Atomic energy level refers to the energy of atomic systemquantizationVisual representation of.according toquantum mechanicsTheory, cancalculationThe energy of the atomic system is quantized, and the energy takes a series of discrete values;The energy value depends on a certainQuantum numberTherefore, the energy level is marked with a certain quantum number.
Chinese name
Atomic energy level
Foreign name
atomic energy levels
Description
Atomic system energyquantizationVisual representation of
The energy level depends on the atomicElectronic configurationIn addition, it also depends on the coupling type of intra atomic interaction. In the LS coupling case, the total orbitangular momentum, total spin and total angular momentumQuantum number50. S and J are good quantum numbers, and energy levels are marked with certain symbols.For example, the symbol of a certain energy level of helium atom is 1s2p3p2, where the left part 1s2p is the electronic configuration, and the upper left corner of the Latin letters S, P, D, F... whose capital Latin letters correspond to L=0, 1, 2, 3,... respectively is 2S+1, representing the multiple stateMultiplicityThe value in the lower right corner is J value.In a magnetic fieldAtomic magnetic momentThe interaction with the magnetic field leads to energy level splitting, and the correspondingMagnetic quantum numberMark them separately.
structure
Announce
edit
Fine structure of energy levels of bivalent atoms under atypical coupling
Fine structure diagram of configuration energy level
Under the typical coupling (LS and jj coupling), the fine structure problem of the energy levels of bivalent atoms has been solved.However, in general, LS coupling is only applicable to the case where the magnetic interaction between electrons and nuclei is far less than the electrostatic interaction between electrons (non central force part);Jj coupling is only applicable to the case where the magnetic interaction between electrons and nuclei is far greater than the electrostatic interaction between electrons (non central force part).Unfortunately, the fine structure energy levels of many divalent atoms are neither attributed to LS coupling nor to jj coupling.This problem has long been found in experiments and many experimental data have been summarized.There are also some theoretical studies, but most of them are limited to some specific atoms or some specific electronic configurations, and no complete theoretical system has been given.The related research attempts to give a general theory for calculating the fine structure energy levels of bivalent atoms under the atypical coupling based on the typical coupling theory, and the results under the typical coupling will be taken as a special case of the atypical coupling.
On the basis of typical coupling theory, the calculation of fine structure of bivalent atoms under atypical coupling is givenenergy levelThe results are consistent with the experimental data, and intuitively show that typical coupling is only a special case of atypical coupling.[1]
influence
Announce
edit
Influence of Plasma Shielding Effect on Atomic Energy Levels
Research progress
Driven by experimental technology, GaoionizationThe experimental observation and theoretical study of high charged ions in the ion exchange region have aroused people's interest again, and people have carried out a lot of work in this area.Among them, a very important work is to accurately determine the element in thePlasmaEnergy level structure and oscillator strength in the environment.These atomic data are available inPlasma diagnosticsas well asPlasma radiationOpacity research plays an important role. For example, Brage et al. pointed out that the ratio of oscillator strengths of two transitions with the same initial state and similar final state energies can be used to diagnose the local electron density in plasma;Rubiano et al. used the hydrogen shielding model to calculate atomic data such as radiative transitions of aluminum, and then used it to calculate the radiative opacity of aluminum;Saha et al. also mentioned that the spectral line intensity of Be like elements can be used to diagnose the temperature and density of plasma.
