Ethylene, the simplest model of a carbon-carbon double bond system, is pivotal in numerous chemical and biological processes. By employing intense infrared laser pump-probe techniques alongside coincidence measurement...Ethylene, the simplest model of a carbon-carbon double bond system, is pivotal in numerous chemical and biological processes. By employing intense infrared laser pump-probe techniques alongside coincidence measurements, we investigate the ultrafast non-adiabatic dynamics involved in the breakage of carbon-carbon double bonds and hydrogen elimination in dissociation of ethylene. Our study entails analyzing the dynamic kinetic energy release spectra to assess three bond-breaking scenarios, movements of nuclei, and structural changes around the carbon atoms. This allows us to evaluate the relaxation dynamics and characteristics of various dissociative states. Notably, we observe a significant rise in the yield of fragments resulting from C–H bond breakage with the delay time extended, suggesting non-adiabatic coupling through conical intersections from C–C bond breakage as a probable cause.展开更多
Topological insulator materials,including Bi_(2)Te_(3),Sb_(2)Te_(3),Sb_(2)Te_(3),and Bi_(2)Se_(3),have attracted some attention due to their narrow band gaps,high carrier mobility,wide spectral absorption ranges and o...Topological insulator materials,including Bi_(2)Te_(3),Sb_(2)Te_(3),Sb_(2)Te_(3),and Bi_(2)Se_(3),have attracted some attention due to their narrow band gaps,high carrier mobility,wide spectral absorption ranges and other characteristics.We report a new multi-compound topological insulator material BiSbTeSe_(2) that,compared with the traditional topological insulator composed of two elements,can integrate the physical advantages of each element,helpful to build an experimental platform with rich physical properties.The nonlinear optical characteristics of the quaternary material BiSbTeSe_(2) is obtained in the erbium-doped fiber laser.Using the BiSbTeSe_(2) as a saturable absorber material,the passive Q-switched and mode-locked fiber lasers are achieved.The pulse duration and signal-to-noise ratio(SNR)of the Q-switched fiber laser are 854 ns and 70 dB,respectively.Meanwhile,the pulse duration and SNR of the mode-locked fiber laser are 259 fs and 87.75 dB,respectively.This work proves that the BiSbTeSe_(2) has a considerable application prospect as a saturable absorber in fiber lasers,and provides a new reference for selection of high-performance saturable absorber materials.展开更多
In past decades,cellular networks have raised the usage of spectrum resources due to the victory of mobile broadband services.Mobile devices create massive data than ever before,facing the way cellular networks are in...In past decades,cellular networks have raised the usage of spectrum resources due to the victory of mobile broadband services.Mobile devices create massive data than ever before,facing the way cellular networks are installed pre-sently for satisfying the increased traffic requirements.The development of a new exclusive spectrum offered to meet up the traffic requirements is challenging as spectrum resources are limited,hence costly.Cognitive radio technology is pre-sented to increase the pool of existing spectrum resources for mobile users via Femtocells,placed on the top of the available macrocell network for sharing the same spectrum.Nevertheless,the concurrent reuse of spectrum resources from Femto networks poses destructive interference on macro networks.To resolve this issue,this paper introduces an optimal channel allocation model using the Oppo-sitional Beetle Swarm Optimization Algorithm(OBSOA)to allocate the channel with interference avoidance.A new OBSOA is derived in this paper by the inclu-sion of opposition-based learning(OBL)in BSOA.This algorithm allocates the channels used by PUs(PUs)to the secondary users(SUs)in such a way that inter-ference is minimized.This proposed approach is implemented in the MATrix LABoratory(MATLAB)platform.The performance of this proposed approach is evaluated in terms of several measures and the experimental outcome verified the superior nature of the OBSOA-based channel allocation model.OBSOA mod-el has resulted in a maximum signal-to-interference-plus-noise ratio value of 86.42 dB.展开更多
We design a set of processing devices to drill the shaped holes of turbine blades by using a femtosecond laser which outputs 1064 nm 5 W pulses at 100 kHz,investigate the mechanism of the femtosecond laser interaction...We design a set of processing devices to drill the shaped holes of turbine blades by using a femtosecond laser which outputs 1064 nm 5 W pulses at 100 kHz,investigate the mechanism of the femtosecond laser interaction with metals,and demonstrate that ultrafast laser drilling has distinct strong points against electric spark and longer laser pulse processing.The advantages related to no recast layer,no thermal effect,no micro crack,high precision,and high processing efficiency are carried out.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 12134005, 92261201, and 12274179)。
文摘Ethylene, the simplest model of a carbon-carbon double bond system, is pivotal in numerous chemical and biological processes. By employing intense infrared laser pump-probe techniques alongside coincidence measurements, we investigate the ultrafast non-adiabatic dynamics involved in the breakage of carbon-carbon double bonds and hydrogen elimination in dissociation of ethylene. Our study entails analyzing the dynamic kinetic energy release spectra to assess three bond-breaking scenarios, movements of nuclei, and structural changes around the carbon atoms. This allows us to evaluate the relaxation dynamics and characteristics of various dissociative states. Notably, we observe a significant rise in the yield of fragments resulting from C–H bond breakage with the delay time extended, suggesting non-adiabatic coupling through conical intersections from C–C bond breakage as a probable cause.
