Oscillator Strength

An atom or a molecule can absorb light and undergo a transition from one quantum state to another. The oscillator strength is a dimensionless quantity to express the strength of the transition. The oscillator strength of a transition from a lower state to an upper state may be defined by

f_{12} = \frac{2 }{3}\frac{m_e}{\hbar^2}(E_2 - E_1) \sum_{m_2} \sum_{\alpha=x,y,z} | \langle 1 m_1 | R_\alpha | 2 m_2 \rangle |^2,

where is the mass of an electron and is the reduced Planck constant. The quantum states 1,2,..., are assumed to have several degenerate sub-states, which are labeled by . "Degenerate" means that they all have the same energy . The operator is the sum of the x-coordinates of all electrons in the system, etc.:

R_\alpha = \sum_{i=1}^N r_{i,\alpha}.

The oscillator strength is the same for each sub-state .

Read more about Oscillator Strength:  Thomas–Reiche–Kuhn Sum Rule, See Also

Famous quotes containing the word strength:

    “My topic for Army reunions ... this summer: How to prepare for war in time of peace. Not by fortifications, by navies, or by standing armies. But by policies which will add to the happiness and the comfort of all our people and which will tend to the distribution of intelligence [and] wealth equally among all. Our strength is a contented and intelligent community.”
    —Rutherford Birchard Hayes (1822–1893)