|
In atomic physics, the fine structure describes the splitting of the spectral lines of atoms due to electron spin and relativistic corrections to the non-relativistic Schrödinger equation. The gross structure of line spectra is the line spectra predicted by the quantum mechanics of non-relativistic electrons with no spin. For a hydrogenic atom, the gross structure energy levels only depend on the principal quantum number n. However, a more accurate model takes into account relativistic and spin effects, which break the degeneracy of the energy levels and split the spectral lines. The scale of the fine structure splitting relative to the gross structure energies is on the order of (''Zα'')2, where ''Z'' is the atomic number and ''α'' is the fine-structure constant, a dimensionless number equal to approximately . The fine structure can be separated into three corrective terms: the kinetic energy term, the spin-orbit term, and the Darwinian term. The full Hamiltonian is given by : This can be seen as a non-relativistic approximation of the Dirac equation. ==Kinetic energy relativistic correction== Classically, the kinetic energy term of the Hamiltonian is : where is the momentum and is the mass of the electron. However, when considering a more accurate theory of nature viz. perturbation, we can calculate the first order energy corrections due to relativistic effects. : where is the unperturbed wave function. Recalling the unperturbed Hamiltonian, we see : We can use this result to further calculate the relativistic correction: : &= -\frac\left\langle\psi^0\right\vert (2m)^2 (E_n - V)^2\left\vert\psi^0\right\rangle \\ E_n^ &= -\frac\left(E_n^2 - 2E_n\langle V\rangle + \left\langle V^2\right\rangle \right) \end For the hydrogen atom, , , and where is the Bohr Radius, is the principal quantum number and is the azimuthal quantum number. Therefore the first order relativistic correction for the hydrogen atom is : where we have used: : On final calculation, the order of magnitude for the relativistic correction to the ground state is . 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Fine structure」の詳細全文を読む スポンサード リンク
|