Study On H₂CC^-/FCH₃OH^- By Photodetachment Dynamics And On H₂+H₂CO By Collision Dynamics

Molecular reaction dynamics is a science that explores the microscopic mechanism of chemical reactions at the atomic/molecular level.The molecular reaction dynamics comply with the basic principles of quantum mechanics.Thus,one can separate the motion of electrons and nuclei for multi-electrons system based on the Born Oppenheimer(B-O)approximation,which greatly simplifies the solving of Schrodinger equation.The high-precision potential energy surface(PES)can be constructed based on the potential energies of different configurations using quantum chemistry method,then all the dynamics informations can be obtained via solving the Schrodinger equation.The commonly theorical methods used in molecular reaction dynamics are quantum mechanical(QM)method and quasi-classical trajectory(QCT)method.Detailed investigation on molecular reaction dynamics is important for us to better understand,utilize and control the chemical reactions.Therefore,in this paper,the photodetachment dynamics of H2CC/FCH3OH anion and the inelastic collision dynamics of H2+H2CO are studied.The main contents and innovations are as follows:(1)Photodetachment dynamics study on H2CC-using QM method.Vinylidene(H2CC)is a high-energy-isomer of acetylene(HCCH).The small isomerization barrier between HCCH and H2CC(～0.1 eV)determines the high isomerization possibility between them.They are also a typical example of 1,2-hydrogen transfer.Besides,HCCH and H2CC are important intermediates in the combustion reaction.Therefore,a further study on this isomerization process can help us to have a deep understanding of combustion reaction.Thus,we explore the isomerization process between HCCH and H2CC via photodetachment electron spectroscopy method in this work.First,an accurate full-dimensional PES for H2CC anions was constructed and optimized using Permutation Invariant Polynomialneural Neural Network(PIPNN)method in cooperiation with Han et al.Based on this PES,the fine photoelectron spectra of H2CC anions were calculated QM method.Besides,a triple well was found on the PES for the first time.Then,the high-resolution photoelectron spectra of H2CC anion were measured by our co-worker.At the same time,more detailed quantum dynamics calculations were conducted.Fermi resonances were found via this detailed experimental and theoretical study,which induce the occurrence of two obvious difference areas between the experimental and theorical photoelectron spectra.Moreover,abnormal phenomenon that isomerization was more likely to take place for the state with low energy was found in this study.Next,the existence of vinyliene triple well was verified with the help of high-resolution Cryo-SEVI experiments.Last but not the least,Cryo-SEVI experiments was employed to study the highly excited vibrational states of neutral H2CC.The results identified the singlet excited state A1A2(S1)of neutral H2CC for the first time.These results greatly promote our understanding of the isomerization process from a new perspective,and provide important lessons for the future investigation.(2)Photodetachment dynamics study on FCH3OH-via QM method.F+CH3OH→FH+CH3O is a typical hydrogen extraction reaction.And the resultant radical CH3O is an important intermediate of hydrocarbon fuel combustion,atmospheric chemistry,surface science,interstellar chemistry,and so on.Also,this reaction is an important path to produce CH3O radical or vibrational excited HF molecule.Therefore,the reaction process of F+CH3OH→FH+CH3O reaction was investigated via Photodetachment electron spectroscopy method.First,an accurate PES for FCH3OH anion were constructed and optimized via PIP-NN method with the help of prof.Li Jun.Then,the photoelectron spectra of FCH3OH anion was calculated based on this PES.There was an interesting phenomenon that the spacing corresponding to the fine peaks in photoelectron spectroscopy becomes wider with the increase of the vibrational quantum number of HF.This was proved to be caused by the other more fine peaks included in the fine peaks.Also,a Feshbach resonance was confirmed in the product channel of this reaction.In addition,the Photoelectron-Photofragment Coincidence(PPC)spectrum of FCH3OH anion was simulated in this work.The experimental spectrum was reasonably reproduced by our calculation.Furthermore,this work revels that there is vibrational excitation in HF with VHF=1,2 as the largest population,while CH3O serves largely as a spectator.These results are beneficial for us to obtain a more complete dynamic picture of this reaction,especially in the region of the post transition state on the neutral PES.(3)Inelastic collision dynamics study on H2+H2CO using QCT method.Inelastic collisions account for a large proportion in the combustion process.The study of inelastic collision between molecules therefore is needed for us to understand the combustion reactions.H2 and H2CO are the important intermediate products of combustion reactions,thus the study on the inelastic collision dynamics between H2 and H2CO is important for us to have a better understanding of the combustion process.The inelastic collisions between H2 and H2CO were explored using QCT method in this work.First,an accurate and efficiency full-dimensional PES was constructed using PIP-NN method.Then,the inelastic collision dynamics process was simulated based on this PES using QCT method.The results show that with the increase of collision energy EC and the vibrational quantum number of H2CO.The total energy transfer distribution and vibrational energy transfer distribution of H2 and H2CO deviate from the exponential distribution.It means that the collision between molecules is more sufficient.These studies lay a well foundation for our better understanding of the molecular collision and combustion reaction.