We present a fully time-dependent quantum wave packet evolution method for investigating molecular dynamics in intense laser fields.This approach enables the simultaneous treatment of interactions among multiple elect...We present a fully time-dependent quantum wave packet evolution method for investigating molecular dynamics in intense laser fields.This approach enables the simultaneous treatment of interactions among multiple electronic states while simultaneously tracking their time-dependent electronic,vibrational,and rotational dynamics.As an illustrative example,we consider neutral H_(2)molecules and simulate the laser-induced excitation dynamics of electronic and rotational states in strong laser fields,quantitatively distinguishing the respective contributions of electronic dipole transitions(within the classical-field approximation)and non-resonant Raman processes to the overall molecular dynamics.Furthermore,we precisely evaluate the relative contributions of direct tunneling ionization from the ground state and ionization following electronic excitation in the strong-field ionization of H_(2).The developed methodology shows strong potential for performing high-precision theoretical simulations of electronic-vibrational-rotational state excitations,ionization,and dissociation dynamics in molecules and their ions under intense laser fields.展开更多
It is shown that when relativistically intense ultrashort laser pulses are reflected from the boundary of a plasma with a near-critical density,the Doppler frequency shift leads to generation of intense radiation in b...It is shown that when relativistically intense ultrashort laser pulses are reflected from the boundary of a plasma with a near-critical density,the Doppler frequency shift leads to generation of intense radiation in both the high-frequency(up to the x-ray)and low-frequency(mid-infrared)ranges.The efficiency of energy conversion into the wavelength range above 3μm can reach several percent,which makes it possible to obtain relativistically intense pulses in the mid-infrared range.These pulses are synchronized with high harmonics in the ultraviolet and x-ray ranges,which opens up opportunities for high-precision pump–probe measurements,in particular,laser-induced electron diffraction and transient absorption spectroscopy.展开更多
Atomic models of high-Zmulticharged ions are extremely complex and require experimental validation.Oneway to do so is to crosscheck the predicted wavelengths of resonance transitions in He-and Li-like ions against pre...Atomic models of high-Zmulticharged ions are extremely complex and require experimental validation.Oneway to do so is to crosscheck the predicted wavelengths of resonance transitions in He-and Li-like ions against precise spectroscopic measurements that use the spectral lines of H-like ions for spectra calibration;these reference data can be modeled with outstanding precision.However,for elements with Z of at least 15,it is quite difficult to create a hot dense plasma with a large concentration ofH-like charge states.To mitigate this issue,the suggestion here is to use as laser targets particular minerals comprising elements with moderate(between 15 and 30)and low(less than 15)Z,with emission from the latter delivering perfect reference lines over a whole range o fHe-and Li-like moderate-Z emission under examination.This approach is implemented to measure the wavelengths of resonance transitions(1snp→1s^(2) for n=2,3)in He-likeKions and their dielectronic satellites by irradiating plates of orthoclase(KAlSi_(3)O_(8))with0.5-kJ subnanosecond laser pulses.X-ray spectra of the laser-generated plasma contain the investigated lines of highly charged K-ions together with precisely known reference lines of H-like Al and Si atoms.The K-shell spectral line wavelengths are measured with a precision of around 0.3 mA.展开更多
A simple idea to obtain a desired color that hiding the black color, and the visibility of tubes and corrugations of the metal sheet （absorber） of the thermal solar collectors which is consider the main obstacle to ...A simple idea to obtain a desired color that hiding the black color, and the visibility of tubes and corrugations of the metal sheet （absorber） of the thermal solar collectors which is consider the main obstacle to facade integration buildings of solar thermal collectors will be presented in this study by designing a multilayer optical interference filter during RF magnetron sputtering process. This filter work as antireflection coating in the near IR region and also includes a high colored reflectance at a specific wavelength in the visible region, this is to gain an esthetic aspect for the thermal solar collector which can be used as building facades by employing appropriate dielectric materials with high refractive index （H） like SiO2 and low refractive index （L） such as MgF2 which they deposited on glass substrate for quarterwave thickness and for the optical model air//HL//glass.展开更多
