It has been reported that electron-rotation coupling plays a significant role in diatomic nuclear dynamics induced by intense VUV pulses [Phys. Rev. A 102(2020) 033114;Phys. Rev. Res. 2(2020) 043348]. As a further ste...It has been reported that electron-rotation coupling plays a significant role in diatomic nuclear dynamics induced by intense VUV pulses [Phys. Rev. A 102(2020) 033114;Phys. Rev. Res. 2(2020) 043348]. As a further step, we present here investigations of the electron-rotation coupling effect in the presence of Auger decay channel for core-excited molecules, based on theoretical modeling of the total electron yield(TEY), resonant Auger scattering(RAS) and x-ray absorption spectra(XAS) for two showcases of CO and CH^(+) molecules excited by resonant intense x-ray pulses. The Wigner D-functions and the universal transition dipole operators are introduced to include the electron-rotation coupling for the core-excitation process. It is shown that with the pulse intensity up to 10^(16) W/cm^(2), no sufficient influence of the electron-rotation coupling on the TEY and RAS spectra can be observed. This can be explained by a suppression of the induced electron-rotation dynamics due to the fast Auger decay channel, which does not allow for effective Rabi cycling even at extreme field intensities,contrary to transitions in optical or VUV range. For the case of XAS, however, relative errors of about 10% and 30% are observed for the case of CO and CH^(+), respectively, when the electron-rotation coupling is neglected.It is concluded that conventional treatment of the photoexcitation, neglecting the electron-rotation coupling,can be safely and efficiently employed to study dynamics at the x-ray transitions by means of electron emission spectroscopy, yet the approximation breaks down for nonlinear processes as stimulated emission, especially for systems with light atoms.展开更多
Light penetration depth in biological tissue is limited by tissue scattering.Correcting scattering becomes particularly challenging in scenarios with limited photon availability and when access to the transmission sid...Light penetration depth in biological tissue is limited by tissue scattering.Correcting scattering becomes particularly challenging in scenarios with limited photon availability and when access to the transmission side of the scattering tissue is not possible.Here,we introduce,to our knowledge,a new two-photon microscopy system with Fourier-domain intensity coupling for scattering correction(2P-FOCUS).2P-FOCUS corrects scattering by intensity modulation in the Fourier domain,leveraging the nonlinearity of multiple-beam interference and twophoton excitation,eliminating the need for a guide star,iterative optimization,or measuring transmission or reflection matrices.2P-FOCUS uses random patterns to probe scattering properties,combined with a single-shot algorithm to rapidly generate the correction mask.2P-FOCUS can also correct scattering beyond the limitation of the memory effect by automatically customizing correction masks for each subregion in a large field-of-view.We provide several proof-of-principle demonstrations here,including focusing and imaging through a bone sample,and imaging neurons and cerebral blood vessels in the mouse brain ex vivo.2P-FOCUS significantly enhances two-photon fluorescence signals by several tens of folds compared to cases without scattering correction at the same excitation power.2P-FOCUS can also correct tissue scattering over a 230μm×230μm×510μm volume,which is beyond the memory effect range.2P-FOCUS is able to measure,calculate,and correct scattering within a few seconds,effectively delivering more light deep into the scattering tissue.2P-FOCUS could be broadly adopted for deep tissue imaging owing to its powerful combination of effectiveness,speed,and cost.展开更多
In this paper,a new theory about sound absorption by pseudostochastic diffusors is proposed. A quantity, 'coupling specific acoustic impedance' is defined for the coupling between adjacent wells of the structu...In this paper,a new theory about sound absorption by pseudostochastic diffusors is proposed. A quantity, 'coupling specific acoustic impedance' is defined for the coupling between adjacent wells of the structure. The variation of particle velocity and sound pressure in the vicinity of the opening of wells is investigated and the exact solution of lst approach is derived. Moreover, the nonlinear effect is discussed. The rigorous formula to calculate the nonlinear coupling specific acoustic impedance is derived. Typical calculation shows the nonlinear effect can apparently improve the sound absorption character of the structure even if the sound pressure level of incident wave is medial.展开更多
