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运用电化学暂态(电位阶跃)方法和时间分辨FTIR反射光谱研究甲酸在Pt电极上的解离吸附过程,揭示了这一表面分子过程的反应速率在-0.25至0.25VvsSCE区间呈火山形变化的规律,还测得在含10-3mol•L-1HCOOH的溶液中最大的初始解离速率(-0.06V时)为9.33×10-11mol•cm-2•s-1. 相似文献
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在分子束条件下利用化学发光技术研究了亚稳态惰性气体原子He(23S1)和Ne(3P0,2)与NH3碰撞的解离激发反应.He(23S1)与NH3的反应中观察到NH(A-X,c-a,c-b),NH+(B-X)和H*-Balmer发射.对NH(A-X,c-a)的谱图进行了拟合.分析NH(c-b)谱发现NH(c)倾向于生成具有f对称性的转动能级,NH3可能是经由一个NH2中间体分两步解离,这与121.6nm光解NH3时的倾向性正好相反.利用参比反应测得生成NH(A,c)的速度为k=1.0×10-11cm3•s-1.He(23S1)与NH3生成的NH(A,v’=1)的转动激发比v’=0时要高,根据含角动量守恒的相空间理论,其生成过程可能具有较大的解离半碰撞参数.Ne(3P0,2)与NH3反应只有NH(A-X,c-a)发射,NH(A,c)的振转布居可由简单相空间理论三体解离模式解释. 相似文献
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提出了“互联网+”背景下,“无机及分析化学”课程教学“一核心、二目标、三探索、四构建”的教学策略。实施结果表明,基于学生发展的课程核心知识,以“具有解决复杂制药工程、化工工程、材料工程的化学基础知识”“为学习后续课程打下坚实基础”2个具体教学目标为导向,通过开展综合实践活动、案例教学、课程思政等3种教学改革探索,构建线上线下有机衔接的立方书、立体化线上教学资源、线上线下混合型教学模式及过程和结果相融合的SPOC教学模式下的课程评价体系4种教学举措,能有效提高课程教学质量。 相似文献
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采用量子化学的密度泛甬理论方法,探讨了H2S、HS和S在立方ZrO2(110)面上不同吸附位的吸附情况.构型优化的结果表明:在bridge位H2S以垂直底物平面H原子向上、垂直底物平面H原子向下、平行底物平面和hollow位H2S平行底物平面模式吸附在ZrO2(110)面发生解离吸附.SH和S的最佳吸附位分别为桥位和顶位.Mulliken布局和态密度分析显示S原子的p轨道与Zr原子的d轨道发生相互作用.通过计算解离反应的能垒,表明H2S分子在立方ZrO2(110)面发生两步解离. 相似文献
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采用二级微扰理论(MP2)量子化学研究方法, 对C2H4-nFn···LiH (n=0, 1, 2)二聚体的结构和π锂键性质进行了分析. 结果表明氟原子的取代改变了乙烯分子的π电子云形状, 从而使二聚体体系中的π锂键发生偏移、伸长和弯曲. 通过与类似的π氢键体系C2H4-nFn···HF (n=0, 1, 2)比较, 发现π锂键在二级弱相互作用的影响下, 发生了明显的弯曲, 表现出弱的方向性. 在CCSD(T)/6-311++G(3df, 3pd)理论水平下, 二聚体的相互作用能强弱顺序为: 33.85 kJ·mol-1 (C2H4-LiH)>27.32 kJ·mol-1 (C2H3F-LiH)>21.34 kJ·mol-1 (cis-C2H2F2-LiH)>20.25 kJ·mol-1 (g-C2H2F2-LiH), 说明氟取代削减了乙烯分子与LiH之间的相互作用. 相似文献
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“互联网+”的理念使科普教育的形式更具多样化。讲述了高职院校开展化学科普教育的必要性;“互联网+”背景下化学科普教育的现状;以及基于互联网理念,通过制作科普动漫视频,开发科普小游戏,建立微信群等方式开展化学科普教育的实践,并总结了在实践中取得的成效。 相似文献
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利用水热反应模拟原始地球的水热环境, 以甘油和磷酸二氢铵为原料, 采用非生物手段合成了sn-甘油-1(3)-磷酸和甘油-2-磷酸2种磷酸酯类物质. 通过此反应, 无机磷进入生物分子形成了在生物体中起重要作用C—O—P键. 研究了反应温度、 反应时间及矿物催化剂对反应的影响. 在蒙脱土的催化下, C—O—P键的产率最大可达到1.15%(摩尔分数). 相似文献
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Magic number cluster ion Mn5+ and abundant Mn/O cluster ions havc been formed by 532nm laser ablation of MnCO3 solid sample with time-of-flight mass spectroscopy detection. The experimental results show that Mn5+ was formed in the cooler dilute tail region of the plume produced by laser ablation, while Mn/O cluster ions were mainly formed in the hotter dense preceding portion of the plume, they all were produced by postablation cluster growth in the ablation plume. Pentagonal with D(5h) symmetry is the possible structure of Mn5+, which is supported by our ab initio calculation. 相似文献
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C6H5
+ fragment ion produced from toluene,n-propylbenzene and acetophenone have been studied using an electron impact technique. The ionization efficiency data have
been treated by the inverse convolution first differential technique. First and higher appearance energies for ions produced
from the three precursors are reported. The heats of formation for the ions obtained at threshold from the three molecules
are calculated 相似文献
