【作者】 赵玉杰；

【导师】 盛六四； 刘付轶；

【作者基本信息】 中国科学技术大学 ， 同步辐射及应用， 2009， 博士

【摘要】 本论文主要介绍了利用同步辐射真空紫外光电离和光吸收谱,结合量子化学计算,从实验和理论上研究小分子的单电离和双电离,同时还介绍了国家同步辐射实验室原子分子物理光束线气体滤波器的研制、安装和调试工作。第1章主要介绍了原子分子领域的光电离和光吸收研究概况,并给出了绝热电离能、垂直电离能、超激发态、光电离界面、原子分子的里德堡态、离解与预离解的概念。随后介绍了双电离和离解的研究概况。然后也对实验研究方法如光电离质谱、荧光光谱、光吸收谱、光电子谱和符合技术进行了介绍。最后简单介绍了量化计算的方法和理论。第2章主要介绍了国家同步辐射实验室原子分子实验线站光电离和光吸收实验使用的装置和技术。首先概述了同步辐射光源的特点及应用。随后介绍了原子分子光束线的光学元件和性能参数,光束线由插入件波荡器提供高亮度的真空紫外波段（7.5-124 eV）辐射。最后概述了原子分子实验站使用的装置和技术,介绍了超声分子束技术、反射式飞行时间质谱仪以及多级光电离吸收室的原理和技术。第3章由于原子分子光束线由波荡器提供真空紫外辐射,由此带来了高次谐波问题,为了提高原子分子光电离和光吸收数据的可靠性,从而更精确研究分子光谱结构。我们采用了气体滤波器装置来抑制高次谐波的干扰。因此我们在第三章介绍了气体滤波器的研制、安装和调试。为了有效消除波荡器产生的高次谐波的影响,同时维持光束线及储存环超高真空环境,并根据原子分子物理光束线实际情况,我们采用了二级差分抽气系统及大抽速的差分泵来设计气体滤波器系统。调试结果表明气体滤波器的研制达到了预期目标,满足了实验要求。第4章利用同步辐射和多级电离吸收室技术,在真空紫外波段630～900（?）测量了CO的VUV光吸收谱,得到CO分子的电离阈值。根据光吸收谱,结合量子亏损理论计算,对其光吸收谱的电子态振动跃迁Rydberg系列进行了指认。与以前的研究结果相比较,我们的光谱分辨更高,可清楚的地分辨出CO分子的光谱结构,结构信息更丰富和精确。不仅扩充了原有Rydberg系列和振动序列,而且探索性地指认了新的序列。这些光谱数据可为大气层和天体物理等研究提供参考数据。第5章利用同步辐射真空紫外光电离技术,结合超声分子束和反射式飞行质谱仪,研究了14-41 eV能量范围内CO的光电离和离解过程,结合理论计算,详细讨论了CO的预离解和离解过程,并指认了解离过程中一些离子态和动力学过程。第6章利用同步辐射真空紫外光电离质谱和光电离效率谱,获得了一些小分子的双电离能,同时我们利用Gaussian-03程序的G2方法计算了这些小分子的绝热双电离能。总的来说我们实验测得的双电离能与理论计算获得的绝热双电离能比较吻合。通过比较实验和理论计算的结果,我们讨论这些小分子双电离的机制。通过与文献比较,对这些分子发生双电离前后键长、键角和振动频率的变化也做了讨论。第7章介绍了实验中首次探测到氟利昂（F-22）的母体二价离子CHF₂Cl_<sup>2+和其主要碎片二价离子(CHCl²⁺,CF₂²⁺和CHFCl²⁺)。利用同步辐射真空紫外光电离质谱和光电离效率谱,获得了氟利昂（F-22）的双电离能和主要碎片二价离子的出现势。同时在Gaussian-03程序上利用密度泛函的方法计算了氟利昂（F-22）的垂直双电离能的理论值。通过比较实验和理论以及经验公式计算的结果,讨论了氟利昂（F-22）双电离的机理。同时还讨论产生主要碎片二价离子的离解通道和离解能。这些数据将为以后氟利昂（F-22）大气光化学研究提供重要的信息。更多还原

