This paper reports that a one-colour fs pump probe measurement has been carried out for studying photoionization/photodissociation of cyclohexanone （C6H10O） in intense laser field. Two of the fragments from eyclohex...This paper reports that a one-colour fs pump probe measurement has been carried out for studying photoionization/photodissociation of cyclohexanone （C6H10O） in intense laser field. Two of the fragments from eyclohexanone, C2H＋ and C3H3＋, are studied under 800 nm laser pump-probe and the results obtained show similar time evolutions. It proposes a feasible model for analysing the experimental observations of the one-colour fs pump-probe measurement. The results demonstrate that as an intermediate product, the excited molecular parent ions play a very important role in photionization/photodissociation processes in intense laser field.展开更多
In this work,we simulated 2D infrared spectroscopy(IR)spectroscopy in both transmission geometry and Brewster-angle reflection geometry.Light dispersion and the leakage of s-polarized light are considered in simulatin...In this work,we simulated 2D infrared spectroscopy(IR)spectroscopy in both transmission geometry and Brewster-angle reflection geometry.Light dispersion and the leakage of s-polarized light are considered in simulating the enhancement factor of the reflection mode.Our simulation shows that the dispersion in reflection will only alter the 2D IR lineshape slightly and can be corrected.Leaking spolarized light due to imperfectness of IR polarizers in the reflection geometry may limit the enhancement factor,but such limit is above what a typical experiment can reach.In the current experiment,the enhancement factor is mainly limited by the precision of incident angle,for which ordinary rotation stages are probably not adequate enough.Moreover,traditional energy ratio of pump and probe pulses,which is 9:1,may not be ideal and could be changed to 2:1 in the reflection geometry.Considering all the above factors,the enhancement on the order of 1000 is possible in the current experiment.Nevertheless,near-Brewster angle reflection will enhance both the signal and the noise caused by the signal itself,therefore this method only works if the noise is unrelated to the signal,particularly if the noise is caused by the fluctuation in the probe.It cannot improve the signal to noise ratio when the dominate noise is from the signal itself.The theoretical results here agree reasonably well with published experiment results and pave way for realizing even higher enhancement at nearer-Brewster angle.展开更多
We present new diagnostics for use in optical laser pump-X-ray Free Electron Laser(XFEL)probe experiments to monitor dimensions,intensity profile and focusability of the XFEL beam and to control initial quality and ho...We present new diagnostics for use in optical laser pump-X-ray Free Electron Laser(XFEL)probe experiments to monitor dimensions,intensity profile and focusability of the XFEL beam and to control initial quality and homogeneity of targets to be driven by optical laser pulse.By developing X-ray imaging,based on the use of an LiF crystal detector,we were able to measure the distribution of energy inside a hard X-ray beam with unprecedented high spatial resolution(~1 mm)and across a field of view larger than some millimetres.This diagnostic can be used in situ,provides a very high dynamic range,has an extremely limited cost,and is relatively easy to be implemented in pump-probe experiments.The proposed methods were successfully applied in pump-probe experiments at the SPring-8 Angstrom Compact free electron LAser(SACLA)XFEL facility and its potential was demonstrated for current and future High Energy Density Science experiments.展开更多
Femtosecond laser-induced periodic surface structures(LIPSS)have been extensively studied over the past few decades.In particular,the period and groove width of high-spatial-frequency LIPSS(HSFL)is much smaller than t...Femtosecond laser-induced periodic surface structures(LIPSS)have been extensively studied over the past few decades.In particular,the period and groove width of high-spatial-frequency LIPSS(HSFL)is much smaller than the diffraction limit,making it a useful method for efficient nanomanufacturing.However,compared with the low-spatial-frequency LIPSS(LSFL),the structure size of the HSFL is smaller,and it is more easily submerged.Therefore,the formation mechanism of HSFL is complex and has always been a research hotspot in this field.In this study,regular LSFL with a period of 760 nm was fabricated in advance on a silicon surface with two-beam interference using an 800 nm,50 fs femtosecond laser.The ultrafast dynamics of HSFL formation on the silicon surface of prefabricated LSFL under single femtosecond laser pulse irradiation were observed and analyzed for the first time using collinear pump-probe imaging method.In general,the evolution of the surface structure undergoes five sequential stages:the LSFL begins to split,becomes uniform HSFL,degenerates into an irregular LSFL,undergoes secondary splitting into a weakly uniform HSFL,and evolves into an irregular LSFL or is submerged.The results indicate that the local enhancement of the submerged nanocavity,or the nanoplasma,in the prefabricated LSFL ridge led to the splitting of the LSFL,and the thermodynamic effect drove the homogenization of the splitting LSFL,which evolved into HSFL.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No 10534010)
文摘This paper reports that a one-colour fs pump probe measurement has been carried out for studying photoionization/photodissociation of cyclohexanone （C6H10O） in intense laser field. Two of the fragments from eyclohexanone, C2H＋ and C3H3＋, are studied under 800 nm laser pump-probe and the results obtained show similar time evolutions. It proposes a feasible model for analysing the experimental observations of the one-colour fs pump-probe measurement. The results demonstrate that as an intermediate product, the excited molecular parent ions play a very important role in photionization/photodissociation processes in intense laser field.