Attributed to the intense development and complexity in electronic devices,energy dissipation is becoming more essential nowadays.The carbonaceous materials particularly graphene(Gr)-based thermal interface materials(...Attributed to the intense development and complexity in electronic devices,energy dissipation is becoming more essential nowadays.The carbonaceous materials particularly graphene(Gr)-based thermal interface materials(TIMs)are exceptional in heat management.However,because of the anisotropic behavior of Gr in composites,the TIMs having outstanding through-plane thermal conductivity(┴TC)are needed to fulfill the upcoming innovation in numerous devices.In order to achieve this,herein,nano-urethane linkage-based modified Gr and carbon fibers architecture termed as nanourethane linkage(NUL)-Gr/carbon fibers(CFs)is fabricated.Wherein,toluene diisocyanate is utilized to develop a novel but simple NUL to shape a new interface between graphene sheets.Interestingly,the prepared composite of NUL-Gr/CFs with polyvinylidene fluoride matrix shows outstanding performance in heat management.Owing to the unique structure of NUL-Gr/CFs,an unprecedented value of┴TC(~7.96 W·m^–1·K^–1)is achieved at a low filler fraction of 13.8 wt.%which translates into an improvement of^3,980%of pristine polymer.The achieved outcomes elucidate the significance of the covalent interaction between graphene sheets as well as strong bonding among graphene and matrix in the composites and manifest the potential of proposed NUL-Gr/CFs architecture for practical applications.展开更多
Ultrafine-grained tungsten(UFG W) produced by severe plastic deformation technology has many potential applications due to its high strength and ductility. To reveal the mechanism for the high ductility of UFG W, the ...Ultrafine-grained tungsten(UFG W) produced by severe plastic deformation technology has many potential applications due to its high strength and ductility. To reveal the mechanism for the high ductility of UFG W, the deformation and failure behaviors of coarse-grained tungsten(CG W) and UFG W have been compared based on a three-dimensional crystal plastic finite element method(CPFEM) simulation. Cohesive element method has been utilized to model the behavior of grain boundaries(GBs). Both plastic deformation in grain interiors and grain boundary opening have been observed in different periods of deformation in UFG W. It is concluded that the high GB density and elongated microstructure in the UFG W suppress crack propagation, decrease the stress concentration and impurity concentration on GBs, therefore enhance the ductility of the material.展开更多
The post-compression technique based on self-phase modulation of high-energy pulses leads to an increase in achievable peak power and intensity.Typically,the pulses considered in experiments have been less than 100 fs...The post-compression technique based on self-phase modulation of high-energy pulses leads to an increase in achievable peak power and intensity.Typically,the pulses considered in experiments have been less than 100 fs in duration.Here,the method is applied to the ELFIE laser system at the LULI facility,for a pulse of 7 J energy and an initial measured duration of 350 fs.A 5-mm-thick fused silica window and a 2 mm cyclic-olefin polymer were used as optical nonlinear materials.The 9 cm diameter beam was spectrally broadened to a bandwidth corresponding to 124 fs Fourier-limited pulse duration,and then it was partly post-compressed to 200 fs.After measuring the spatial spectra of the beam fluence,a uniform gain factor of 4 increase in the fluctuations over the studied range of frequencies is observed,due to small-scale self-focusing.展开更多
In this research, the effects of target sputtering power on the structure and optical properties of radio frequency （RF） sputtered Ti6A14V films were investigated. Different sputtering RF powers were used to produce...In this research, the effects of target sputtering power on the structure and optical properties of radio frequency （RF） sputtered Ti6A14V films were investigated. Different sputtering RF powers were used to produce different thicknesses of Ti6A14V thin films, From the X-ray diffraction, it was found that the Ti6A14V films had polycrystalline cubic and hexagonal structures and increased films crystallinity and crystalline size with increasing the sputtering power. Atomic forces microscopy （AFM） gave us a nanometric film character, films homogeneity, and surfaces roughness. A higher degree of roughness and average grain size with increasing RF power was exhibited. Band gap and refractive index of Ti6A14V thin films varied with sputtering RF powers.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2022YFA1602502)the National Natural Science Foundation of China(Grant No.12450404)。
文摘We present a fully time-dependent quantum wave packet evolution method for investigating molecular dynamics in intense laser fields.This approach enables the simultaneous treatment of interactions among multiple electronic states while simultaneously tracking their time-dependent electronic,vibrational,and rotational dynamics.As an illustrative example,we consider neutral H_(2)molecules and simulate the laser-induced excitation dynamics of electronic and rotational states in strong laser fields,quantitatively distinguishing the respective contributions of electronic dipole transitions(within the classical-field approximation)and non-resonant Raman processes to the overall molecular dynamics.Furthermore,we precisely evaluate the relative contributions of direct tunneling ionization from the ground state and ionization following electronic excitation in the strong-field ionization of H_(2).The developed methodology shows strong potential for performing high-precision theoretical simulations of electronic-vibrational-rotational state excitations,ionization,and dissociation dynamics in molecules and their ions under intense laser fields.
