We revisit the laser-intensity-dependent ionization and fragmentation yields of C60 molecules irradiated by 25-fs,798-nm laser pulses based on the approach in which photoions are measured via a velocity map imaging sp...We revisit the laser-intensity-dependent ionization and fragmentation yields of C60 molecules irradiated by 25-fs,798-nm laser pulses based on the approach in which photoions are measured via a velocity map imaging spectrometer working in a time-sliced mode.This approach dramatically improves the signal-to-background ratio compared to those using a simple(traditional)time-of-flight mode(spectrometer),and thus allows us to measure the laser-intensity dependences down to a previously untouched region,which is expected to provide new insights into the intense-field ionization and fragmentation of C60.Indeed,we find that the saturation intensities for C60 ionizations and the onset intensity for C60 fragmentation are much lower than those reported in previous experiments.Furthermore,the derived saturation-intensity dependence on charge distribution demonstrates the validity of the over-the-barrier ionization using a conducting sphere model.展开更多
The direct Coulomb explosion of N2O2+has been investigated experimentally after double-ionization by a single extreme ultraviolet(EUV)photon with an energy of ~38.5 eV.From the ion–ion time-of-flight coincidence spec...The direct Coulomb explosion of N2O2+has been investigated experimentally after double-ionization by a single extreme ultraviolet(EUV)photon with an energy of ~38.5 eV.From the ion–ion time-of-flight coincidence spectrum,the de-nitrogenation(N2O2+→N++NO+)and de-oxygenation(N2O2+→O++N+2)photodissociation channels of N2O2+are unequivocally identified.The measured kinetic energy release(KER)distribution of the de-nitrogenation channel presents a major peak accompanied by a shoulder structure.We find that the major peak can be attributed to the direct photodissociation of the 11△and 1^1Σ+states,while the shoulder structure should be ascribed to the predissociation of the1^1△and 1^1Σ+states via 13Πstate.展开更多
基金the National Key R&D Program(Grant No.2017YFA0402300)the National Natural Science Foundation of China(Grant Nos.11974359 and U1632143)。
文摘We revisit the laser-intensity-dependent ionization and fragmentation yields of C60 molecules irradiated by 25-fs,798-nm laser pulses based on the approach in which photoions are measured via a velocity map imaging spectrometer working in a time-sliced mode.This approach dramatically improves the signal-to-background ratio compared to those using a simple(traditional)time-of-flight mode(spectrometer),and thus allows us to measure the laser-intensity dependences down to a previously untouched region,which is expected to provide new insights into the intense-field ionization and fragmentation of C60.Indeed,we find that the saturation intensities for C60 ionizations and the onset intensity for C60 fragmentation are much lower than those reported in previous experiments.Furthermore,the derived saturation-intensity dependence on charge distribution demonstrates the validity of the over-the-barrier ionization using a conducting sphere model.
基金National Key Research and Development Program of China(Grant No.2017YFA0402300).
文摘The direct Coulomb explosion of N2O2+has been investigated experimentally after double-ionization by a single extreme ultraviolet(EUV)photon with an energy of ~38.5 eV.From the ion–ion time-of-flight coincidence spectrum,the de-nitrogenation(N2O2+→N++NO+)and de-oxygenation(N2O2+→O++N+2)photodissociation channels of N2O2+are unequivocally identified.The measured kinetic energy release(KER)distribution of the de-nitrogenation channel presents a major peak accompanied by a shoulder structure.We find that the major peak can be attributed to the direct photodissociation of the 11△and 1^1Σ+states,while the shoulder structure should be ascribed to the predissociation of the1^1△and 1^1Σ+states via 13Πstate.
