The generalized oscillator strengths of the dipole-forbidden excitations of the ^(1)A_(2) of H_(2)O and D_(2)O were calculated with the time dependent density functional theory,by taking into account the vibronic effe...The generalized oscillator strengths of the dipole-forbidden excitations of the ^(1)A_(2) of H_(2)O and D_(2)O were calculated with the time dependent density functional theory,by taking into account the vibronic effect.It is found that the vibronic effect converts the dipole-forbidden excitation of the ^(1)A_(2) into a dipole-allowed one,which enhances the intensities of the corresponding generalized oscillator strength in the small squared momentum transfer region.The present investigation shows that the vibronic effect of H_(2)O is slightly stronger than that of D_(2)O,which exhibits a clear isotopic effect.展开更多
Three kinds of thermochromic materials(DC8,DC12,DC16)were synthesized by linking the rigid 1,4-bis[2-(4-pyridyl)ethenyl]-benzene(bpeb)with different lengths of alkyl chains.They exhibit remarkable fluorescent color ch...Three kinds of thermochromic materials(DC8,DC12,DC16)were synthesized by linking the rigid 1,4-bis[2-(4-pyridyl)ethenyl]-benzene(bpeb)with different lengths of alkyl chains.They exhibit remarkable fluorescent color changes under the irradiation of 365 nm light with elevating temperature,which is supposed to be caused by the transition between the crystal state and the amorphous state.Interestingly,the DC16 solid also has a photochromic character.It should be noticed that the phase transition temperatures of three materials measured by differential scanning calorimetry are higher than those of the fluorescence color changes during the heating process.Thus,the allochroic effect is attributed to the synergistic effect of both heating and photo-inducement(365 nm).Ethanol can turn the heated powder into the initial crystal again which indicates that their thermochromic behavior is reversible and makes the fluorescence recover.展开更多
The electron–ion recombination for phosphorus-like^(112) Sn^(35+)has been measured at the main cooler storage ring of the Heavy Ion Research Facility in Lanzhou, China, employing an electron–ion merged-beams te...The electron–ion recombination for phosphorus-like^(112) Sn^(35+)has been measured at the main cooler storage ring of the Heavy Ion Research Facility in Lanzhou, China, employing an electron–ion merged-beams technique. The absolute total recombination rate coefficients for electron–ion collision energies from 0 e V–14 e V are presented. Theoretical calculations of recombination rate coefficients were performed using the Flexible Atomic Code to compare with the experimental results. The contributions of dielectronic recombination and trielectronic recombination on the experimental rate coefficients have been identified with the help of the theoretical calculation. The present results show that the trielectronic recombination has a substantial contribution to the measured electron–ion recombination spectrum of^(112)Sn^(35+). Although a reasonable agreement is found between the experimental and theoretical results the precise calculation of the electron–ion recombination rate coefficients for M-shell ions is still challengeable for the current theory.展开更多
The sea level in coastal areas of China reached the second highest in 2021,just after that recorded in 2022.External force and dynamic analyses based on tide gauges,satellite observations,reanalysis data and regional ...The sea level in coastal areas of China reached the second highest in 2021,just after that recorded in 2022.External force and dynamic analyses based on tide gauges,satellite observations,reanalysis data and regional numerical outputs were conducted to understand these abnormally high sea levels and determine their possible causes.Results show that the coastal sea level of China had increased at an annual rate of 3.4±0.3 mm during 1980-2021,with an acceleration of 0.06±0.02 mm per year2.The superposition of significant oscillations of quasi-2,3-7,quasi-9,quasi-11,quasi-19 and 20-30 years contributed to the anomalously high sea levels.The negative-phased El Nino/Southern Oscillation was correlated with the anomalously high sea level and the north-south anti-phase pattern of the coastal sea level in 2021.Meanwhile,phase lags of 1-4 months occurred with the sea-level response.On a decadal timescale,the Pacific Decadal Oscillation(PDO)was negatively correlated with the anomalous mean sea level(MSL),and the negative-phased PDO contributed to the anomalous sea-level change in 2021.Particularly,the monthly MSL peaked in April and July,and the contribution of wind stress to the anomalously high sea level was 38.5%in the south of the Taiwan Strait in April and 30%along the coast of China in July.These results were consistent with the tide gauge and satellite data.Close agreement was also observed between the coastal sea-level fingerprint and the air and sea surface temperatures.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12334010,12174259,and 11604003)。
文摘The generalized oscillator strengths of the dipole-forbidden excitations of the ^(1)A_(2) of H_(2)O and D_(2)O were calculated with the time dependent density functional theory,by taking into account the vibronic effect.It is found that the vibronic effect converts the dipole-forbidden excitation of the ^(1)A_(2) into a dipole-allowed one,which enhances the intensities of the corresponding generalized oscillator strength in the small squared momentum transfer region.The present investigation shows that the vibronic effect of H_(2)O is slightly stronger than that of D_(2)O,which exhibits a clear isotopic effect.