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原子簇化合物的合成方法,由于条件限制,只有B、C、St等非金属元素与过渡金属袈基化合物等较为成熟.贵金属原子簇的合成则较困难.然而,应用激光等离子体反应,可使周期表内几乎所有元素都生成原子簇,为原子簇的生成与研究提供了一条新途径.该方法生成的原子簇在飞行时间质谱仪上可记录到一系列信号,某些信号呈现区域极大(或被称为‘匈数’吵].郑兰芬等用纯化的红磷粉分别与金粉、银粉混合,在激光等离子作源飞行时间质谱仪上得到一系列谱图【2]:ig与P作用只得到单核xg与P形成的lgy:iE离子簇.谱图较简单,*沪X最大可达叱叱… 相似文献
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Jill Wisnewski Ferguson Timothy J. Dudley Kyle C. Sears Sally M. McIntyre Mark S. Gordon R.S. Houk 《Spectrochimica Acta Part B: Atomic Spectroscopy》2009,64(7):690-696
Several polyatomic ions in inductively coupled plasma–mass spectrometry are studied experimentally and by computational methods. Novel calculations based on spin-restricted open shell second order perturbation theory (ZAPT2) and coupled cluster (CCSD(T)) theory are performed to determine the energies, structures and partition functions of the ions. These values are combined with experimental data to evaluate a dissociation constant and gas kinetic temperature (Tgas) value. In our opinion, the resulting Tgas value can sometimes be interpreted to deduce the location where the polyatomic ion of interest is generated. The dissociation of N2H+ to N2+ leads to a calculated Tgas of 4550 to 4900 K, depending on the computational data used. The COH+ to CO+ system yields a similar temperature, which is not surprising considering the similar energies and structures of COH+ and N2H+. The dissociation of H2CO+ to HCO+ leads to a much lower Tgas (< 1000 to 2000 K). Finally, the dissociation of H2COH+ to HCOH+ generates a Tgas value between those from the other HxCO+ ions studied here. All of these measured Tgas values correspond to formation of extra polyatomic ion in the interface or extraction region. The computations reveal the existence of isomers such as HCO+ and COH+, and H2CO+ and HCOH+, which have virtually the same m/z values and need to be considered in the interpretation of results. 相似文献
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Emrys A. Jones Nicholas P. Lockyer John C. Vickerman 《International journal of mass spectrometry》2007,260(2-3):146
Recent developments in desorption/ionisation mass spectrometry techniques have made their application to biological analysis a realistic and successful proposition. Developments in primary ion source technology, mainly through the advent of polyatomic ion beams, have meant that the technique of secondary ion mass spectrometry (SIMS) can now access the depths of information required to allow biological imaging to be a viable option.Here the role of the primary ion C60+ is assessed with regard to molecular imaging of lipids and pharmaceuticals within tissue sections. High secondary ion yields and low surface damage accumulation are demonstrated on both model and real biological samples, indicating the high secondary ion efficiency afforded to the analyst by this primary ion when compared to other cluster ion beams used in imaging. The newly developed 40 keV C60+ ion source allows the beam to be focused such that high resolution imaging is demonstrated on a tissue sample, and the greater yields allow the molecular signal from the drug raclopride to be imaged within tissue section following in vivo dosing.The localisation shown for this drug alludes to issues regarding the chemical environment affecting the ionisation probability of the molecule; the importance of this effect is demonstrated with model systems and the possibility of using laser post-ionisation as a method for reducing this consequence of bio-sample complexity is demonstrated and discussed. 相似文献
