A graphically oriented interactive program for assignments of rotationally resolved molecular spectra has been devised. The program functions by grouping spectral lines in term of the second difference principle. and ...A graphically oriented interactive program for assignments of rotationally resolved molecular spectra has been devised. The program functions by grouping spectral lines in term of the second difference principle. and graphing spectral intensity versus frequency in a bar graph of the selected groups, distinguished by color and/or line-type. This allows for easy detection of regular patterns buried in the observed spectrum. Furthermore, it includes a Loomis-Wood view for assisting in spectral assignments. As an example, the program was applied in assigning the molecular spectrum of the production in the discharge of PCl3 buffered by helium gas, which may belong to several species. The results suggest that the program is highly efficient and quite useful in the assignment and the analysis of molecular spectra, especially those of symmetric top, slightly asymmetric top and linear molecules. The accuracy and efficiency of this program will likely ensure its wide application in the processing of molecular spectra.展开更多
Time-resolved fluorescence spectra of europium methylbenzoates (MBA)with 1,10-phenanthroline(phen)have been measured at room temperature.For each of the europium chelates,where the ligand triple states lie above the ~...Time-resolved fluorescence spectra of europium methylbenzoates (MBA)with 1,10-phenanthroline(phen)have been measured at room temperature.For each of the europium chelates,where the ligand triple states lie above the ~5D_1 level of Eu^(3-),the spectra providc evidence that the Eu^(3-) ~5D_0 state is populated by nonradiative energy transfer from the higher-lying ~5D_1,state.The relaxation time for energy decay from ~5D_1 state is measured in the microcrystals to bc of the order of a few microseconds.It is suggested that the ligand C=0 and C=C stretching vibrations and Eu-O vibrations,chclate ring and benzene ring vibrations make important contributions to the relaxation process.The ~5D\-1—~5D\-0 relaxation time of Eu- (p-MBA)_3phen is shorter than those of Eu(m-MBA)_3phen and Eu(o-MBA)_3phen since nonradiative degradation to ~5D_0 from ~5D_1 appears to be more strongly influenced by the E_u^(3+)sites in the former.展开更多
he photoluminescence spectra of porous Si have been studied. Its timere-solved luminescence spectra show a red shift of luminescencc peak with increasingdelay time after exciting and a nonexponential decay. Several sp...he photoluminescence spectra of porous Si have been studied. Its timere-solved luminescence spectra show a red shift of luminescencc peak with increasingdelay time after exciting and a nonexponential decay. Several spectral bands withdifferent Gaussian center appear by means of the decomposition of a spetrum. Theresuits of our experiments show quantum confined characters in porous Si, and wespeculate that the short wavelength band at 465 nm is the direct band froni P_(15) toP_(25)展开更多
A nested genetic algorithm, including genetic parameter level and genetic implemented level for peak parameters, was proposed and applied for resolving overlapped spectral bands. By the genetic parameter level, parame...A nested genetic algorithm, including genetic parameter level and genetic implemented level for peak parameters, was proposed and applied for resolving overlapped spectral bands. By the genetic parameter level, parameters of generic algorithm were optimized; moreover, the number of overlapped peaks was determined simultaneously Then parameters of individual peaks were computed with the genetic implemented level.展开更多
Angle-resolved photoemission spectra(ARPES) are calculated in the Hubbard model by using cluster perturbation method. It is found that in a cluster of 12 sites, the local density of states displays the phase transitio...Angle-resolved photoemission spectra(ARPES) are calculated in the Hubbard model by using cluster perturbation method. It is found that in a cluster of 12 sites, the local density of states displays the phase transition from normal conductor to Mott insulator with the increase of the electron-electron coupling. We show that a pseudogap develops from the metallic phase to the insulating phase. Evidence of spin-charge separation is also verified in the calculated single particle spectral functions.展开更多
Magnesium monofluoride(MgF)is proposed as an ideal candidate radical for direct laser cooling.Here,the rotationally resolved laser spectra of MgF for the A^(2)Π-X^(2)∑^(+) electronic transition system were recorded ...Magnesium monofluoride(MgF)is proposed as an ideal candidate radical for direct laser cooling.Here,the rotationally resolved laser spectra of MgF for the A^(2)Π-X^(2)∑^(+) electronic transition system were recorded by using laser induced fluorescence technique.The MgF radicals were produced by discharging SF_(6)/Ar gas mixtures between the tips of two magnesium needles in a supersonic jet expansion.We recorded a total of 19 vibrational bands belonging to three sequences of Δv=0,±1 in the region of 348-370 nm.Accurate spectroscopic constants for both X^(2)∑^(+) and A^(2)Π states are determined from rotational analysis of the experimental spectra.Spectroscopic parameters,including the Franck-Condon factors(FCFs),are determined from the experimental results and the Rydberg-Klein-Rees(RKR)calculations.Significant discrepancies between the experimentally measured and RKR-calculated FCFs are found,indicating that the FCFs are nearly independent of the spin-orbit coupling in the A^(2)Π state.Potential energy curves(PECs)and FCFs determined here provide necessary data for the theoretical simulation of the laser-cooling scheme of MgF.展开更多