基金the Beijing Natural Science Foundation(Grant No.JQ21019)the National Natural Science Foundation of China(Grant Nos.12075034 and 11974003)。
文摘Topological insulator materials,including Bi_(2)Te_(3),Sb_(2)Te_(3),Sb_(2)Te_(3),and Bi_(2)Se_(3),have attracted some attention due to their narrow band gaps,high carrier mobility,wide spectral absorption ranges and other characteristics.We report a new multi-compound topological insulator material BiSbTeSe_(2) that,compared with the traditional topological insulator composed of two elements,can integrate the physical advantages of each element,helpful to build an experimental platform with rich physical properties.The nonlinear optical characteristics of the quaternary material BiSbTeSe_(2) is obtained in the erbium-doped fiber laser.Using the BiSbTeSe_(2) as a saturable absorber material,the passive Q-switched and mode-locked fiber lasers are achieved.The pulse duration and signal-to-noise ratio(SNR)of the Q-switched fiber laser are 854 ns and 70 dB,respectively.Meanwhile,the pulse duration and SNR of the mode-locked fiber laser are 259 fs and 87.75 dB,respectively.This work proves that the BiSbTeSe_(2) has a considerable application prospect as a saturable absorber in fiber lasers,and provides a new reference for selection of high-performance saturable absorber materials.
文摘In past decades,cellular networks have raised the usage of spectrum resources due to the victory of mobile broadband services.Mobile devices create massive data than ever before,facing the way cellular networks are installed pre-sently for satisfying the increased traffic requirements.The development of a new exclusive spectrum offered to meet up the traffic requirements is challenging as spectrum resources are limited,hence costly.Cognitive radio technology is pre-sented to increase the pool of existing spectrum resources for mobile users via Femtocells,placed on the top of the available macrocell network for sharing the same spectrum.Nevertheless,the concurrent reuse of spectrum resources from Femto networks poses destructive interference on macro networks.To resolve this issue,this paper introduces an optimal channel allocation model using the Oppo-sitional Beetle Swarm Optimization Algorithm(OBSOA)to allocate the channel with interference avoidance.A new OBSOA is derived in this paper by the inclu-sion of opposition-based learning(OBL)in BSOA.This algorithm allocates the channels used by PUs(PUs)to the secondary users(SUs)in such a way that inter-ference is minimized.This proposed approach is implemented in the MATrix LABoratory(MATLAB)platform.The performance of this proposed approach is evaluated in terms of several measures and the experimental outcome verified the superior nature of the OBSOA-based channel allocation model.OBSOA mod-el has resulted in a maximum signal-to-interference-plus-noise ratio value of 86.42 dB.
基金the National Special Fund of China for the Development of Major Research Equipment and Instruments under Grant No 2011YQ120075.
文摘We design a set of processing devices to drill the shaped holes of turbine blades by using a femtosecond laser which outputs 1064 nm 5 W pulses at 100 kHz,investigate the mechanism of the femtosecond laser interaction with metals,and demonstrate that ultrafast laser drilling has distinct strong points against electric spark and longer laser pulse processing.The advantages related to no recast layer,no thermal effect,no micro crack,high precision,and high processing efficiency are carried out.