基金supported by the Ministry of Science and Higher Education of the Russian Federation,state assignment for the Lobachevsky University of Nizhny Novgorod,Project No.0729-2020-0035state assignment for the Institute of Applied Physics RAS,Project No.0030-2021-0012.
文摘It is shown that when relativistically intense ultrashort laser pulses are reflected from the boundary of a plasma with a near-critical density,the Doppler frequency shift leads to generation of intense radiation in both the high-frequency(up to the x-ray)and low-frequency(mid-infrared)ranges.The efficiency of energy conversion into the wavelength range above 3μm can reach several percent,which makes it possible to obtain relativistically intense pulses in the mid-infrared range.These pulses are synchronized with high harmonics in the ultraviolet and x-ray ranges,which opens up opportunities for high-precision pump–probe measurements,in particular,laser-induced electron diffraction and transient absorption spectroscopy.
基金The reported study was funded by RFBR,project number 19-32-60050the Ministry of Education,Youth,and Sports of the Czech Republic[Project No.LM2018114(PALS Infrastructure)]it was conducted within the framework of the State Assignment of the Ministry of Science and Higher Education to JIHT RAS.
文摘Atomic models of high-Zmulticharged ions are extremely complex and require experimental validation.Oneway to do so is to crosscheck the predicted wavelengths of resonance transitions in He-and Li-like ions against precise spectroscopic measurements that use the spectral lines of H-like ions for spectra calibration;these reference data can be modeled with outstanding precision.However,for elements with Z of at least 15,it is quite difficult to create a hot dense plasma with a large concentration ofH-like charge states.To mitigate this issue,the suggestion here is to use as laser targets particular minerals comprising elements with moderate(between 15 and 30)and low(less than 15)Z,with emission from the latter delivering perfect reference lines over a whole range o fHe-and Li-like moderate-Z emission under examination.This approach is implemented to measure the wavelengths of resonance transitions(1snp→1s^(2) for n=2,3)in He-likeKions and their dielectronic satellites by irradiating plates of orthoclase(KAlSi_(3)O_(8))with0.5-kJ subnanosecond laser pulses.X-ray spectra of the laser-generated plasma contain the investigated lines of highly charged K-ions together with precisely known reference lines of H-like Al and Si atoms.The K-shell spectral line wavelengths are measured with a precision of around 0.3 mA.
文摘A simple idea to obtain a desired color that hiding the black color, and the visibility of tubes and corrugations of the metal sheet （absorber） of the thermal solar collectors which is consider the main obstacle to facade integration buildings of solar thermal collectors will be presented in this study by designing a multilayer optical interference filter during RF magnetron sputtering process. This filter work as antireflection coating in the near IR region and also includes a high colored reflectance at a specific wavelength in the visible region, this is to gain an esthetic aspect for the thermal solar collector which can be used as building facades by employing appropriate dielectric materials with high refractive index （H） like SiO2 and low refractive index （L） such as MgF2 which they deposited on glass substrate for quarterwave thickness and for the optical model air//HL//glass.
