It is proved that the chemical reaction induced by femtosecond laser filament in the atmosphere produces CO,HCN,and NO,and the production CO and HCN are observed for the first time.The concentrations of the products a...It is proved that the chemical reaction induced by femtosecond laser filament in the atmosphere produces CO,HCN,and NO,and the production CO and HCN are observed for the first time.The concentrations of the products are measured by mid-infrared tunable laser absorption spectroscopy.In the reduced pressure air,the decomposition of CO_(2) is enhanced by vibration excitation induced by laser filament,resulting in the enhanced production of CO and HCN.At the same time,the CO and HCN generated from the atmosphere suffer rotation excitation induced by laser filament,enhancing their absorption spectra.It is found that NO,CO,and HCN accumulate to 134 ppm,80 ppm,and 1.6 ppm in sealed air after sufficient reaction time.The atmospheric chemical reaction induced by laser filament opens the way to changing the air composition while maintaining environmental benefits.展开更多
We investigate N_(2)^(+) air lasing at 391 nm,induced by strong laser fields in a nitrogen glow discharge plasma.We generate forward N_(2)^(+) air lasing on the B^(2)Σ_(u)^(+)(v’=0)-X^(2)Σ_(g)^(+)(v"=0) transi...We investigate N_(2)^(+) air lasing at 391 nm,induced by strong laser fields in a nitrogen glow discharge plasma.We generate forward N_(2)^(+) air lasing on the B^(2)Σ_(u)^(+)(v’=0)-X^(2)Σ_(g)^(+)(v"=0) transition at 391 nm by irradiating an intense 35-fs,800-nm laser in a pure nitrogen gas,finding that the 391-nm lasing quenches when the nitrogen gas is electrically discharged.In contrast,the 391-nm fluorescence measured from the side of the laser beam is strongly enhanced,demonstrating that this discharge promotes the population in the B^(2)Σ_(u)^(+)(v’=0) state.By comparing the lasing and fluorescence spectra of the nitrogen gas obtained in the discharged and laser-induced plasma,we show that the quenching of N_(2)^(+) lasing is caused by the efficient suppression of population inversion between the B^(2)Σ_(u)^(+) and X^(2)Σ_(g)^(+) states of N_(2)^(+),in which a much higher population occurs in the X^(2)Σ_(g)^(+) state in the discharge plasma.Our results clarify the important role of population inversion in generating N_(2)^(+) air lasing,and also indicate the potential for the enhancement of N_(2)^(+) lasing via further manipulation of the population in the X^(2)Σ_(g)^(+) state in the discharged medium.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.1625501 and 62027822)the Research Funds of Happiness Flower ECNU,China(Grant No.2021ST2110).
文摘It is proved that the chemical reaction induced by femtosecond laser filament in the atmosphere produces CO,HCN,and NO,and the production CO and HCN are observed for the first time.The concentrations of the products are measured by mid-infrared tunable laser absorption spectroscopy.In the reduced pressure air,the decomposition of CO_(2) is enhanced by vibration excitation induced by laser filament,resulting in the enhanced production of CO and HCN.At the same time,the CO and HCN generated from the atmosphere suffer rotation excitation induced by laser filament,enhancing their absorption spectra.It is found that NO,CO,and HCN accumulate to 134 ppm,80 ppm,and 1.6 ppm in sealed air after sufficient reaction time.The atmospheric chemical reaction induced by laser filament opens the way to changing the air composition while maintaining environmental benefits.
基金the National Natural Science Foundation of China(Grant Nos.61625501 and 62027822)the Open Fund of the State Key Laboratory of High Field Laser Physics(SIOM)。
文摘We investigate N_(2)^(+) air lasing at 391 nm,induced by strong laser fields in a nitrogen glow discharge plasma.We generate forward N_(2)^(+) air lasing on the B^(2)Σ_(u)^(+)(v’=0)-X^(2)Σ_(g)^(+)(v"=0) transition at 391 nm by irradiating an intense 35-fs,800-nm laser in a pure nitrogen gas,finding that the 391-nm lasing quenches when the nitrogen gas is electrically discharged.In contrast,the 391-nm fluorescence measured from the side of the laser beam is strongly enhanced,demonstrating that this discharge promotes the population in the B^(2)Σ_(u)^(+)(v’=0) state.By comparing the lasing and fluorescence spectra of the nitrogen gas obtained in the discharged and laser-induced plasma,we show that the quenching of N_(2)^(+) lasing is caused by the efficient suppression of population inversion between the B^(2)Σ_(u)^(+) and X^(2)Σ_(g)^(+) states of N_(2)^(+),in which a much higher population occurs in the X^(2)Σ_(g)^(+) state in the discharge plasma.Our results clarify the important role of population inversion in generating N_(2)^(+) air lasing,and also indicate the potential for the enhancement of N_(2)^(+) lasing via further manipulation of the population in the X^(2)Σ_(g)^(+) state in the discharged medium.