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Michael MillerFrank J. Owens 《Chemical physics》2012,394(1):52-55
Density functional theory is used to calculate the bond dissociation energy to cleave the C60C60 bond of the paramagnetic X-C60C60-X and X-C60C60 dimers where X is F, OH, O and H. The results show that these dimers would not be stable much above room temperature and therefore cannot constitute the paramagnetic phase needed to form the observed ferromagnetism which has been shown to be stable up to 800 K. The calculated bond dissociation energies to remove an F, OH or H from a single C60 are large suggesting that they could be the source of the unpaired spin needed for the high temperature ferromagnetism. 相似文献
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Mano N Kamota M Inohana Y Yamaguchi S Goto J 《Analytical and bioanalytical chemistry》2006,386(3):682-688
Ion trap/time-of-flight hybrid mass spectrometers are powerful tools for the detailed structural analysis of modified peptides. We have analyzed Met-Lys-bradykinin modified with deoxycholate at the amino-terminus or the epsilon-amino group as model peptides. These two modified peptides produced fragment ions with the same nominal but different exact masses in tandem mass spectrometry with low-energy collision-induced dissociation. Accurate high-resolution analysis coupled with MS(3) allowed us to distinguish the deoxycholate modification sites in the modified peptides. 相似文献
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Somayyeh Rostamzadehmansor Shahriare Ghammamy Kheyrollah Mehrani 《Journal of fluorine chemistry》2008,129(8):674-679
The reaction of VOF3 with (C2H5)4NF, (CH3)4NCl and (C4H9)4NBr salts in anhydrous CH3CN produced new complexes with the anion general formula [VOF3X]− in that (X = F−, Cl−, Br−). These were characterized by elemental analysis, IR, UV/Visible and 19F NMR spectroscopy. The optimized geometries and frequencies of the stationary point are calculated at the B3LYP/6-311G level of theory. Theoretical results showed that the VX (X = F, Cl, Br) bond length values for the [VOF3X]− in compounds 1-3 are 1.8247, 2.4031 and 2.5595 Å, respectively. Also, the VF5 bond length values in [VOF3X]− are 1.824, 1.812 and 1.802 Å, respectively. These results reveal that the bond order for VX bonds decrease from compounds 1 to 3, while for VF5 bonds, the bond orders increase. It can be concluded that the decrease of VX bonds lengths and the increase of VF5 bond lengths in compounds 1-3 result from the increase of the hyperconjugation from compounds 1 to 3. Harmonic vibrational frequencies and infrared intensities for VOF4−, VOF3Cl− and VOF3Br− are studied by means of theoretical and experimental methods. The calculated frequencies are in reasonable agreement with the experiment values. These data can be used in models of phosphoryl transfer enzymes because vanadate can often bind to phosphoryl transfer enzymes to form a trigonal-bipyramidal structure at the active site. 相似文献