Terahertz beats of vibrational modes in methanol and ethanol selectively excited by tr-CARS technique  

作　　者：HE Ping WANG HuiLi FAN RongWei CHEN DeYing XIA YuanQin YU Xin WANG JiaLing JIANG YuGang 

机构地区：[1]College of Foundation Science,Harbin University of Commerce,Harbin 150028,China [2]National Key Laboratory of Science and Technology on Tunable Laser,Harbin Institute of Technology,Harbin 150080,China [3]Institute of Opto-electronics,Harbin Institute of Technology,Harbin 150080,China [4]Tianjin Key Laboratory of Optical Thin Films,Tianjin Jinhang Institute of Technical Physics,Tianjin 300192,China

出　　处：《Science China(Physics,Mechanics & Astronomy)》2012年第12期2351-2356,共6页中国科学：物理学、力学、天文学（英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 60878018 and 61008023);the Program of Excellentat Harbin Institute of Technology

摘　　要：A recently developed time-resolved coherent anti-Stokes Raman scattering(tr-CARS) technique allows the measurement of vibrational coherences with high frequency differences with the ambient environment.The method is based on the short spatial extension of femtosecond pulses with a broadband tunable nonlinear optical parametric amplifier(NOPA) and an internal time delay between the probe and pump/Stokes pulse pair in the CARS process.The different beat frequencies between Raman modes can be selectively detected as oscillations in the tr-CARS transient signal with the broadband tunable NOPA.In this work,we aim at the Raman C-H stretching vibrations from 2800 cm 1 to 3000 cm 1,within which the different vibrational modes in both ethanol and methanol are selectively excited and simultaneously detected.The high time resolution of the experimental set-up allows one to monitor the vibrational coherence dynamics and to observe the quantum beat phenomena on a terahertz scale.This investigation indicates that the femtosecond tr-CARS technique is a powerful tool for the real-time monitoring and detection of molecular and biological agents,including airborne contaminants such as bacterial spores,viruses and their toxins.A recently developed time-resolved coherent anti-Stokes Raman scattering（tr-CARS） technique allows the measurement of vibrational coherences with high frequency differences with the ambient environment.The method is based on the short spatial extension of femtosecond pulses with a broadband tunable nonlinear optical parametric amplifier（NOPA） and an internal time delay between the probe and pump/Stokes pulse pair in the CARS process.The different beat frequencies between Raman modes can be selectively detected as oscillations in the tr-CARS transient signal with the broadband tunable NOPA.In this work,we aim at the Raman C-H stretching vibrations from 2800 cm 1 to 3000 cm 1,within which the different vibrational modes in both ethanol and methanol are selectively excited and simultaneously detected.The high time resolution of the experimental set-up allows one to monitor the vibrational coherence dynamics and to observe the quantum beat phenomena on a terahertz scale.This investigation indicates that the femtosecond tr-CARS technique is a powerful tool for the real-time monitoring and detection of molecular and biological agents,including airborne contaminants such as bacterial spores,viruses and their toxins.

关 键 词：terahertz beat femtosecond TIME-RESOLVED CARS 

分 类 号：TN249[电子电信—物理电子学] TQ221.211[化学工程—有机化工]