基金supported by the National Natural Science Foundation of China(No.21973102,No.21573243,and No.21327802)。
文摘In this work,we simulated 2D infrared spectroscopy(IR)spectroscopy in both transmission geometry and Brewster-angle reflection geometry.Light dispersion and the leakage of s-polarized light are considered in simulating the enhancement factor of the reflection mode.Our simulation shows that the dispersion in reflection will only alter the 2D IR lineshape slightly and can be corrected.Leaking spolarized light due to imperfectness of IR polarizers in the reflection geometry may limit the enhancement factor,but such limit is above what a typical experiment can reach.In the current experiment,the enhancement factor is mainly limited by the precision of incident angle,for which ordinary rotation stages are probably not adequate enough.Moreover,traditional energy ratio of pump and probe pulses,which is 9:1,may not be ideal and could be changed to 2:1 in the reflection geometry.Considering all the above factors,the enhancement on the order of 1000 is possible in the current experiment.Nevertheless,near-Brewster angle reflection will enhance both the signal and the noise caused by the signal itself,therefore this method only works if the noise is unrelated to the signal,particularly if the noise is caused by the fluctuation in the probe.It cannot improve the signal to noise ratio when the dominate noise is from the signal itself.The theoretical results here agree reasonably well with published experiment results and pave way for realizing even higher enhancement at nearer-Brewster angle.
基金The XFEL experiments were performed at the BL3 of SACLA with the approval of the Japan Synchrotron Radiation Research Institute(JASRI)(Proposals Nos.2014A8045,and 2014B8068)This research was partially supported by grants from Grants-in-Aid for Scientific Research(Kakenhi Grant Nos.15H02153 and 17K05729)+1 种基金the Core-to-Core Program on International Alliance for Material Science in Extreme States with High Power Laser of the Japan Society for the Promotion of Science(JSPS),from the X-ray Free Electron Laser Priority Strategy Program of the MEXT,contract 12005014,and within the state assignment of FASO of Russia(theme N01201357846)The part of work was supported by the Agence Nationale de la Recherche in the frame of the ANR project TurboHEDP(ANR-15-CE30-0011).
文摘We present new diagnostics for use in optical laser pump-X-ray Free Electron Laser(XFEL)probe experiments to monitor dimensions,intensity profile and focusability of the XFEL beam and to control initial quality and homogeneity of targets to be driven by optical laser pulse.By developing X-ray imaging,based on the use of an LiF crystal detector,we were able to measure the distribution of energy inside a hard X-ray beam with unprecedented high spatial resolution(~1 mm)and across a field of view larger than some millimetres.This diagnostic can be used in situ,provides a very high dynamic range,has an extremely limited cost,and is relatively easy to be implemented in pump-probe experiments.The proposed methods were successfully applied in pump-probe experiments at the SPring-8 Angstrom Compact free electron LAser(SACLA)XFEL facility and its potential was demonstrated for current and future High Energy Density Science experiments.
基金supports from the National Natural Science Foundation of China(12074123,12174108)the Foundation of‘Manufacturing beyond limits’of Shanghai‘Talent Program'of Henan Academy of Sciences.
文摘Femtosecond laser-induced periodic surface structures(LIPSS)have been extensively studied over the past few decades.In particular,the period and groove width of high-spatial-frequency LIPSS(HSFL)is much smaller than the diffraction limit,making it a useful method for efficient nanomanufacturing.However,compared with the low-spatial-frequency LIPSS(LSFL),the structure size of the HSFL is smaller,and it is more easily submerged.Therefore,the formation mechanism of HSFL is complex and has always been a research hotspot in this field.In this study,regular LSFL with a period of 760 nm was fabricated in advance on a silicon surface with two-beam interference using an 800 nm,50 fs femtosecond laser.The ultrafast dynamics of HSFL formation on the silicon surface of prefabricated LSFL under single femtosecond laser pulse irradiation were observed and analyzed for the first time using collinear pump-probe imaging method.In general,the evolution of the surface structure undergoes five sequential stages:the LSFL begins to split,becomes uniform HSFL,degenerates into an irregular LSFL,undergoes secondary splitting into a weakly uniform HSFL,and evolves into an irregular LSFL or is submerged.The results indicate that the local enhancement of the submerged nanocavity,or the nanoplasma,in the prefabricated LSFL ridge led to the splitting of the LSFL,and the thermodynamic effect drove the homogenization of the splitting LSFL,which evolved into HSFL.
基金This work is by the National Natural Science Foundation of China(No.22203006,No.21927901,No.92261206,No.21627805,No.12174012,No.21673004,No.21821004,No.21674001,and No.21790363)Ministry of Science and Technology of China(a special talent program)and the Beijing City.
