碰撞反应Ca+C2H5Br和Ca+nC3H7Br产物CaBr的内能态分布

采用准经典轨线方法研究了碰撞反应Ca+C2H5Br和Ca+nC3H7Br产物CaBr的内能态分布,计算了产物分子CaBr的平均振动、转动和平动能量以及总可资用能量.结果表明,当碰撞能为7.54kJ/mol时,产物的能量主要为振动能量;随着碰撞能增加,产物的平动能和转动能增加,而振动能略微减小,最可几振动态向较低振动能级移动;反应物分子内能态分布对产物分子的内能态分布影响很小;反应基团越大,产物的振动能占总可资用能量的比例就越高.碰撞反应Ca+C2H5Br和Ca+nC3H7Br均存在两条竞争的反应路径迁移相碰和直接反应路径.前者产生高振动激发态产物CaBr,后者引起C-Br键断裂.当碰撞能增加时,两种反应均倾向于后者.     

H2SiCl2 中 SiH 伸缩振动的泛频光谱

在2000 ～ 9000 波数 、 12000 ～12900 波数的光谱区间记录了室温下H2SiCl2气体分子的振动泛频光谱，所用的仪器分别是高分辨傅立叶变换光谱仪和高灵敏激光腔内吸收光谱仪。用局域模模型和包含达林－丹尼生共振的简正模模型，归属了SiH伸缩振动的基频和泛频，振动量子数的改变△VSiH=1, 2, 3, 4 and 6。通过对实验能级的非线性拟合，得到SiH伸缩振动的谐振频率ωm、非谐性常数χm、键间耦合系数λ、莫尔斯振子参数 De、α 和相互作用力常数 。实验发现，随着振动能量的增加，振动簇（manifold，两个SiH键的伸缩振动量子数m+n=常数 ）中能量最低的两个能级的间距逐渐减小。当△VSiH≥4时，在实验误差范围内这两个最低的振动态能级简并。这种简并的能级结构类似双原子莫尔斯振子，符合Birge-Sponer 关系。双原子莫尔斯振子直接描述了H2SiCl2分子中SiH 的高泛频伸缩振动，表明在高振动情况下振动能量已经集中到单个SiH键上。     

不同能量的氦原子与同位素分子H2(D2,T2)碰撞分波截面的理论计算

用Tang-Toennies势模型和密耦近似方法计算了不同能量下惰性气体原子He与H2及其同位素D2,T2替代碰撞体系的振转激发碰撞截面.通过分析He-H2(D2,T2)各碰撞体系分波截面的差异,总结出在H2分子的对称同位素替代情形下He-H2(D2,T2)碰撞体系分波截面随量子数和体系约化质量变化的规律.结果表明,体系的约化质量及入射原子相对碰撞能量的变化均给体系的碰撞截面带来不同程度的影响.     

H原子与CO2分子碰撞的化学反应与能量转移

用时间分辨傅立叶红外发射光谱的方法对H原子与CO2分子的碰撞动力学进行了实验研究．用紫外激光光解的方法分别制备出三个不同平动能为174．7、241．0和306．2 kJ／mol的氢原子,并引发H CO2→OH CO反应．观察到了反应的产物,即振动激发的CO (v≤2)．同时也看到了在H原子与CO2分子的碰撞中发生高效的T- V能量转移．CO2的反对称伸缩模的最高振动能级为v=4．化学反应与能量转移的速率之比大约为10．     

H2在Li掺杂Al7C+上吸附的理论研究

摘要: 利用密度泛函理论研究了H2分子在Li掺杂Al7C+团簇上的吸附．对于Al7C+团簇,H2分子的吸附能仅为-0.017eV,掺杂Li原子到Al7C+团簇可以明显增强对H2分子的吸附．吸附一个H2分子时吸附能可以达到-0.151eV,吸附四个H2分子的平均吸附能为-0.073eV．根据自然键轨道分析,电荷从Li原子向Al7C+团簇转移,带正电的Li离子极化H2分子并且增强了H2分子与Al7CLi+团簇之间的相互作用．     

3He4He与H2分子碰撞的同位素效应研究

用公认精确度较高的密耦近似方法计算了入射能量E=0.5eV时惰性气体原子3He(4He)与H2分子替代碰撞体系的转动激发碰撞截面.通过分析3He(4He)-H2碰撞体系分波截面和微分截面的差异,总结出在氦原子的同位素替代情形下3He(4He)-H2碰撞体系分波截面和微分截面随分波数增加和同位素原子质量改变的变化规律.     

