This paper calculates quantum-mechanically the photoelectron energy spectra excited by attosecond x-rays in the presence of a few-cycle laser. A photoelectron laser phase determination method is used for precise measu...This paper calculates quantum-mechanically the photoelectron energy spectra excited by attosecond x-rays in the presence of a few-cycle laser. A photoelectron laser phase determination method is used for precise measurements of the pulse natural properties of x-ray intensity and the instantaneous frequency profiles. As a direct procedure without any previous pulse profile assumptions and time-resolved measurements as well as data fitting analysis, this method can be used to improve the time resolutions of attosecond timing and measurements with metrological precision. The measurement range is half of a laser optical cycle.展开更多
In this paper the laser-phase determination methods and transfer equations are presented to directly reconstruct the detailed temporal structures of ultra-short extreme ultraviolet （xuv） pulses from the measured pho...In this paper the laser-phase determination methods and transfer equations are presented to directly reconstruct the detailed temporal structures of ultra-short extreme ultraviolet （xuv） pulses from the measured photoelectron energy spectra （PES）. Each transfer equation includes one of PID （proportional-integral-differential） terms of PES. The intensity and instantaneous frequency of attosecond xuv can be retrieved from the integral term of PES. The intensity profiles of narrow bandwidth atto- and femtosecond xuvs can be rebuilt from the proportional and differential terms of PES respectively. The methods and equations may be used to improve time resolutions in measuring ultrashort pulses.展开更多
The photoelectron energy spectra （PESs） excited by narrow bandwidth attosecond x-ray pulses in the presence of a few-cycle laser are quantum-mechanically calculated. Transfer equations are used to reconstruct the de...The photoelectron energy spectra （PESs） excited by narrow bandwidth attosecond x-ray pulses in the presence of a few-cycle laser are quantum-mechanically calculated. Transfer equations are used to reconstruct the detailed temporal structure of an attosecond x-ray pulse directly from a measured PES. Theoretical analysis shows that the temporal uncertainties of the pulse reconstruction depend on the x-ray bandwidth. The procedure of pulse reconstruction is direct and simple without making any previous pulse assumption, data fitting analysis and time-resolved measurement of PESs. The temporal measurement range is half of a laser optical cycle.展开更多
To study the time evolution of a molecular state in an ultra-fast chemical reaction,the use of shorter pulses with higher photon energy and narrower bandwidth for both pump and probe is necessary.However,quick and pre...To study the time evolution of a molecular state in an ultra-fast chemical reaction,the use of shorter pulses with higher photon energy and narrower bandwidth for both pump and probe is necessary.However,quick and precise measurement of their detailed time structures is a challenge.Over the last decade,great efforts have been made to measure an attosecond extreme ultraviolet (XUV) pulse.To date,several methods have been developed to measure the pulse duration and completely reconstruct it.The attosecond spectral phase interferometry for direct electric field reconstruction (SPIDER) and attosecond frequency-resolved optical gating (FROG) techniques are often used.However,these methods use state-of-the-art experimental set-ups and complicated data analysis procedures.To develop attosecond metrology for practical use (e.g.timing,measurement,evaluation,calibration,optimization,pumping,probing),we propose a quick and analytical method to precisely observe an attosecond XUV pulse with laser-assisted photo-ionization.The method is based on determining the laser-related phase of each streaked electron and using a transfer equation for one-step pulse reconstruction without any time-resolved measurements,iterative calculations,or data fitting procedures.Temporal errors of the pulse reconstruction are calculated from the XUV bandwidth.Because the transfer equation establishes a direct connection between the XUV pulse properties,the crucial laser parameters (peak intensity,phase,carrier envelope phase),the atomic ionization potential,and the measured photoelectron energy spectrum,we can use it to study any one of these properties from other known information and probe the dynamic processes of an ultra-fast reaction.展开更多
