Stokes direct-line fluorescence

Figure 7.57 Example of atomic fluorescence transitions (a) resonance fluorescence, (b) Stokes direct-line fluorescence, and (c) anti-Stokes direct-line fluorescence.

If the wavelength of the fluorescence line is greater than that of the excitation line, the effect is called Stokes direct line fluorescence. In the... 

In a nonresonance fluorescence transition, the photons involved in absorption and fluorescence processes have different wavelengths (Figure IB). The particular transition shown in Figure IB is called Stokes direct-line fluorescence, which is frequently used for AFS with laser excitation. Nonresonance transitions have the advantage that a wavelength selection device can be used to distinguish between fluorescence and scattered source radiation. 

Figure 2. Classification of LEAF schemes A) Resonance fluorescence B) Direct-line fluorescence C) Collisionally assisted direct-line fluorescence D) Anti-Stokes direct-line fluorescence...

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