All substance is made up of elements, and elements are made up of atoms, atom is made up of a nucleus and electrons, each electron are in certain level, have certain energy, under normal state, atoms in the steady state, It has the lowest energy, this kind of state called the ground state。
When the material is subjected to the role of external energy , the extra nuclear electron will transition to high level, in a high energy state electronic is unstable, excited states of atoms can alive for 10-8 seconds, it transition to the ground state from high energy state, or when in A lower energy state, it can Release the excess energy in the form of light, the atomic energy level transition figure.
The Abscissa represents atoms located level; Eo as the ground state energy, generally to be zero, the released energy Δ E and radiation of wavelength λ is as follows.The vertical coordinates of each level with the energy,
Because the ground state of each element is different, the excited state is not the same, so the photons are not consistent; it is also mean the different wavelength.
Based on the wavelength determines element, this is the qualitative analysis of the spectrum. On the other hand, the photon number of the launch of the spectral lines determines the spectral line intensity, more photon number, more strength, or photon number then weak, and the number of photons in the ground state was decided by the atomic number, and the ground state atomic number are decided by the content of an element,。
So according to the intensity of spectral lines can get a certain element content.