We have measured the synchrotron radiation photoelectron spectra of monolayer C60on Ag（100）, By calculating the intensity ratios between the LUMO bands and the two deeper bands （HOMO and HOMO- 1）, we estimate the ...We have measured the synchrotron radiation photoelectron spectra of monolayer C60on Ag（100）, By calculating the intensity ratios between the LUMO bands and the two deeper bands （HOMO and HOMO- 1）, we estimate the amount of the charges transferred from Ag（100） to C60 within the range of 1 e to 1.8 e. The results dismay the expectation of surface superconductivity and afford a good reference for further studies of the monolayer C60/Ag（100） system.展开更多
High-rate CO_(2)-to-CH_(4)photoreduction with high selectivity is highly attractive,which is a win-win strategy for mitigating the greenhouse effect and the energy crisis.However,the poor photocatalytic activity and l...High-rate CO_(2)-to-CH_(4)photoreduction with high selectivity is highly attractive,which is a win-win strategy for mitigating the greenhouse effect and the energy crisis.However,the poor photocatalytic activity and low product selectivity hinder the practical application.To precisely tailor the product selectivity and realize high-rate CO_(2)photoreduction,we design atomically precise Pd species supported on In_(2)O_(3)nanosheets.Taking the synthetic 1.30Pd/In_(2)O_(3)nanosheets as an example,the aberration-correction high-angle annular dark-field scanning transmission electron microscopy image displayed the Pd species atomically dispersed on the In_(2)O_(3)nanosheets.Raman spectra and X-ray photoelectron spectra established that the strong interaction between the Pd species and the In_(2)O_(3)substrate drove electron transfer from In to Pd species,resulting in electron-enriched Pd sites for CO_(2)activation.Synchrotronradiation photoemission spectroscopy demonstrated that the Pd species can tailor the conduction band edge of In_(2)O_(3)nanosheets to match the CO_(2)-to-CH_(4)pathway,instead of the CO_(2)-to-CO pathway,which theoretically accounts for the high CH_(4)selectivity.Moreover,in situ X-ray photoelectron spectroscopy unveiled that the catalytically active sites had a change from In species to Pd species over the 1.30Pd/In_(2)O_(3)nanosheets.In situ FTIR and EPR spectra reveal the atomically precise Pd species with rich electrons prefer to adsorb the electrophilic protons for accelerating the*COOH intermediates hydrogenation into CH_(4).Consequently,the 1.30Pd/In_(2)O_(3)nanosheets reached CO_(2)-to-CH_(4)photoconversion with 100%selectivity and 81.2μmol g^(−1)h^(−1)productivity.展开更多
文摘This paper calculates quantum-mechanically the photoelectron energy spectra excited by attosecond x-rays in the presence of a few-cycle laser. A photoelectron laser phase determination method is used for precise measurements of the pulse natural properties of x-ray intensity and the instantaneous frequency profiles. As a direct procedure without any previous pulse profile assumptions and time-resolved measurements as well as data fitting analysis, this method can be used to improve the time resolutions of attosecond timing and measurements with metrological precision. The measurement range is half of a laser optical cycle.
文摘In this paper the laser-phase determination methods and transfer equations are presented to directly reconstruct the detailed temporal structures of ultra-short extreme ultraviolet （xuv） pulses from the measured photoelectron energy spectra （PES）. Each transfer equation includes one of PID （proportional-integral-differential） terms of PES. The intensity and instantaneous frequency of attosecond xuv can be retrieved from the integral term of PES. The intensity profiles of narrow bandwidth atto- and femtosecond xuvs can be rebuilt from the proportional and differential terms of PES respectively. The methods and equations may be used to improve time resolutions in measuring ultrashort pulses.
基金supported by the National Key Basic Research Program of China(973)(2012CB21500203)Dean Project of Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology,China(2013K009,2013Z001)~~
基金Project supported by the National Natural Science Foundation of China (Grant No 10675014)
文摘The photoelectron energy spectra （PESs） excited by narrow bandwidth attosecond x-ray pulses in the presence of a few-cycle laser are quantum-mechanically calculated. Transfer equations are used to reconstruct the detailed temporal structure of an attosecond x-ray pulse directly from a measured PES. Theoretical analysis shows that the temporal uncertainties of the pulse reconstruction depend on the x-ray bandwidth. The procedure of pulse reconstruction is direct and simple without making any previous pulse assumption, data fitting analysis and time-resolved measurement of PESs. The temporal measurement range is half of a laser optical cycle.