【Abstract】 The dissertation mainly introduces the experimental and theoretical studies on single and double photonization of small molecules by using tunable VUV synchrotron radiation.It also introduces the development,installation and adjustment of gas filter system of atomic and molecular physics beamline at National Synchrotron Radiation Laboratory.In the first chapter,it introduces the present status of investigation on photoionization and photoabsorption of atoms and molecules.The basic conceptions of photoionization and photodissociation,such as adiabatic ionization energy,vertical ionization energy,superexcited states,Rydberg states,photoionization cross section, photoabsorption cross section,photodissociation,predissociation,and so on,are discussed in details.Then,the common experimental method,including photoionization mass spectrometry,photoabsorption spectrometry,fluorescence spectrum,photoelectron spectrum,threshold photoelectron spectrum and some coincidence technologies,are also introduced.Finally,the theoretical calculation methods are also described in detail,In the second chapter,first,it summarizes the development,characteristics and applications of synchrotron radiation.Secondly,it introduces the structure and equipments of atomic and molecular physics beamline and endstation at National Synchrotron Radiation Laboratory.The undulator can provide the tunable VUV synchrotron radiation in the energy range of 7.5-124 eV.Finally,the formation mechanism of ultrasonic molecular beam,principle of time of flight mass spectrometer and multi-photonization photoabsorption chamber are discussed in details.In the third chapter,a differentially pumped rare gas cell has been developed to suppress high order harmonics on the atomic and molecule physics beamline at National Synchrotron Radiation Laboratory.The gas filter system contains a gas absorption cell and two differential pumping systems in consideration of the present status of atomic and molecule physics beamline.The adjustment results indicats that when the pressure of Ar in the gas absorption cell is set to 9.31 Torr,the filter factor of gas filter system is better than 99.975%.Generally speaking,the adjustment results of the gas filter system are in agreement with the design parameters and can meet the experimental requirement very well.In the fourth chapter,Photoabsorption spectra of CO are investigated in energy region 630-900（?） by using synchrotron radiation.Rydberg series converging to the X²∑,A²∏and B²∑states of CO⁺ are identified,and the quantum detect values are also calculated.By analysis and comparison,our results are accurate and credible.Besides Rydberg series and vibrational progressions are extended,some new Rydberg series are also identified clearly.In the fifth chapter,the ionization energy of CO and appearance energies for its fragment ions（C⁺,O⁺）,are determined with photoionization efficiency spectroscopy. The total energies of CO molecule and all fragment products are calculated using Gaussian 03 program and Gaussian 2 calculations.And then,the adiabatic double ionization energy of CO molecule,appearance potentials for its fragment ions and dissociation energies to produce them are predicated by using high accuracy energy mode.The experimental ionization energy and appearance potentials are all in reasonable agreement with their respective calculated energies.The states of fragments are identified in the dissociative course.The mechanisms of photoionization,predissociation and photodissociation of CO are discussed based on comparison of our experimental results with those predicted theoretically.In the sixth chapter,VUV double photoionizations of small molecules（NO,CO, CO₂,CS₂,OSC and NH₃） are investigated with photoionization mass spectroscopy using synchrotron radiation.The double ionization energies of molecules are determined with photoionization efficiency spectroscopy.The total energies of these molecules and their parent dications(NO²⁺,CO²⁺,CO₂²⁺,CS₂²⁺,OSC²⁺ and NH₃²⁺) are calculated using Gaussian 03 program and Gaussian 2 calculations.And then,the adiabatic double ionization energies of molecules are predicated by using high accuracy energy mode.The experimental double ionization energies of these small molecules are all in reasonable agreement with their respective calculated adiabatic double ionization energies.The mechanisms of double photoionization of these molecules are discussed based on comparison of our experimental results with those predicted theoretically.The equilibrium geometries and harmonic vibrational frequencies of molecules and their parent dications are calculated by using MP2（full） method.The differences of configurations between these molecules and their parent dications are also discussed on the basis of theoretical calculations.In the seventh chapter,VUV double photoionization of CHF₂Cl in an energy region 32-40 eV is investigated with photoionization mass spectroscopy by using synchrotron radiation.The double ionization energy of CHF₂Cl and appearance energies for its main fragment dications(CHCl²⁺,CF₂²⁺ and CHFCl²⁺),are determined with photoionization efficiency spectroscopy for the first time.The single point energies of CHF₂Cl and its parent dication(CHF₂Cl²⁺) are calculated using Gaussian 03 program and density functional theory（DFT,B3LYP functional）.The vertical double ionization energy of CHF₂Cl is predicted by using B3LYP method and empirical equation.According to our research results,the experimental double ionization energy of CHF₂Cl is in good agreement with the theoretically calculated vertical double ionization energy.The mechanism of double photoionization of CHF₂Cl is discussed based on the comparison of our experimental results with those predicted theoretically.更多还原