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利用同步辐射光电离质谱结合理论计算, 研究了异亮氨酸的真空紫外光诱导电离解离.在光子能量为13 eV的质谱中探测到了m/z=86、75、74、69、57、46、45、44、41、30、28、18的碎片离子.对于异亮氨酸的主要碎片离子为:C5H12N+ (m/z=86)、C2H5NO4+ (m/z=75)、C5H9+ (m/z=69)、C4H9+(m/z=57)和CH4N+(m/z=30).由光电离效率曲线得到出现势分别为:8.84±0.07、9.25±0.06、10.20±0.12、9.25±0.10、11.05±0.07 eV.结合量化理论计算(B3LYP/6-31++G(d,p)),详细给出了它们可能的生成路径.这些解离通道包括简单的键断裂反应和涉及中间体、过渡态的反应,实验值和理论计算的离子出现能或势垒一致. 相似文献
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本文利用自主研制的反射式飞行时间质谱仪结合177.3 nm深紫外激光研究了苯和苯胺分子的光电离与光解离过程. 质谱实验发现苯在177.3 nm皮秒激光作用下发生高效电离并观测到不对称C-C键解离形成的以C4H3+为主的较小碎片峰. 相比之下,苯胺的深紫外光电离中主要产生一个C5H6+·离子自由基和一个较小丰度的C6H6+·碎片,分别对应于CNH分子和NH自由基的去除. 结合第一性原理计算,诠释了苯和苯胺这两个仅有一个氨基差异的分子光解离路径,揭示苯和苯胺分子中氢原子转移对于C-C或C-N键断裂的关键重要作用. 相似文献
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利用具有同步辐射源的反射式飞行时间质谱仪,研究甲基环己烷的真空紫外光电离和光解离. 观测到母体离子C7H14+和碎片离子C7H13+,C6H11+,C6H10+,C5H10+,C5H9+,C4H8+,C4H7+和C3H5+的光电离效率曲线. 测定甲基环己烷的电离能为9.80±0.03 eV,通过光电离效率曲线确定其碎片离子的出现势. 在B3LYP/6-31G(d)水平上对过渡态、中间体和产物离子的优化结构进行表征,并使用G3B3方法计算其能量. 提出主要碎片离子的形成通道. 分子内氢迁移和碳开环是甲基环己烷裂解途径中最重要的过程. 相似文献
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本文介绍了真空紫外光电离质谱结合理论计算研究环戊酮单分子的光电离解离过程. 在9.0∽15.5 eV能量范围内,测量了环戊酮离子及其碎片离子的光电离效率曲线. 通过光电离效率曲线,将环戊酮分子的电离能确定为9.23±0.03 eV,并确认碎片离子为:C5H7O+,C4H5O+,C4H8+,C3H3O+,C4H6+,C2H4O+,C3H6+,C3H5+,C3H4+,C3H3+,C2H5+, C2H4+. 利用量子化学计算方法,在ωB97X-D/6-31+G(d,p)理论水平基础上,提出了C5H8O+的解离机制. 通过对环戊酮解离路径的分析,发现开环和氢迁移过程为环戊酮离子解离的主要路径. 相似文献
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利用同步辐射真空紫外光电离质谱和理论计算对中性酪胺和多巴胺分子的光诱导解离过程进行研究.在较低光子能量下,通过近阈光电离仅得到母体离子信号.当增加光子能量到11.7 eV甚至更高时,从酪胺和多巴胺分别得到四个清晰可辨的碎片离子信号.另外通过测量母体离子的光电离效率曲线,酪胺和多巴胺分子的电离能分别为7.98和7.67 eV(实验误差为±0.05 eV).结合理论计算建立这两个分子的详细碎裂路径,包括相似的胺乙基消除路径.其中碎片C7H8O2+·(m/z=124)和C7H8O+·(m/z=108)的生成认为来自McLafferty重排,该过程经历分子内的γ氢迁移诱导的β开裂反应.