The actual plasma contains a large amount offree electronAnd ions of various valence states. To accurately calculate the plasmaShielding effectIt is difficult to influence the energy level structure and oscillator strength.The usual method is to average the effect of the plasma environment to get a relatively simple expression, which greatly simplifies the calculation process.The following two models are usually used to calculate the characteristics of each valence ion in the plasma environment: the first is to use the self consistent field model that takes into account the temperature effect and density effect to calculate the potential function.However, this self consistent field, which takes into account the plasma shielding effect, needs to be solved by cyclic iteration. If a large amount of atomic data needs to be calculated, the calculation time will be very long.The second method is to find the analytical expression of the potential function taking into account the plasma shielding effect,Debye modelIt is one of them.Its basic idea is to assume that the electric field potential considering the plasma shielding effect is determined by the spherically symmetric charge distribution, and that the kinetic energy of particles is far greater than the potential energy between particles, and the distribution of particles in the plasma meets Boltzmann statistics, so that the Debye shielding potential can be obtained from the spherically symmetric Poisson equation under the first order approximation of Debve.Since Debye et al put forward the Debye model in 1923, it has been widely used in the field of atoms and molecules.The Debve model can not only be used to calculate various cross sections, spectral line shifts and linetypes of hydrogen like ions, but also be used to study multi electron systems.Especially in recent decades, people have done a lot of work using the Debve model to study the influence of plasma shielding effect on the atomic structure of hydrogen like, helium like, multi electron system elements.Rubiano et al., Bielinska Waz et al., Rodrfguez et al., Saha et al. considered the influence of relativistic effects on atomic radiation characteristics.However, there are few studies on the atomic structure of Z element in Be like plasma.
Relevant research uses plasmaShielding effectAll ofrelativityMCDF (multi configuration Dirac Work) model of
The advanced GRASP2 program calculates the energy level structure and oscillator strength of 11 Be like ions such as MnXXII-BrXXXII, and focuses on the 2s of the lowest two configurationstwoOne [2s1/2，2p1/2]oneAnd 2stwoOne [2s1/2，2p3/2]oneTheir energy levels and oscillator strengths under different plasma shielding conditions are given.These two spectral lines, which are extremely important for plasma diagnosis, have been observed in astrophysics and laboratories.
theoretical model
For complex atoms,Configuration interaction(configure interaction, CI) plays a very important role in atomic structure calculation, but in actual calculation, it is impossible to include all possible configuration interactions, and configuration is usually selected by controlling the number of electronic excitations.When considering the configuration interaction, only the configuration formed by the excitation of at most two electrons to the high energy orbit is included. When solving the wave function by CI method, if the error before and after the energy level is less than 10 in the process of gradually increasing the configuration-5The CI is considered to have met the accuracy requirements, and no configuration will be added.
In fact, the Debye model does not need high temperature conditions. As long as the r value is large enough, the temperature does not need to be too high, and the system also meets the Debye approximation.However, when the plasma environment does not meet the Debve approximation, the plasmaShielding effectWe need to introduce other models, such as the ion sphere model.Fortunately, the averageHigh temperature plasmaAll meet this condition.In the above derivation, only the static shielding effect is introduced, while the dynamic shielding effect is ignored.If we want to calculate the influence of plasma shielding effect on atomic structure more accurately, we need to take all the above factors into account.
conclusion
The influence of plasma shielding effect on the atomic structure, transition energy levels and oscillator strength of Be like ions is studied by using the MCDF model.The 2s of the lowest two configurations of 11 Be like ions such as MnXXII-BrXXXII are calculatedtwoOne [2s1/2，2p1/2]oneAnd 2stwoOne [2s1/2，2p3/2]oneThe transition of.The calculation results show that after considering the plasma shielding effect, the spectral lines and their corresponding oscillator strengths will appearblue shiftIt can be seen that the blue shift phenomenon is very sensitive to the plasma shielding effect. At a certain temperature, with the increase of electron density, the blue shift will rapidly increase in an exponential form.For the middle Z element, the blue shift of the spectral line mainly comes from the shielding effect of the external environment on the interaction between the nucleus and the electron, while the shielding effect of the external environment on the interaction between the electrons is relatively weak.
Debye model has its scope of application. It can only be used in the case of weak particle couplingPlasmaFor example, high temperature and low density plasma.In addition, it also requiresDebye radiusLarge enough to contain enoughfree electron。In the above calculation, only the static shielding effect is considered, but not the dynamic shielding effect. If you want to further study the influence of plasma shielding effect, it is necessary to consider the influence of this factor.[2]