基金Supported by the National Natural Science Foundation of China (Grant Nos.11934004,11974230,and 11904192)the Education of Russian Federation (Grant No.FSRZ-2020-0008)。
文摘It has been reported that electron-rotation coupling plays a significant role in diatomic nuclear dynamics induced by intense VUV pulses [Phys. Rev. A 102(2020) 033114;Phys. Rev. Res. 2(2020) 043348]. As a further step, we present here investigations of the electron-rotation coupling effect in the presence of Auger decay channel for core-excited molecules, based on theoretical modeling of the total electron yield(TEY), resonant Auger scattering(RAS) and x-ray absorption spectra(XAS) for two showcases of CO and CH^(+) molecules excited by resonant intense x-ray pulses. The Wigner D-functions and the universal transition dipole operators are introduced to include the electron-rotation coupling for the core-excitation process. It is shown that with the pulse intensity up to 10^(16) W/cm^(2), no sufficient influence of the electron-rotation coupling on the TEY and RAS spectra can be observed. This can be explained by a suppression of the induced electron-rotation dynamics due to the fast Auger decay channel, which does not allow for effective Rabi cycling even at extreme field intensities,contrary to transitions in optical or VUV range. For the case of XAS, however, relative errors of about 10% and 30% are observed for the case of CO and CH^(+), respectively, when the electron-rotation coupling is neglected.It is concluded that conventional treatment of the photoexcitation, neglecting the electron-rotation coupling,can be safely and efficiently employed to study dynamics at the x-ray transitions by means of electron emission spectroscopy, yet the approximation breaks down for nonlinear processes as stimulated emission, especially for systems with light atoms.
文摘Light penetration depth in biological tissue is limited by tissue scattering.Correcting scattering becomes particularly challenging in scenarios with limited photon availability and when access to the transmission side of the scattering tissue is not possible.Here,we introduce,to our knowledge,a new two-photon microscopy system with Fourier-domain intensity coupling for scattering correction(2P-FOCUS).2P-FOCUS corrects scattering by intensity modulation in the Fourier domain,leveraging the nonlinearity of multiple-beam interference and twophoton excitation,eliminating the need for a guide star,iterative optimization,or measuring transmission or reflection matrices.2P-FOCUS uses random patterns to probe scattering properties,combined with a single-shot algorithm to rapidly generate the correction mask.2P-FOCUS can also correct scattering beyond the limitation of the memory effect by automatically customizing correction masks for each subregion in a large field-of-view.We provide several proof-of-principle demonstrations here,including focusing and imaging through a bone sample,and imaging neurons and cerebral blood vessels in the mouse brain ex vivo.2P-FOCUS significantly enhances two-photon fluorescence signals by several tens of folds compared to cases without scattering correction at the same excitation power.2P-FOCUS can also correct tissue scattering over a 230μm×230μm×510μm volume,which is beyond the memory effect range.2P-FOCUS is able to measure,calculate,and correct scattering within a few seconds,effectively delivering more light deep into the scattering tissue.2P-FOCUS could be broadly adopted for deep tissue imaging owing to its powerful combination of effectiveness,speed,and cost.
文摘In this paper,a new theory about sound absorption by pseudostochastic diffusors is proposed. A quantity, 'coupling specific acoustic impedance' is defined for the coupling between adjacent wells of the structure. The variation of particle velocity and sound pressure in the vicinity of the opening of wells is investigated and the exact solution of lst approach is derived. Moreover, the nonlinear effect is discussed. The rigorous formula to calculate the nonlinear coupling specific acoustic impedance is derived. Typical calculation shows the nonlinear effect can apparently improve the sound absorption character of the structure even if the sound pressure level of incident wave is medial.