Z状顺磁性化合物[{Cu(bipy)[C6H4(COO)2]}2·H2O]n和[Cu(phen)[C6H4(COO)2]]n的分子振动光谱研究

用分子振动光谱对已合成的具有顺磁性的化合物 [{Cu(bipy) [C6H4(COO) 2 ]} 2 ·H2 O]n(Ⅰ )和 [Cu( phen) [C6H4(COO) 2 ]]n(Ⅱ )进行深入研究 ,推测它们的结构 ,并将得到的结果与X射线晶体衍射测定的结构进行比较。文章对化合物的红外、拉曼光谱进行归属 ,还讨论了分子振动光谱与结构的关系     

H2O分子OH键振动能谱的代数计算

用U(2)代数模型,对H2O分子OH键的高激发振动能谱进行了理论计算,并与其它模型的计算相比较,结果表明,代数模型能以较小的标准偏差描述这一分子OH键的振动能谱。     

RbH(X1∑+,v=O～2)能级与H2碰撞振动能量转移

利用积分时间分辨荧光光谱方法,研究了RbH(X1∑+,v=0～2)与H2间的振动碰撞能量转移.在Rb-H2混合样品池中,泵浦激光双光子激发Rb原子至6D态,Rb(6D)与H2反应生成RbH(x1∑+)分子,探测激光延迟泵浦激光20 ns,通过激光感应荧光光谱(LIF)的测量,确定了X1∑+(v=0～2,J)原生态的转动...     

激光烧蚀Al热原子与CF4,CCl4,CH2Br2反应中激发态C2的形成

脉冲激光烧蚀平面铝靶产生的热原子与气相CF4,CCl4,CH2Br2的碰撞反应中,在430～600nm之间观测到激发态C2分子的发光光谱,它们可归属为Swan带的d^3Ⅱg=a^3Ⅱu跃迁中△v=2,1,0,-1,-2五个振动序列(v′≤6)。谱强度分析表明,C2激发态可很好的用热平衡描述,其振动温度达6000K左右。同时在△v=0和-1的振动带间观测到振荡的谱峰,它们是转动谱线叠加的结果。激光烧蚀Al产生的等离子体在膨胀中产生的激波及其本身的动能与反应气体碰撞使其解离产生C,然后复合形成C2。C2激发态d可能是通过激发态的Al(^2S)经近共振传能产生,也不排除在有足够碰撞能下优先形成C2激发态b,再通过与d态的v′=6能级交叉无辐射跃迁而进入d态。     

Vibrational spectra of H2O and CF4 molecules using Lie algebraic approach

In this paper, we introduce one dimensional vibron model to analyze the fundamental, overtone and combination modes of CF₄ molecule and both stretching, bending vibrational mode of bent H₂O molecule up to first overtone with few algebraic parameters. Using the model Hamiltonian, we reported here better results for the vibrational spectra of H₂O. Our analysis suggests some reassignments of levels and predicts location of states in case of CF₄ molecule which was not yet observed.     

Ion-electron coincidence study of the thermal He(23S) + H2 Penning reaction

A new Penning-electron-Penning-ion coincidence method is described. It is applied to the study of the thermal reaction of He(2³S) with H₂. The main results reported are separate electron energy spectra that are coincident with the three different ions formed: HeH₂⁺, HeH⁺ and H₂⁺. Based on these results it is shown that the Penning reaction of the He(2³S)/H ₂ system proceeds in two well-separated steps: (i) ionization at distances R (HeH₂) ? 6a₀ in which H₂⁺ (v) is formed in different vibrational states; and (ii) reactive collision of H₂⁺ (v) with He. For the second step the variation of the branching ratios with vibrational quantum numbers v = 0 to v = 10 is derived, and it is shown that these branching ratios may be regarded as relative vibrational-energy-dependent cross-sections for the collision of H₂⁺ (v) with He at an average relative kinetic energy of ～20 meV.     

激光诱导荧光法研究CH2Cl2分子的振动能量转移

本文中用激光诱导荧光法首次研究了有机分子CH₂Cl₂分子的振动能量转移。实验测得了CH₂Cl₂分子的ν₃和ν₃/ν₉振动模的激活和消激活速率常数,以及稀有气体分子对CH₂Cl₂分子的ν₃/ν₉振动模消激活的影响。用SSH理论计算了CH₂Cl₂-稀有气体碰撞,CH₂Cl₂分子ν₃/ν₉的V-T能量转移相对几率,分析讨论了CH₂Cl₂分子的振动能量转移的通道。 关键词：     

O~++H_2→OH~++H反应的动力学研究

采用含时量子波包方法结合二阶分裂算符传播子对初始态为(v=0, j=0)的O~++H_2→OH~++H反应体系在0.01—1.00 eV的碰撞能范围内进行了态分辨理论水平上的动力学计算.对反应概率、积分截面、微分截面以及固定初始态的热速率常数等动力学信息进行了计算并与文献报道的实验和理论结果进行了比较.结果表明本文的理论结果与实验结果十分符合.从微分截面的散射信息可知,在低碰撞能范围内,插入反应机制在反应中占据主导地位.随着碰撞能的增加,反应机制逐渐由插入机制变为抽取反应机制.     