IN a previous paper, we have studied the energy transfer mechanism among the PBS-thy-lakoid complex in detail by using steady-state spectra and deconvolution techniques. The ex-perimental results indicated that the en...IN a previous paper, we have studied the energy transfer mechanism among the PBS-thy-lakoid complex in detail by using steady-state spectra and deconvolution techniques. The ex-perimental results indicated that the energy transfer from PBS to two reaction centers of PS Ⅰand PS Ⅱ were parallel, and confirmed the model which was suggested by Mullineaxu.展开更多
The title compound 1,3,3,5,2'-pentamethylspirooxazine (I) is synthesized and identified by 1R, 1H NMR and elemental analysis. The time-resolved transient absorption spectra of I are investigated by nanosecond lase...The title compound 1,3,3,5,2'-pentamethylspirooxazine (I) is synthesized and identified by 1R, 1H NMR and elemental analysis. The time-resolved transient absorption spectra of I are investigated by nanosecond laser flash photolysis. The photolysis of I in solution excited by 248 nm laser pulse results in two different colored species. One of them is a short-lived species (CT intermediate), which has two absorption maxima at 440 and 640 nm in acetonitrile, and 450 and 640 nm in cyclohexane. The corresponding lifetimes are 12 and 0.8 us, respectively. The absorption spectra of CT intermediate are not influenced by solvent polarity. This fact indicates that the structure of CT is between the zwitterionic and quinoidal ones. The much longer lifetime of CT in acetonitrile than in cyclohexane is due to the electron donating effect of methyl in position 5 of indolino ring. The long-lived colored species (>>80 us) proves a planar photomerocyanine (PMC) structure, whose absorption spectra in acetonitrile and cyclohexane show the absorption maxima at 640 and 600nm, respectively.展开更多
对基于空间可分辨光谱的番茄成熟度分类判别方法进行了试验研究。首先根据番茄的内部颜色,将600个番茄分为6个不同成熟度(green,breaker,turning,pink,light red and red),然后用自行开发的多通道高光谱成像探头采集番茄的空间可分辨(SR...对基于空间可分辨光谱的番茄成熟度分类判别方法进行了试验研究。首先根据番茄的内部颜色,将600个番茄分为6个不同成熟度(green,breaker,turning,pink,light red and red),然后用自行开发的多通道高光谱成像探头采集番茄的空间可分辨(SR)光谱,建立基于空间可分辨光谱的番茄成熟度偏最小二乘判别(PLSDA)模型和支持向量机判别(SVMDA)模型。结果显示,对于PLSDA模型,SR光谱15为最佳分类光谱,分类正确率达到81.3%;对于SVMDA模型,SR光谱10为最佳预测分类光谱,分类正确率为86.3%。对六个成熟度等级番茄的判别分类,SVMDA模型要明显优于PLSDA模型。此外,相对于较小的光源-检测器距离SR光谱,较大的光源-检测器距离SR光谱可以获得更好的判别效果,显示出空间可分辨光谱在果蔬品质检测方面的应用潜力。展开更多
基金This work was supported by the National Natural Science Foundation of China （NSFC No.10574045 and No.10434060）and Science and Technology Commission of Shanghai Municipality（No.04DZ14009）.The authors are grateful to Hua-huiZhu for his valuable suggestions.
文摘A graphically oriented interactive program for assignments of rotationally resolved molecular spectra has been devised. The program functions by grouping spectral lines in term of the second difference principle. and graphing spectral intensity versus frequency in a bar graph of the selected groups, distinguished by color and/or line-type. This allows for easy detection of regular patterns buried in the observed spectrum. Furthermore, it includes a Loomis-Wood view for assisting in spectral assignments. As an example, the program was applied in assigning the molecular spectrum of the production in the discharge of PCl3 buffered by helium gas, which may belong to several species. The results suggest that the program is highly efficient and quite useful in the assignment and the analysis of molecular spectra, especially those of symmetric top, slightly asymmetric top and linear molecules. The accuracy and efficiency of this program will likely ensure its wide application in the processing of molecular spectra.
文摘Time-resolved fluorescence spectra of europium methylbenzoates (MBA)with 1,10-phenanthroline(phen)have been measured at room temperature.For each of the europium chelates,where the ligand triple states lie above the ~5D_1 level of Eu^(3-),the spectra providc evidence that the Eu^(3-) ~5D_0 state is populated by nonradiative energy transfer from the higher-lying ~5D_1,state.The relaxation time for energy decay from ~5D_1 state is measured in the microcrystals to bc of the order of a few microseconds.It is suggested that the ligand C=0 and C=C stretching vibrations and Eu-O vibrations,chclate ring and benzene ring vibrations make important contributions to the relaxation process.The ~5D\-1—~5D\-0 relaxation time of Eu- (p-MBA)_3phen is shorter than those of Eu(m-MBA)_3phen and Eu(o-MBA)_3phen since nonradiative degradation to ~5D_0 from ~5D_1 appears to be more strongly influenced by the E_u^(3+)sites in the former.
