The photodissociation dynamics of m-brornofluorobenzene has been experimentally investi- gated at around 240 nrn using the DC-slice velocity map imaging technique. The kinetic energy release spectra and the recoiling ...The photodissociation dynamics of m-brornofluorobenzene has been experimentally investi- gated at around 240 nrn using the DC-slice velocity map imaging technique. The kinetic energy release spectra and the recoiling angular distributions of fragmented Br（2P3/2） and Br（2P1/2） atoms from photodissociation of m-bromofluorobenzene have been measured at diff）rent photolysis wavelengths around 240 nm. The experimental results indicate that two dissociation pathways via （pre-）dissociation of the two low-lying 1ππ excited states dominate the production process of the ground state Br（2P3/2） atoms. Because of the weak spin-orbit coupling eff）ct among the low-lying triplet and singlet states, the spin-orbit excited Br（2P1/2） atoms are mainly produced via singlet-triplet state coupling in the dissociation step. The similarity between the present results and that recently reported for o-bromofluorobenzene indicates that the substitution position of the fluorine atom does not significantly affect the UV photodissociation dynamics of bromofluorobenzenes.展开更多
The impact of vertical resolution on the simulation of Typhoon Lekima(2019)is investigated using the Weather Research and Forecasting(WRF)model version 3.8.1.Results show that decreasing vertical grid spacing from app...The impact of vertical resolution on the simulation of Typhoon Lekima(2019)is investigated using the Weather Research and Forecasting(WRF)model version 3.8.1.Results show that decreasing vertical grid spacing from approximately 1000 m to 100 m above 1 km height barely influences the simulated track.However,significant differences are found in the simulated tropical cyclone(TC)structure.The simulation with the coarsest vertical resolution shows a clear double warm-core structure.The upper warm core weakens and even disappears with the increase of vertical resolution.A broader eye and a more slantwise eyewall are observed with the increase of vertical resolution due to the vertically extended lower-level and upper-level outflow,which likely results in a weaker subsidence.Vertical grid convergence is evaluated with the simulated kinetic energy(KE)spectra.As the vertical grid spacing becomes finer than 200 m,convergent KE spectra are found in both the free atmosphere and the outer core of the TC.However,sensitivity tests reveal that the grid convergence is sensitive to the choice of the planetary boundary layer scheme.展开更多
基金financially supported by the National Key R&D Program of China(2017YFA0303502)the National Natural Science Foundation of China(No.21773221 and No.21727804)the Fundamental Research Funds for the Central Universities of China
文摘The photodissociation dynamics of m-brornofluorobenzene has been experimentally investi- gated at around 240 nrn using the DC-slice velocity map imaging technique. The kinetic energy release spectra and the recoiling angular distributions of fragmented Br（2P3/2） and Br（2P1/2） atoms from photodissociation of m-bromofluorobenzene have been measured at diff）rent photolysis wavelengths around 240 nm. The experimental results indicate that two dissociation pathways via （pre-）dissociation of the two low-lying 1ππ excited states dominate the production process of the ground state Br（2P3/2） atoms. Because of the weak spin-orbit coupling eff）ct among the low-lying triplet and singlet states, the spin-orbit excited Br（2P1/2） atoms are mainly produced via singlet-triplet state coupling in the dissociation step. The similarity between the present results and that recently reported for o-bromofluorobenzene indicates that the substitution position of the fluorine atom does not significantly affect the UV photodissociation dynamics of bromofluorobenzenes.
基金sponsored by the Research Program from Science and Technology Committee of Shanghai(No.19dz1200101)the National Key Research and Development Program of China(No.2016YFE0109700)the National Natural Science Foundation of China(Grant No.42075012).
文摘The impact of vertical resolution on the simulation of Typhoon Lekima(2019)is investigated using the Weather Research and Forecasting(WRF)model version 3.8.1.Results show that decreasing vertical grid spacing from approximately 1000 m to 100 m above 1 km height barely influences the simulated track.However,significant differences are found in the simulated tropical cyclone(TC)structure.The simulation with the coarsest vertical resolution shows a clear double warm-core structure.The upper warm core weakens and even disappears with the increase of vertical resolution.A broader eye and a more slantwise eyewall are observed with the increase of vertical resolution due to the vertically extended lower-level and upper-level outflow,which likely results in a weaker subsidence.Vertical grid convergence is evaluated with the simulated kinetic energy(KE)spectra.As the vertical grid spacing becomes finer than 200 m,convergent KE spectra are found in both the free atmosphere and the outer core of the TC.However,sensitivity tests reveal that the grid convergence is sensitive to the choice of the planetary boundary layer scheme.