Characteristics of multiple-photon dissociation of OsO4 molecule by two frequency tunable CO2-laser pulses

Using two-frequency technique for the multiple photon dissociation of OsO₄ molecule by IR laser radiation, the following new results have been obtained: 1. the narrow resonances of multiple photon absorption on few low lying vibrational transitions have been found in the dissociation yield as a function of exciting frequency ν₁; 2. the structure of the dissociation yield as a function of dissociating frequency ν₂ connected with high lying vibrational transition has been studied; 3. the kinetic of the vibration relaxation of high vibrationally excited molecules was investigated; 4. the unimolecular character of the multiple photon dissociation of OsO₄ has been proved.     

Total cross sections for scattering of electrons from O2, H2O, H2, O3, CO and CO2 at 100－2000eV

A complex optical model potential rewritten by the concept of bonded atom, which considers the overlap of electron clouds, is employed to calculate the total cross sections for electron scattering from several simple molecules (O_2, H_2O, H_2, O_3, CO and CO_2) consisting of C, H and O atoms in an incident energy range of 100－2000eV by the use of the additivity rule at Hartree－Fock level. In the study, the complex optical potential composed of static, exchange, correlation polarization plus absorption contributions firstly uses the bonded-atom concept. The quantitative molecular total cross section results are compared with experimental data and with the other calculations wherever available and good agreement is obtained. It is shown that the additivity rule along with the complex optical model potential rewritten by the concept of bonded atom can be used successfully to calculate the total cross section of electron－molecule scattering above 100eV, whereas the rule together with the complex optical model potential not rewritten by the concept of bonded atom is only successfully used above 300－500eV. So, the introduction of the bonded-atom concept in the complex optical potential can improve the accuracy of the total cross section calculations.     

The effect of temperature on collision induced intersystem crossing in the reaction of CH2 with H2

Laser flash photolysis of ketene at 308 nm, coupled with H atom vacuum ultraviolet laser induced fluorescence, was used to determine the branching ratio for the CH₃ + H channel (1a) in the reaction of CH₂¹A₁ (¹CH₂) with H₂, over the temperature range 300–500 K. This reaction channel competes with collision induced intersystem crossing (CIISC) to form triplet methylene, CH₂³B₁ (³CH₂) (channel 1b). The branching ratio for H formation, k_1a/k₁, was determined by measuring the relative H atom yield in three time resolved measurements of H: (i) in ketene, H₂ mixtures, where H is exclusively formed by reaction 1a, (ii) in ketene, H₂, NO mixtures ([NO] [H₂]), where H is formed at short times by 1a and at longer times by ³CH₂ + NO, following 1b, and (iii) in ketene, He, NO mixtures ([NO] [He]), where H is exclusively formed from ³CH₂ + NO, following deactivation of singlet to triplet methylene by He. k_1a/k₁ was found to increase from 0.85 at 300 K to unity at 500 K, with the yield of CIISC decreasing from 0.15 to zero. This is the first measurement of the temperature dependence of the rate coefficient for CIISC in a reactive system. The rate coefficient for CIISC with an inert gas increases with T. It has been suggested that the fractional yield of CIISC will increase with temperature in reactive systems, thus reducing the rate coefficient for reaction at high temperature, with significant consequences for combustion systems. The present experiments demonstrate that this is not the case for reaction with H₂ and implies a different CIISC mechanism for reactive vs inert collision partners.     

Li修饰的C$lt;sub$gt;6$lt;/sub$gt;分子对H$lt;sub$gt;2$lt;/sub$gt;O的吸附研究

采用密度泛函理论中的广义梯度近似研究C₆Li吸附H₂O分子并将之进行分解的催化过程. 几何优化发现：Li原子最稳定的吸附位置是位于C 原子顶位上方. 研究表明,第一个H₂O 分子吸附在C₆Li上需要克服1.77 eV的能量势垒,然后分解为H和OH且与Li原子成键. 当吸附第二个H₂O分子时,第二个H₂O分子需要克服1.2 eV的能量势垒分解为H和OH,其中H与Li原子上的H原子结合成H₂,OH则替代Li 原子上的H结合在Li原子上. 因此C₆Li 可以作为催化剂将H₂O分子进行分解得到H₂. 分析可知：C₆Li主要是通过Li原子与H₂O之间形成的偶极矩作用来吸附H₂O 分子,与C₆₀Li₁₂ 的储氢机制类似. 研究结果可为储氢材料的制备提供一个新的思路. 关键词： 6')" href="#">C₆ Li 2O')" href="#">H₂O 密度泛函理论     

Electron impact ionization of Ar n , (H2O) n , Ar n (H2O) m clusters

Signals from ions forming in a supersonic molecular beam consisting of an argon-water vapor mixture are measured as functions of the exciting electron energy in the range to 120 eV. The thresholds of electron impact excitation of (H₂O) _{n − 1}H⁺ and Ar _n (H₂O _m ⁺ clusters are determined for the first time. It is found that the proton-hydroxyl group binding energy decreases considerably both in the case of water molecule clustering and when mixed Ar _n (H₂O) _m clusters arise.