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Laser-induced fluorescence (LIF) or laser-stimulated fluorescence (LSF)[1] is a spectroscopic method in which an atom or molecule is excited to a higher energy level by the absorption of laser light followed by spontaneous emission of light.[2][3] It was first reported by Zare and coworkers in 1968.[4][5]

LIF is used for studying structure of molecules, detection of selective species and flow visualization and measurements. The wavelength is often selected to be the one at which the species has its largest cross section. The excited species will after some time, usually in the order of few nanoseconds to microseconds, de-excite and emit light at a wavelength longer than the excitation wavelength. This fluorescent light is typically recorded with a photomultiplier tube (PMT) or filtered photodiodes.

Types

Two different kinds of spectra exist, disperse spectra and excitation spectra.

The disperse spectra are performed with a fixed lasing wavelength, as above and the fluorescence spectrum is analyzed. Excitation scans on the other hand collect fluorescent light at a fixed emission wavelength or range of wavelengths. Instead the lasing wavelength is changed.

An advantage over absorption spectroscopy is that it is possible to get two- and three-dimensional images since fluorescence takes place in all directions (i.e. the fluorescence signal is usually isotropic). The signal-to-noise ratio of the fluorescence signal is very high, providing a good sensitivity to the process. It is also possible to distinguish between more species, since the lasing wavelength can be tuned to a particular excitation of a given species which is not shared by other species.

LIF is useful in the study of the electronic structure of molecules and their interactions. It has also been successfully applied for quantitative measurement of concentrations in fields like combustion, plasma, spray and flow phenomena (such as molecular tagging velocimetry), in some cases visualizing concentrations down to nanomolar levels. LED-induced fluorescence has been used in situ to delineate aromatic hydrocarbon contamination as a cone penetrometer add on module and also as a percussive capable asset.

Applications

Detection of purity[6]
Optical tumor diagnosis
Imaging of paleontological specimens[1]
Detection and quantification of biomolecules and biological processes (e.g. DNA sequencing, trace protein analysis, polymerase chain reaction products, and single-cell analysis)[7][8]
Measurement of ion distribution functions and velocity space diffusion and convection in a plasma[9]

See also

Fluorescence microscope
Planar laser-induced fluorescence
Ultrafast laser spectroscopy

References

Kaye, T.G.; Falk, A.R.; Pittman, M.; Sereno, P.C.; Martin, L.D.; Burnham, D.A.; Gong, E.; Xu, X.; Wang, Y. (2015). "Laser-Stimulated Fluorescence in Paleontology". PLoS ONE. 10 (5): e0125923. doi:10.1371/journal.pone.0125923. PMC 4446324. PMID 26016843.
Kinsey, J L (1977). "Laser-Induced Fluorescence". Annual Review of Physical Chemistry. 28 (1): 349–372. Bibcode:1977ARPC...28..349K. doi:10.1146/annurev.pc.28.100177.002025. ISSN 0066-426X.
Richard W. Solarz; Jeffrey A. Paisner (29 September 1986). Laser Spectroscopy and its Applications. CRC Press. pp. 623–. ISBN 978-0-8247-7525-4.
Tango, William J. (1968). "Spectroscopy of K2 Using Laser-Induced Fluorescence". The Journal of Chemical Physics. 49 (10): 4264–4268. Bibcode:1968JChPh..49.4264T. doi:10.1063/1.1669869. ISSN 0021-9606.
Zare, R. N. (2012). "My Life with LIF: A Personal Account of Developing Laser-Induced Fluorescence". Annual Review of Analytical Chemistry. 5: 1–14. Bibcode:2012ARAC....5....1Z. doi:10.1146/annurev-anchem-062011-143148. PMID 22149473.
Takeyuki, Tanaka; et al. "The Application of Laser Induced Fluorescence Spectroscopy to Measurement of Purity Level in Textiles". Jido Seigyo Rengo Koenkai. Archived from the original on 13 February 2011. Retrieved 11 October 2008.
Lin, Yang-Wei; Chiu, Tai-Chia; Chang, Huan-Tsung (2003). "Laser-induced fluorescence technique for DNA and proteins separated by capillary electrophoresis". Journal of Chromatography B. 793 (1): 37–48. doi:10.1016/s1570-0232(03)00363-5. ISSN 1570-0232. PMID 12880853.
Zare, Richard N. (2012-07-19). "My Life with LIF: A Personal Account of Developing Laser-Induced Fluorescence". Annual Review of Analytical Chemistry. 5 (1): 1–14. Bibcode:2012ARAC....5....1Z. doi:10.1146/annurev-anchem-062011-143148. ISSN 1936-1327. PMID 22149473.
Skiff, Fred; Bollinger, John (23 April 2004). "Mini-conference on laser-induced fluorescence in plasmas". Physics of Plasmas. 11 (5): 2972. doi:10.1063/1.1668287.

