Laser-induced fluorescence

Laser-induced fluorescence (engl. Laser-induced fluorescence , LIF) is a spectroscopic measuring method. It is based on fluorescence excitation by a laser and therefore belongs to the group of laser spectroscopy .

description

If an atom, molecule or substance is illuminated with a laser beam whose light has a frequency from the absorption range of the substance, the laser excitation results in fluorescence. The intensity of the fluorescence depends on the absorption spectrum of the substance and the intensity of the laser beam. Above a critical intensity, saturation effects or even (reversible or irreversible) destruction of the excited substance can occur. A radiationless de-excitation of the material is called quenching .

In technology, LIF methods are u. a. used to determine substance concentrations in gases and liquids. In combustion technology in particular, laser-induced fluorescence is used to detect the OH radical (OH concentration) and nitrogen oxides.

In physics, time-resolved LIF techniques are used, for example, to determine the lifetime of excited atomic or molecular states.

In bioanalysis, the LIF is used in laser scanning microscopy (LSM).

Individual evidence

^ Manfred Hugenschmidt: Lasermesstechnik: Diagnostik der Kurzzeitphysik . Springer, Berlin, Heidelberg, New York 2007, ISBN 978-3-540-29920-2 , pp. 320-322 .
^ Friedrich Lottspeich, Joachim W. Engels (Ed.): Bioanalytik . 3. Edition. Springer Spectrum, Berlin, Heidelberg 2012, ISBN 978-3-8274-2942-1 , Chapter 9: Light microscopic methods - Imaging .

[hugenschmidt-1] Manfred Hugenschmidt: Lasermesstechnik: Diagnostik der Kurzzeitphysik . Springer, Berlin, Heidelberg, New York 2007, ISBN 978-3-540-29920-2 , pp. 320-322 .

[lottspeich-2] Friedrich Lottspeich, Joachim W. Engels (Ed.): Bioanalytik . 3. Edition. Springer Spectrum, Berlin, Heidelberg 2012, ISBN 978-3-8274-2942-1 , Chapter 9: Light microscopic methods - Imaging .