基金supported by the National Natural Science Foundation of China (10827505 and 10675014)
文摘To study the time evolution of a molecular state in an ultra-fast chemical reaction,the use of shorter pulses with higher photon energy and narrower bandwidth for both pump and probe is necessary.However,quick and precise measurement of their detailed time structures is a challenge.Over the last decade,great efforts have been made to measure an attosecond extreme ultraviolet (XUV) pulse.To date,several methods have been developed to measure the pulse duration and completely reconstruct it.The attosecond spectral phase interferometry for direct electric field reconstruction (SPIDER) and attosecond frequency-resolved optical gating (FROG) techniques are often used.However,these methods use state-of-the-art experimental set-ups and complicated data analysis procedures.To develop attosecond metrology for practical use (e.g.timing,measurement,evaluation,calibration,optimization,pumping,probing),we propose a quick and analytical method to precisely observe an attosecond XUV pulse with laser-assisted photo-ionization.The method is based on determining the laser-related phase of each streaked electron and using a transfer equation for one-step pulse reconstruction without any time-resolved measurements,iterative calculations,or data fitting procedures.Temporal errors of the pulse reconstruction are calculated from the XUV bandwidth.Because the transfer equation establishes a direct connection between the XUV pulse properties,the crucial laser parameters (peak intensity,phase,carrier envelope phase),the atomic ionization potential,and the measured photoelectron energy spectrum,we can use it to study any one of these properties from other known information and probe the dynamic processes of an ultra-fast reaction.
基金Supported by National Natural Science Foundation of China (10674115)BSRFRDF of NJUST (AB96331)
文摘We have measured the synchrotron radiation photoelectron spectra of monolayer C60on Ag（100）, By calculating the intensity ratios between the LUMO bands and the two deeper bands （HOMO and HOMO- 1）, we estimate the amount of the charges transferred from Ag（100） to C60 within the range of 1 e to 1.8 e. The results dismay the expectation of surface superconductivity and afford a good reference for further studies of the monolayer C60/Ag（100） system.
基金the National Key R&D Program of China(2022YFA1502904,2019YFA0210004,2021YFA1501502)National Natural Science Foundation of China(22125503,21975242,U2032212,21890754)+1 种基金Youth Innovation Promotion Association of CAS(CX2340007003)Technical Talent Promotion Plan(TS2021002).
文摘High-rate CO_(2)-to-CH_(4)photoreduction with high selectivity is highly attractive,which is a win-win strategy for mitigating the greenhouse effect and the energy crisis.However,the poor photocatalytic activity and low product selectivity hinder the practical application.To precisely tailor the product selectivity and realize high-rate CO_(2)photoreduction,we design atomically precise Pd species supported on In_(2)O_(3)nanosheets.Taking the synthetic 1.30Pd/In_(2)O_(3)nanosheets as an example,the aberration-correction high-angle annular dark-field scanning transmission electron microscopy image displayed the Pd species atomically dispersed on the In_(2)O_(3)nanosheets.Raman spectra and X-ray photoelectron spectra established that the strong interaction between the Pd species and the In_(2)O_(3)substrate drove electron transfer from In to Pd species,resulting in electron-enriched Pd sites for CO_(2)activation.Synchrotronradiation photoemission spectroscopy demonstrated that the Pd species can tailor the conduction band edge of In_(2)O_(3)nanosheets to match the CO_(2)-to-CH_(4)pathway,instead of the CO_(2)-to-CO pathway,which theoretically accounts for the high CH_(4)selectivity.Moreover,in situ X-ray photoelectron spectroscopy unveiled that the catalytically active sites had a change from In species to Pd species over the 1.30Pd/In_(2)O_(3)nanosheets.In situ FTIR and EPR spectra reveal the atomically precise Pd species with rich electrons prefer to adsorb the electrophilic protons for accelerating the*COOH intermediates hydrogenation into CH_(4).Consequently,the 1.30Pd/In_(2)O_(3)nanosheets reached CO_(2)-to-CH_(4)photoconversion with 100%selectivity and 81.2μmol g^(−1)h^(−1)productivity.