另外,C7-C8键直接开裂可以生成CH2NH2+(m/z=30)碎片离子,并且该过程和McLafferty重排为主要的裂解路径. 相似文献
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Data on the absorption coefficient of H2O in binary mixture with N2 in UV region of spectra are presented. With the use of the high sensitivity photoacoustic spectrometer, the following values of the absorption coefficient were found: 2.3×10-9cm-1·Pa-1(λ=255 nm), 0.9×10-9 cm-1·Pa-1(λ=271 nm), and 1.6×10-9cm-1 ·Pa-1(λ=289 nm). 相似文献
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ZnO纳米线作为新型太阳能电池结构的重要组成部件之一, 其导电能力直接影响到太阳能电池的性能. 采用密度泛函理论平面波超软赝势方法, 计算并分析了C2H6O(乙醇)、 C6H5FS(4-氟苯硫酚)、 C7HF7S(4-(三氟甲基L)-2, 3, 5, 6-四氟硫代苯酚) 等小分子吸附的六边形结构\langle0001angle ZNWs (ZnO 纳米线) 的几何结构、 吸附能和电子结构. 首先, 通过几何优化得到了不同基团吸附的ZNWs的稳定结构, 同时吸附能计算结果表明C7HF7S吸附的体系结构最为稳定, 且吸附呈现放热反应; 其次, 为研究表面敏化对导电性能的影响, 计算了不同小分子基团吸附下的能带结构和态密度, 并利用能带理论分析了表面吸附敏化对禁带宽度的调控机理, 结果分析表明小分子表面吸附敏化对ZNWs的电学性能有一定的影响, 其中C7H7FS和C6H5FS分子均发生了不同程度的电荷转移. 相似文献
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Jií ejka Silmarilly Bahfenne Ray L. Frost Jií Sejkora 《Journal of Raman spectroscopy : JRS》2010,41(1):74-77
Raman spectra of vajdakite, [(Mo6+O2)2(H2O)2As O5]·H2O, were studied and interpreted in terms of the structure of the mineral. The Raman spectra were compared with the published infrared spectrum of vajdakite. The presence of dimolybdenyl and diarsenite units and of hydrogen bonded water molecules was inferred from the Raman spectra which supported the known and published crystal structure of vajdakite. Mo O and O H···O bond lengths were calculated from the Raman spectra. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Šimon Budzák Philippe Carbonniere Miroslav Medved' Ivan Černušák 《Molecular physics》2014,112(24):3225-3236
Intermolecular interactions in three dimers, CO···H2O, CO···SO2, and CO···NO+, were studied at the CCSD(T) level of theory, using a series of the augmented correlation consistent polarised basis sets. Interaction energy and its components as well as vibrational spectra for local minima were computed using both harmonic and anharmonic approximations. While CO···H2O and CO···SO2 are weakly bound with the binding energies ?7.4 and ?6.4 kJ/mol, CO···NO+ is much more stable with the binding energy of ?32.8 kJ/mol corresponding to ΔG = ?4.7 kJ/mol at 254 K. 相似文献
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Xiao-Jun Sun Wen-Xian Li Wen-Juan Chai Tie Ren Xiao-Yan Shi 《Journal of fluorescence》2010,20(2):453-461
Two novel ternary rare-earth complexes SmL5·L’·(ClO4)2·7H2O and EuL5·L’·(ClO4)2·6H2O (the first ligand L = C6H5COCH2SOCH2COC6H5, the second ligand L’ = C6H4OHCOO−) were synthesized and characterized by element analysis, molar conductivity, coordination titration analysis, IR, TG-DSC,
1HNMR and UV spectra. The detailed luminescence studies on the rare-earth complexes showed that the ternary rare-earth complexes
presented stronger fluorescence intensities, longer lifetimes, and higher fluorescence quantum efficiencies than the binary
rare-earth materials. After the introduction of the second ligand salicylic acid group, the relative emission intensities
and fluorescence lifetimes of the ternary complexes LnL5·L’·(ClO4)2·nH2O (Ln = Sm, Eu; n = 7, 6) enhanced more obviously than the binary complexes LnL5·(ClO4)3·2H2O. This indicated that the presence of both organic ligand bis(benzoylmethyl) sulfoxide and the second ligand salicylic acid
could sensitize fluorescence intensities of rare-earth ions, and the introduction of salicylic acid group was a benefit for
the fluorescence properties of the ternary rare-earth complexes. The fluorescence spectra, fluorescence lifetime and phosphorescence
spectra were also discussed. 相似文献
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Jií ejka Ray L. Frost Jií Sejkora Eloise C. Keeffe 《Journal of Raman spectroscopy : JRS》2009,40(11):1464-1468
Raman spectra of jáchymovite, (UO2)8(SO4)(OH)14·13H2O, were studied, complemented with infrared spectra, and compared with published Raman and infrared spectra of uranopilite, [(UO2)6(SO4)O2(OH)6(H2O)6]·6H2O. Bands related to the stretching and bending vibrations of (UO2)2+, (SO4)2−, (OH)− and water molecules were assigned. U O bond lengths in uranyl and O H· · ·O hydrogen bond lengths were calculated from the Raman and infrared spectra. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Jií ejka Jií Sejkora Silmarilly Bahfenne Sara J. Palmer Jakub Plil Ray L. Frost 《Journal of Raman spectroscopy : JRS》2011,42(2):214-218
Raman spectrum of burgessite, Co2(H2O)4[AsO3OH]2· H2O, was studied, interpreted and compared with its infrared spectrum. The stretching and bending vibrations of (AsO3) and As‐OH units, as well as the stretching, bending and libration modes of water molecules and hydroxyl ions were assigned. The range of O H···O hydrogen bond lengths was inferred from the Raman and infrared spectra of burgessite. The presence of (AsO3OH)2− units in the crystal structure of burgessite was proved, which is in agreement with its recently solved crystal structure. Raman and infrared spectra of erythrite inferred from the RRUFF database are used for comparison. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Jií ejka Jií Sejkora Ray L. Frost Eloise C. Keeffe 《Journal of Raman spectroscopy : JRS》2009,40(12):1786-1790