基金supported by the National Natural Science Foundation of China(No.21573092,No.21573087 and No.21873039)。
文摘Three kinds of thermochromic materials(DC8,DC12,DC16)were synthesized by linking the rigid 1,4-bis[2-(4-pyridyl)ethenyl]-benzene(bpeb)with different lengths of alkyl chains.They exhibit remarkable fluorescent color changes under the irradiation of 365 nm light with elevating temperature,which is supposed to be caused by the transition between the crystal state and the amorphous state.Interestingly,the DC16 solid also has a photochromic character.It should be noticed that the phase transition temperatures of three materials measured by differential scanning calorimetry are higher than those of the fluorescence color changes during the heating process.Thus,the allochroic effect is attributed to the synergistic effect of both heating and photo-inducement(365 nm).Ethanol can turn the heated powder into the initial crystal again which indicates that their thermochromic behavior is reversible and makes the fluorescence recover.
基金supported by the National Key Research and Development Program of China(Grant No.2017YFA0402300)the Chinese Academy of Sciencesthe National Natural Science Foundation of China(Grant Nos.U1732133,11320101003,11611530684,and 11604003)
文摘The electron–ion recombination for phosphorus-like^(112) Sn^(35+)has been measured at the main cooler storage ring of the Heavy Ion Research Facility in Lanzhou, China, employing an electron–ion merged-beams technique. The absolute total recombination rate coefficients for electron–ion collision energies from 0 e V–14 e V are presented. Theoretical calculations of recombination rate coefficients were performed using the Flexible Atomic Code to compare with the experimental results. The contributions of dielectronic recombination and trielectronic recombination on the experimental rate coefficients have been identified with the help of the theoretical calculation. The present results show that the trielectronic recombination has a substantial contribution to the measured electron–ion recombination spectrum of^(112)Sn^(35+). Although a reasonable agreement is found between the experimental and theoretical results the precise calculation of the electron–ion recombination rate coefficients for M-shell ions is still challengeable for the current theory.
文摘The sea level in coastal areas of China reached the second highest in 2021,just after that recorded in 2022.External force and dynamic analyses based on tide gauges,satellite observations,reanalysis data and regional numerical outputs were conducted to understand these abnormally high sea levels and determine their possible causes.Results show that the coastal sea level of China had increased at an annual rate of 3.4±0.3 mm during 1980-2021,with an acceleration of 0.06±0.02 mm per year2.The superposition of significant oscillations of quasi-2,3-7,quasi-9,quasi-11,quasi-19 and 20-30 years contributed to the anomalously high sea levels.The negative-phased El Nino/Southern Oscillation was correlated with the anomalously high sea level and the north-south anti-phase pattern of the coastal sea level in 2021.Meanwhile,phase lags of 1-4 months occurred with the sea-level response.On a decadal timescale,the Pacific Decadal Oscillation(PDO)was negatively correlated with the anomalous mean sea level(MSL),and the negative-phased PDO contributed to the anomalous sea-level change in 2021.Particularly,the monthly MSL peaked in April and July,and the contribution of wind stress to the anomalously high sea level was 38.5%in the south of the Taiwan Strait in April and 30%along the coast of China in July.These results were consistent with the tide gauge and satellite data.Close agreement was also observed between the coastal sea-level fingerprint and the air and sea surface temperatures.