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Topic: Fluorescence spectroscopy


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In the News (Mon 24 Jun 19)

  
  Center for Fluorescence Spetroscopy
For the past 15 years the CFS by the P41 mechanism, has advanced the technology for fluorescence and its applications to the biosciences.
Considerable progress has been made in the CFS and elsewhere in areas such as probe chemistry, multi-photon excitation, steady state imaging, time-resolved imaging, genetically engineered probes, and single molecule detection.
The role of the CFS has typically been to develop the fundamental chemistry, instruments or analysis methods which are then applied to areas such as fluorescence sensing, genetic analysis and cellular imaging.
cfs.umbi.umd.edu   (171 words)

  
  Fluorescence spectroscopy - Wikipedia, the free encyclopedia
Fluorescence spectroscopy or fluorometry is a type of electromagnetic spectroscopy used for analyzing fluorescent spectra.
Fluorescence spectroscopy is primarily concerned with electronic states and vibrational states.
In fluorescence spectroscopy, the species is first excited, by absorbing a photon of light, from its ground electronic state to one of the various vibrational states in the excited electronic state.
en.wikipedia.org /wiki/Fluorescence_spectroscopy   (411 words)

  
 Spectroscopy - Wikipedia, the free encyclopedia
Spectroscopy is the study of spectra, that is, the dependence of physical quantities on frequency.
Spectroscopy is often used in physical and analytical chemistry for the identification of substances, through the spectrum emitted or absorbed.
Raman spectroscopy uses the inelastic scattering of light to analyse vibrational and rotational modes of molecules.
en.wikipedia.org /wiki/Spectroscopy   (1620 words)

  
 Tom Obsil's Page - Fluorescence Spectroscopy
In absorbance spectroscopy the PMT must be able to detect a slight difference in the number of photons which pass through the sample and reference cell.
It is experimentally observed that quenchers reduce the fluorescent intensity in a manner proportional to the concentration of the quencher.
The ratio of the fluorescence intensities in the absence and presence of the quencher are:
members.tripod.com /obsil/fluor.html   (3220 words)

  
 Invitrogen - Molecular Probes - Introduction to Fluorescence Techniques
Under the same conditions, the fluorescence emission spectrum is independent of the excitation wavelength, due to the partial dissipation of excitation energy during the excited-state lifetime, as illustrated in Figure 1.
Fluorescence intensity is quantitatively dependent on the same parameters as absorbance — defined by the Beer–Lambert law as the product of the molar extinction coefficient, optical path length and solute concentration —; as well as on the fluorescence quantum yield of the dye and the excitation source intensity and fluorescence collection efficiency of the instrument.
Fluorescence detection sensitivity is severely compromised by background signals, which may originate from endogenous sample constituents (referred to as autofluorescence) or from unbound or nonspecifically bound probes (referred to as reagent background).
www.probes.com /handbook/sections/0001.html   (4128 words)

  
 Fluorescence spectroscopy of turbid media: Autofluorescence of   (Site not responding. Last check: )
The geometry dependence of 476 nm excited fluorescence of the human arterial wall was investigated both experimentally and with a Monte Carlo simulation.
Attenuation of fluorescence by wavelength dependent scattering and reabsorption causes the fluorescence spectra observed at the tissue surface to change with distance from the excitation beam.
The ratio of 600 nm fluorescence to 580 nm fluorescence increases significantly beyond the excitation beam.
omlc.ogi.edu /pubs/abs/keijzer89a.html   (163 words)

  
 Photochemistry and Photobiology: Fluorescence Lifetime Spectroscopy of Glioblastoma Multiforme¶   (Site not responding. Last check: )
Fluorescence spectroscopy of the endogenous emission of brain tumors has been researched as a potentially important method for the intraoperative localization of brain tumor margins.
We investigated the use of time-resolved, laser-induced fluorescence spectroscopy for demarcation of primary brain tumors by studying the time-resolved spectra of gliomas.
Fluorescence spectroscopy of tissues offers a potential method for intraoperative localization of tumor margins, diagnosis of neoplasms and optimization of biopsy and therapeutic procedures (4-6).
www.findarticles.com /p/articles/mi_qa3931/is_200407/ai_n9458792   (1198 words)