Raman spectra of metauranospinite Ca[(UO2)(AsO4)]2·8H2O complemented with infrared spectra were studied. Observed bands were assigned to the stretching and bending vibrations of (UO2)2+ and (AsO4)3− units and of water molecules. U O bond lengths in uranyl and O H···O hydrogen bond lengths were calculated from the Raman and infrared spectra. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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L. Graf 《Solid State Communications》1978,27(12):1361-1365
The Raman spectra in FeCl2 · 2H2O (FC2) and the isomorphic compounds FeCl2 · 2D2O (FC2D), MnCl2 · 2H2O (MC2) and CoCl2 · 2H2O (CC2) were observed at 2 K to obtain the frequencies of all 12 optical phonons of even symmetry at the zone center. The lowest of these phonons is known to be coupled resonantly to the magnons below TN. This coupling and other important magnetic properties of the iron salts are determined by the influence of the crystal field. The electronic transitions of the Fe2+-ion in a crystal field are identified after a thorough assignment of the phonon lines in the four isomorphic compounds to symmetry types, using back-scattering and 90°-scattering techniques. 相似文献
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Tianlei Zhang Xinguang Lan Rui Wang Soumendra Roy Zhangyu Qiao Yousong Lu 《Molecular physics》2018,116(14):1783-1794
The addition reaction of CH2OO + H2O → CH2(OH)OOH without and with X (X = H2CO3, CH3COOH and HCOOH) and H2O was studied at CCSD(T)/6-311+ G(3df,2dp)//B3LYP/6-311+G(2d,2p) level of theory. Our results show that X can catalyse CH2OO + H2O → CH2(OH)OOH reaction both by increasing the number of rings, and by adding the size of the ring in which ring enlargement by COOH moiety of X inserting into CH2OO···H2O is favourable one. Water-assisted CH2OO + H2O → CH2(OH)OOH can occur by H2O moiety of (H2O)2 or the whole (H2O)2 forming cyclic structure with CH2OO, where the latter form is more favourable. Because the concentration of H2CO3 is unknown, the influence of CH3COOH, HCOOH and H2O were calculated within 0–30 km altitude of the Earth's atmosphere. The results calculated within 0–5 km altitude show that H2O and HCOOH have obvious effect on enhancing the rate with the enhancement factors are, respectively, 62.47%–77.26% and 0.04%–1.76%. Within 5–30 km altitude, HCOOH has obvious effect on enhancing the title rate with the enhancement factor of 2.69%–98.28%. However, compared with the reaction of CH2OO + HCOOH, the rate of CH2OO···H2O + HCOOH is much slower. 相似文献
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V. Ananthanarayanan 《Zeitschrift für Physik A Hadrons and Nuclei》1961,163(2):144-157
Raman spectra of single crystals of K2M(SO4)2 · 6 H2O where M=Mg, Zn, Ni or Co have been recorded for the first time usingλ 2537 as the exciting radiation. The corresponding five single sulphates have also been studied. Interesting results concerning the substitution of magnesium, zinc, nickel or cobalt in the double sulphate lattice on the sulphate frequencies are observed. The lattice spectra of these double sulphates are analysed group theoretically and discussed in relation to the lattice spectra of the corresponding individual sulphates. Certain new results concerning the Raman spectra of the individual sulphates have also been obtained and in the case of CoSO4 · 7 H2O the spectrum has been recorded for the first time. 相似文献
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Wen-Xian Li Wen-Juan Chai Xiao-Jun Sun Tie Ren Xiao-Yan Shi 《Journal of fluorescence》2010,20(4):873-880
Two novel ternary rare earth complexes of Tb(III) and Dy(III) perchlorates with bis(benzoylmethyl) sulfoxide (L) and benzoic
acid (L′) had been synthesized and characterized by elemental analysis, coordination titration analysis, molar conductivity,
IR, TG-DSC, 1HNMR and UV spectra. The results indicated that the composition of these complexes was REL5L′(ClO4)2·nH2O (RE= Tb(III), Dy(III); L=C6H5COCH2SOCH2COC6H5, L′=C6H5COO; n = 6,8). The fluorescence spectra illustrated that the ternary rare earth complexes presented stronger fluorescence intensities,
longer lifetimes and higher fluorescence quantum efficiencies than the binary rare earth complexes REL5·(ClO4)3·2H2O. After the introduction of the second ligand benzoic acid group, the relative fluorescence emission intensities and fluorescence
lifetimes of the ternary complexes REL5L′(ClO4)2·nH2O (RE= Tb(III), Dy(III)) enhanced more obviously than the binary complexes. This indicated that the presence of both organic
ligands bis(benzoylmethyl) sulfoxide and the second ligand benzoic acid could sensitize fluorescence intensities of rare earth
ions, and the introduction of benzoic acid group was resulted in the enhancement of the fluorescence properties of the ternary
rare earth complexes. The phosphorescence spectra were also discussed. 相似文献