莫嘉雯,黄自谦,袁颖,吕鑫茹,韦相忠

• 1:广西中医药大学药学院

摘要(Abstract)：

超强超短激光发展的大趋势是激光脉冲时间越来越短,功率越来越高,两者之间是否存在关联?本文采用分子动力学方法模拟太赫兹脉冲宽度逐渐变窄时对水分子加热的影响,作用时间内保证脉冲能量和光子频率不变(频率为15THz),近似于一个固定冲激强度的冲激函数。模拟结果表明,脉冲的半高宽从2ps变化到0.2ps时,除了统计上的误差外,对水分子的加热效果影响不大。然而,当脉冲的半高宽从100fs减小到50fs时,加热效果突然急剧减小。这可以用单位冲激函数的性质及共振原理来说明。因为光子频率为15THz,其周期是67fs,50fs刚好进入太赫兹脉冲频率周期内,这样破坏了水分子的共振响应,可以看作脉冲时间上的阈值效应。

关键词(KeyWords)： 太赫兹脉冲;分子模拟;水分子;阈值效应

Abstract:

Keywords:

基金项目(Foundation): 国家自然科学基金资助项目(71461002)

作者(Author): 莫嘉雯,黄自谦,袁颖,吕鑫茹,韦相忠

参考文献(References)：

• [1]CASALBUONI S,Schmidt B,Schmuser P,Arsov V,and Wesch S.Ultrabroadband terahertz source and beamline based on coherent transition radiation[J].Phys.Rev.Spec.Top-AC,2009,12:030705．
• [2]HERZER S,GOPAL A,SCHMIDT A,et al.Observation of gigawatt-class THz pulses from a compact laser-driven particle a ccelerator[J].Phys.Rev.Lett,2013,111:074802．
• [3]NAROZHNY N B,FEDOTOV A M.Creation of electron-positron plasma with superstrong laser field[J].Eur.Phys.J.Special Topics,2014,223,1083-1092．
• [4]MAKAROV V A,PEREZHOGIN I A,POTRAVKIN N N.Few-cycle solitary wave formation from elliptically polarized ultrashort Laser pulse in a medium with frequency dispersion[J].Optics Communications,2015,339:228-235．
• [5]BRAUN A,KRILLKE R F,FRENTZEN M,et al.Heat generation caused by ablation of dental hard tissues with an ultrashort pulse laser(USPL)system[J].Lasers Med.Sci.2015,30:475-481．
• [6]MULLER N.Kinetics of micelle dissociation by temperaturejump techniques.reinterpretation[J].J.Phys.Chem,1972,76:3017-3020．
• [7]RIGLER R,RABL C,JOVIN T M.A temperature jump apparatus for fluorescence measurements[J].Rev.Sci.Instrum,1974,45:580-588．
• [8]周晓蓉，王毅，黄豪中．纳米流体在散热器管中的传热模拟[J]．广西大学学报，2017,42(6):1985-1992．
• [9]MA H,WAN C,WU A,ZEWAIL A H.DNA folding and melting observed in real time redefine the energy landscape[J].Proc.Natl.Acad.Sci.U.S.A,2007,104:712716．
• [10]MA H,WAN C,ZEWAIL A H.Dynamics of ligand substitution in labile cobalt complexes resolved by ultrafast T-jump[J].Proc.Nat.Acad.Sci,2008,105:12754 12757．
• [11]HUSE N,ASHIHARA S,NIBBERING E T,ELSAESSER T.Ultrafast vibrational relaxation of O-H bendingand librational excitations in liquid H2O[J].Chem.Phys.Lett,2005,404:389-393．
• [12]MISHRA P K,VENDRELL O,SANTRA R.Ultrafast energy transfer from solvent to solute induced by subpicosecond highly intense THz pulses[J].J.Phys.Chem.B 2015,119:8080-8086．
• [13]WERNET P,GAVRILA G,GODEHUSEN K,et al.Ultrafast temperature jump in liquid water studied by a novel infrared pump-X-ray probe technique[J].Appl.Phys.A,Mater.Sci.Process,2008,92:511-516．
• [14]MISHRA P K,VENDRELL O,SANTRA R.Ultrafast energy transfer to liquid water by sub-picosecond high-intensity terahertz pulses:An ab initio molecular dynamics study[J].Angew.Chem.Int.Ed,2013,52:13685-C1368．
• [15]HUANG Z Q,YANG R Y,JIANG W Z,ZHANG Q L.Heating of nanosized liquid water in high-intensity terahertz pulses[J].CHIN.PHYS.LETT,2016,33(1):013101.