文摘he photoluminescence spectra of porous Si have been studied. Its timere-solved luminescence spectra show a red shift of luminescencc peak with increasingdelay time after exciting and a nonexponential decay. Several spectral bands withdifferent Gaussian center appear by means of the decomposition of a spetrum. Theresuits of our experiments show quantum confined characters in porous Si, and wespeculate that the short wavelength band at 465 nm is the direct band froni P_(15) toP_(25)
文摘A nested genetic algorithm, including genetic parameter level and genetic implemented level for peak parameters, was proposed and applied for resolving overlapped spectral bands. By the genetic parameter level, parameters of generic algorithm were optimized; moreover, the number of overlapped peaks was determined simultaneously Then parameters of individual peaks were computed with the genetic implemented level.
基金Supported by the National Natural Science Foundation of China(No11075196)
文摘Angle-resolved photoemission spectra(ARPES) are calculated in the Hubbard model by using cluster perturbation method. It is found that in a cluster of 12 sites, the local density of states displays the phase transition from normal conductor to Mott insulator with the increase of the electron-electron coupling. We show that a pseudogap develops from the metallic phase to the insulating phase. Evidence of spin-charge separation is also verified in the calculated single particle spectral functions.
基金supports from the National Natural Science Foundation of China(No.21773221 and No.21827804)the National Key R&D Program of China(No.2017YFA0303502)the Fundamental Research Funds for the Central Universities of China(No.WK2340000078)。
文摘Magnesium monofluoride(MgF)is proposed as an ideal candidate radical for direct laser cooling.Here,the rotationally resolved laser spectra of MgF for the A^(2)Π-X^(2)∑^(+) electronic transition system were recorded by using laser induced fluorescence technique.The MgF radicals were produced by discharging SF_(6)/Ar gas mixtures between the tips of two magnesium needles in a supersonic jet expansion.We recorded a total of 19 vibrational bands belonging to three sequences of Δv=0,±1 in the region of 348-370 nm.Accurate spectroscopic constants for both X^(2)∑^(+) and A^(2)Π states are determined from rotational analysis of the experimental spectra.Spectroscopic parameters,including the Franck-Condon factors(FCFs),are determined from the experimental results and the Rydberg-Klein-Rees(RKR)calculations.Significant discrepancies between the experimentally measured and RKR-calculated FCFs are found,indicating that the FCFs are nearly independent of the spin-orbit coupling in the A^(2)Π state.Potential energy curves(PECs)and FCFs determined here provide necessary data for the theoretical simulation of the laser-cooling scheme of MgF.
文摘IN a previous paper, we have studied the energy transfer mechanism among the PBS-thy-lakoid complex in detail by using steady-state spectra and deconvolution techniques. The ex-perimental results indicated that the energy transfer from PBS to two reaction centers of PS Ⅰand PS Ⅱ were parallel, and confirmed the model which was suggested by Mullineaxu.
基金Project supported by the National Natural Science Foundation of China and Chinese Academy of Sciences.
文摘The title compound 1,3,3,5,2'-pentamethylspirooxazine (I) is synthesized and identified by 1R, 1H NMR and elemental analysis. The time-resolved transient absorption spectra of I are investigated by nanosecond laser flash photolysis. The photolysis of I in solution excited by 248 nm laser pulse results in two different colored species. One of them is a short-lived species (CT intermediate), which has two absorption maxima at 440 and 640 nm in acetonitrile, and 450 and 640 nm in cyclohexane. The corresponding lifetimes are 12 and 0.8 us, respectively. The absorption spectra of CT intermediate are not influenced by solvent polarity. This fact indicates that the structure of CT is between the zwitterionic and quinoidal ones. The much longer lifetime of CT in acetonitrile than in cyclohexane is due to the electron donating effect of methyl in position 5 of indolino ring. The long-lived colored species (>>80 us) proves a planar photomerocyanine (PMC) structure, whose absorption spectra in acetonitrile and cyclohexane show the absorption maxima at 640 and 600nm, respectively.
文摘对基于空间可分辨光谱的番茄成熟度分类判别方法进行了试验研究。首先根据番茄的内部颜色,将600个番茄分为6个不同成熟度(green,breaker,turning,pink,light red and red),然后用自行开发的多通道高光谱成像探头采集番茄的空间可分辨(SR)光谱,建立基于空间可分辨光谱的番茄成熟度偏最小二乘判别(PLSDA)模型和支持向量机判别(SVMDA)模型。结果显示,对于PLSDA模型,SR光谱15为最佳分类光谱,分类正确率达到81.3%;对于SVMDA模型,SR光谱10为最佳预测分类光谱,分类正确率为86.3%。对六个成熟度等级番茄的判别分类,SVMDA模型要明显优于PLSDA模型。此外,相对于较小的光源-检测器距离SR光谱,较大的光源-检测器距离SR光谱可以获得更好的判别效果,显示出空间可分辨光谱在果蔬品质检测方面的应用潜力。