基金the Nature Science Associate Foundation(NSAF)(No.U1730103)the National Natural Science Foundation of China(NSFC)(No.11672002)。
文摘Attributed to the intense development and complexity in electronic devices,energy dissipation is becoming more essential nowadays.The carbonaceous materials particularly graphene(Gr)-based thermal interface materials(TIMs)are exceptional in heat management.However,because of the anisotropic behavior of Gr in composites,the TIMs having outstanding through-plane thermal conductivity(┴TC)are needed to fulfill the upcoming innovation in numerous devices.In order to achieve this,herein,nano-urethane linkage-based modified Gr and carbon fibers architecture termed as nanourethane linkage(NUL)-Gr/carbon fibers(CFs)is fabricated.Wherein,toluene diisocyanate is utilized to develop a novel but simple NUL to shape a new interface between graphene sheets.Interestingly,the prepared composite of NUL-Gr/CFs with polyvinylidene fluoride matrix shows outstanding performance in heat management.Owing to the unique structure of NUL-Gr/CFs,an unprecedented value of┴TC(~7.96 W·m^–1·K^–1)is achieved at a low filler fraction of 13.8 wt.%which translates into an improvement of^3,980%of pristine polymer.The achieved outcomes elucidate the significance of the covalent interaction between graphene sheets as well as strong bonding among graphene and matrix in the composites and manifest the potential of proposed NUL-Gr/CFs architecture for practical applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.11632001,11521202)the Science Challenge Project(Grant No.TZ2018001)the ENN Science and Technology Development Co.,Ltd.(Grant No.9710L2018-001)
文摘Ultrafine-grained tungsten(UFG W) produced by severe plastic deformation technology has many potential applications due to its high strength and ductility. To reveal the mechanism for the high ductility of UFG W, the deformation and failure behaviors of coarse-grained tungsten(CG W) and UFG W have been compared based on a three-dimensional crystal plastic finite element method(CPFEM) simulation. Cohesive element method has been utilized to model the behavior of grain boundaries(GBs). Both plastic deformation in grain interiors and grain boundary opening have been observed in different periods of deformation in UFG W. It is concluded that the high GB density and elongated microstructure in the UFG W suppress crack propagation, decrease the stress concentration and impurity concentration on GBs, therefore enhance the ductility of the material.
基金This work was supported by the Center of Excellence‘Center of Photonics’,Ministry of Science and Higher Education of the Russian Federation(contract No.075-15-2020-906)Project ELI-RO 16/2020 SBUF funded by the Institute for Atomic Physics(IFA)and by the Council for Doctoral Studies(CSUD),University of Bucharest.
文摘The post-compression technique based on self-phase modulation of high-energy pulses leads to an increase in achievable peak power and intensity.Typically,the pulses considered in experiments have been less than 100 fs in duration.Here,the method is applied to the ELFIE laser system at the LULI facility,for a pulse of 7 J energy and an initial measured duration of 350 fs.A 5-mm-thick fused silica window and a 2 mm cyclic-olefin polymer were used as optical nonlinear materials.The 9 cm diameter beam was spectrally broadened to a bandwidth corresponding to 124 fs Fourier-limited pulse duration,and then it was partly post-compressed to 200 fs.After measuring the spatial spectra of the beam fluence,a uniform gain factor of 4 increase in the fluctuations over the studied range of frequencies is observed,due to small-scale self-focusing.
文摘In this research, the effects of target sputtering power on the structure and optical properties of radio frequency （RF） sputtered Ti6A14V films were investigated. Different sputtering RF powers were used to produce different thicknesses of Ti6A14V thin films, From the X-ray diffraction, it was found that the Ti6A14V films had polycrystalline cubic and hexagonal structures and increased films crystallinity and crystalline size with increasing the sputtering power. Atomic forces microscopy （AFM） gave us a nanometric film character, films homogeneity, and surfaces roughness. A higher degree of roughness and average grain size with increasing RF power was exhibited. Band gap and refractive index of Ti6A14V thin films varied with sputtering RF powers.