Lasers

List of laser articles List of laser types List of laser applications Laser acronyms

Laser types: Solid-state
Semiconductor Dye Gas
Chemical Excimer Ion Metal Vapor

Laser physics

Active laser medium Amplified spontaneous emission Continuous wave Doppler cooling Laser ablation Laser cooling Laser linewidth Lasing threshold Magneto-optical trap Optical tweezers Population inversion Resolved sideband cooling Ultrashort pulse

Laser optics

Beam expander Beam homogenizer B Integral Chirped pulse amplification Gain-switching Gaussian beam Injection seeder Laser beam profiler M squared Mode-locking Multiple-prism grating laser oscillator Multiphoton intrapulse interference phase scan Optical amplifier Optical cavity Optical isolator Output coupler Q-switching Regenerative amplification

Laser spectroscopy

Cavity ring-down spectroscopy Confocal laser scanning microscopy Laser-based angle-resolved photoemission spectroscopy Laser diffraction analysis Laser-induced breakdown spectroscopy Laser-induced fluorescence Noise-immune cavity-enhanced optical heterodyne molecular spectroscopy Raman spectroscopy Second-harmonic imaging microscopy Terahertz time-domain spectroscopy Tunable diode laser absorption spectroscopy Two-photon excitation microscopy Ultrafast laser spectroscopy

Laser ionization

Above-threshold ionization Atmospheric-pressure laser ionization Matrix-assisted laser desorption/ionization Resonance-enhanced multiphoton ionization Soft laser desorption Surface-assisted laser desorption/ionization Surface-enhanced laser desorption/ionization

Laser fabrication

Laser beam welding Laser bonding Laser converting Laser cutting Laser cutting bridge Laser drilling Laser engraving Laser-hybrid welding Laser peening Multiphoton lithography Pulsed laser deposition Selective laser melting Selective laser sintering

Laser medicine

Computed tomography laser mammography Laser capture microdissection Laser hair removal Laser lithotripsy Laser coagulation Laser surgery Laser thermal keratoplasty LASIK Low-level laser therapy Optical coherence tomography Photorefractive keratectomy Photorejuvenation

Laser fusion

Argus laser Cyclops laser GEKKO XII HiPER ISKRA lasers Janus laser Laboratory for Laser Energetics Laser integration line Laser Mégajoule Long path laser LULI2000 Mercury laser National Ignition Facility Nike laser Nova (laser) Novette laser Shiva laser Trident laser Vulcan laser

Civil applications

3D laser scanner CD DVD Blu-ray Laser lighting display Laser pointer Laser printer Laser tag

Military applications

Advanced Tactical Laser Boeing Laser Avenger Dazzler (weapon) Electrolaser Laser designator Laser guidance Laser-guided bomb Laser guns Laser rangefinder Laser warning receiver Laser weapon LLM01 Multiple Integrated Laser Engagement System Tactical High Energy Laser Tactical light ZEUS-HLONS (HMMWV Laser Ordnance Neutralization System)

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