Na_(2)高振动态与CO_(2)间碰撞转移概率分布的实验测量  

Experimental Collisional Energy Transfer Distributions for Collisions of CO_(2) With Highly Vibrationally Excited Na_2

作　　者：王淑英[1] 尤德昌 马文佳 杨若凡 张仰志 於子雷 赵小芳 沈异凡[1] WANG Shu-ying;YOU De-chang;MA Wen-jia;YANG Ruo-fan;ZHANG Yang-zhi;YU Zi-lei;ZHAO Xiao-fang;SHEN Yi-fan(Xinjiang Key Laboratory of Solid State Physics and Devices,School of Physical Science and Technology,Xinjiang University,Urumqi 830017,China)

机构地区：[1]新疆大学物理科学与技术学院,新疆固态物理与器件重点实验室,新疆乌鲁木齐830017

出　　处：《光谱学与光谱分析》2023年第6期1760-1764,共5页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(12164047);新疆维吾尔自治区自然科学基金项目(2018D01C048);新疆大学大学生创新训练计划项目(XJU-SRT-21039);新疆大学横向项目(202102140005)资助。

摘　　要：受激发射泵浦激发Na_(2)至Na_(2)(ν″=30,J″=11)和Na_(2)(ν″=45,J″=11)。Na_(2)(ν″)与CO_(2)碰撞,研究了CO_(2)(00~00)的全态可分辨转动分布及不同的Na_(2)振动能对碰撞猝灭动力学的影响。光学吸收法测量Na_(2)(ν″)与CO_(2)碰撞后的弛豫过程,在一次碰撞的条件下,确定了ν″,ν″-1及ν″-2各振动能级上的转动态分布,而高于ν″的振动能级没有观察到,从而得到碰撞过程中Na_(2)转动能的改变。在碰撞发生1μs后,测量CO_(2)低J态的瞬时线轮廓,利用双Guass函数拟合,得到两个Doppler增宽轮廓,一个是存在于J态粒子的Doppler半宽,一个是被碰撞出J态粒子的Doppler半宽。从存在于J态的Doppler半宽,得到在Na_(2)(ν″)/CO_(2)碰撞中质心平移速度,从而确定平均平移能的增加〈ΔE_(rel)〉。Na_(2)(ν″)振动能的增加与CO_(2)平动能的增加有很大关系,Na_(2)振动能增加35%,而平动能增加56%。从CO_(2)的其他转动态碰到J态的出现速率系数k^(J)_(app)由测量碰撞前和碰撞1μs后的泛频激光感应荧光强度得到总的出现速度系数k_(app)=Σ_(J)k_(app)^(J)=(6.6±1.5)×10^(-10)cm^(3)·molecule^(-1)·s^(-1)[对Na_(2)(ν″=30)]和(5.9±1.3)×10^(-10) cm^(3)·molecule^(-1)·s^(-1)[对Na_(2)(ν″=45)]。因此Na_(2)(ν″)/CO_(2)的碰撞频率对Na_(2)的振动能不是很敏感的。取k_(app)作为参考速率系数,得到了全部能量转移概率分布P(ΔE),这里的ΔE包括了CO_(2)转动能和平动能的变化以及Na_(2)转动能的变化,对于Na_(2)分子振动能的较小增加,会引起P(ΔE)曲线的迅速增宽,在ΔE>500 cm^(-1)以后,Na_(2)(ν″=30)/CO_(2)的P(ΔE)曲线移到了Na_(2)(ν″=45)/CO_(2)的P(ΔE)曲线的下面。P(ΔE)对ΔE在0~3 000 cm^(-1)之间的数值积分给出〈ΔE〉_(trans)=590 cm^(-1)[对Na_(2)(ν″=30)],而对Na_(2)(ν″=45)则给出〈ΔE〉_(trans)=880 cm^(-1)。The full state-resolved distribution of scattered CO_(2)(0000)molecules from collisions with highly vibrationally excited Na 2(ν″=30 and 45)is reported and investigated how internal energy content impacts the dynamics for collisional quenching of high energy molecules.Stimulated emission pumping was used to excite the Na 2(ν″=30,J=11)and Na 2(ν″=45,J=11).Under single-collision conditions,rotational levels of the vibrationally relaxed Na 2(ν″-1)and Na 2(ν″-2)are identified.Levels attributable to upward vibrational transfer could not be observed.The change in Na 2 rotational energy was determined.Quantifying the simultaneous population change for low J states is accomplished by transient line profile measurements for individual states.The line width is a measure of the translational energy spread of the scattered molecules and the area under the line profile is a measure of the J-specific population.The nascent translational temperature T pres(for presence)and T dep(for depletion)are determined from the measured line widthsΔνpres andΔνdep,respectively.The presence line widthsΔνpres were obtained by fitting the double-Gaussian function to the transient line profile data at t=1μs.The lab-frame translational temperature T pres for the presence of scattered CO_(2) molecules and the relative(center-of-mass frame)translational temperatures T rel for Na 2(ν″)/CO_(2) collisions were determined based onΔνpres measurements.Average translational energy gains for the presence of CO_(2)(0000,J)following collisions with vibrationally excited Na 2 are determined using〈E rel〉=3/2 k(T rel-T cell).The comparison shows that the Na 2 vibrational energy that goes into the translational energy of the CO_(2) strongly depends on the initial energy:the translational energy of the J-specific collision pruducts increases by 56%or more for a 35%increase in donor vibrational energy.The appearance rate constants for individual CO_(2) rotational states are determined.The total appearance rate constant for Na 2(ν�

关 键 词：碰撞能量转移 激光诱导荧光 瞬时线轮廓 速率系数 能量增加分布函数 Na_(2)高振动激发态 CO_(2) 

分 类 号：O561.5[理学—原子与分子物理]