AC). Single-crystal X-ray diffraction data reveal that actual bonding patterns in five cocrystals assembled from haloperfluorobenzenes and AC are in accordance with predictable patterns of intermolecular interactions; that is -holeÁ Á Á bond is the major interaction in AC-octafluoronaphthalene, AC-1,4-dibromotetrafluorobenzene and AC-1,3,5-tribromo-2,4,6-trifluorobenzene cocrystals, whereas -holeÁ Á Á bond is the major interaction in AC-1,4-diiodotetrafluorobenzene and AC-1,3,5-trifluoro-2,4,6-triiodobenzene cocrystals. The luminescent properties of the cocrystals are affected by the bonding patterns between AC and haloperfluorobenzenes; the -holeÁ Á Á bond leads to weak phosphorescence, whereas the -holeÁ Á Á bond results in weak delayed fluorescence and relatively strong phosphorescence. research papers Acta Cryst. (2018). B74, 610-617 Lili Li et al. Cocrystals with tunable luminescence colour 611 research papers Acta Cryst. (2018). B74, 610-617 Lili Li et al. Cocrystals with tunable luminescence colour 617

show abstract

A theoretical study on the photodissociation mechanism of acetyl fluoride (CH 3 C(O)F) involving S 0 , S 1 , and T 1 states

Cited by 2 publications

References 37 publications

Excited-State Dynamics during Primary C–I Homolysis in Acetyl Iodide Revealed by Ultrafast Core-Level Spectroscopy

Excited-State Dynamics during Primary C–I Homolysis in Acetyl Iodide Revealed by Ultrafast Core-Level Spectroscopy

Cocrystals with tunable luminescence colour self-assembled by a predictable method

Contact Info

Product

Resources

About