  
 Fluorescence
Polarization of fluorescence of phenol in propylene glycol at -70°C shows that the transition moments of the corresponding absorption bands are mutually perpendicular.
The fluorescence of tyrosine is overlapped by the absorption of tryptophan.
Fluorescence depolarization studies of an antibody to which a fluorescent hapten was bound provided evidence for internal flexibility in the immunoglobulin molecule.
rutgers-newark.rutgers.edu /chemistry/grad/chem585/lecture2.html   (1445 words)

  
 Biophysical Journal: standard deviation in fluorescence correlation spectroscopy, The
Fluorescence correlation spectroscopy (FCS) is a versatile technique for in vivo and in vitro investigations of biomolecular interactions.
Fluorescence correlation spectroscopy as a probe of molecular dynamics.
Fluorescence correlation spectrometry of the interaction kinetics of tetramethylrhodamin a-bungarotoxin with Torpedo califonica acetylchoine receptor.
www.findarticles.com /p/articles/mi_qa3938/is_200106/ai_n8975070   (998 words)

  
 CHP - Molecular Fluorescence Spectroscopy   (Site not responding. Last check: )
Molecular fluorescence is the optical emission from molecules that have been excited to higher energy levels by absorption of electromagnetic radiation.
The main advantage of fluorescence detection compared to absorption measurements is the greater sensitivity achievable because the fluorescence signal has in principle a zero background.
The fluorescence is dispersed by another monochromator and detected by a photomultiplier tube.
www.chem.vt.edu /chem-ed/spec/molec/mol-fluo.html   (200 words)

  
 In vivo fluorescence spectroscopy and imaging of human skin   (Site not responding. Last check: )
In vivo fluorescence measurements were performed on healthy human volunteers, and patients with different types of benign and malignant skin tumours.
Fluorescence images, excited with 375 nm and taken with an image intensified CCD camera, on eight malignant melanomas and eight benign lesions did not indicate any fluorescence intensity distribution specific to the malignancy of the lesion.
Neither the shape of the fluorescence spectra, nor the spatial distribution of the fluorescence intensity showed any signature specific to the histopathological nature of the lesions investigated.
omlc.ogi.edu /pubs/abs/sterenborg94.html   (269 words)

  
 Biophysical Journal: Fluorescence lifetime spectroscopy in multiply scattering media with dyes exhibiting ...
ABSTRACT To investigate fluorescence lifetime spectroscopy in tissue-like scattering, measurements of phase modulation as a function of modulation frequency were made using two fluorescent dyes exhibiting single exponential decay kinetics in a 2% intralipid solution.
Fluorescence lifetime spectroscopy is especially advantageous for quantitative biomedical spectroscopy of analytes since the measurement of fluorescence decay kinetics (rather than the fluorescence intensity) eliminates the necessity for the knowledge of the analyte-sensing fluorophore concentration.
Upon combining the fluorescence decay models with the diffusion equation describing light propagation, we seek to describe the propagation and generation of emission light from analyte-sensing fluorophores for quantitative spectroscopy on the basis of first principles.
www.findarticles.com /p/articles/mi_qa3938/is_200208/ai_n9112132   (1182 words)

  
 Learn more about Spectroscopy in the online encyclopedia.   (Site not responding. Last check: )
The recording and studying of spectrum of energy levels in atoms or molecules in the physical sciences is called spectroscopy.
Mossbauer spectroscopy - Measures the absorption of gamma-rays by atoms bound in a solid as a function of gamma-ray energy.
Raman spectroscopy The study of spectra caused by the scattering and change in frequency of light due to the transition between vibrational/rotational energy levels in molecules.
www.onlineencyclopedia.org /s/sp/spectroscopy.html   (381 words)

  
 Fluorescence Research Grows on All Fronts - R & D
Fluorescence spectroscopy remains a powerful analytical technique for the detection and characterization of organic and inorganic compounds.
Indeed, this versatility has allowed fluorescence spectroscopy to be employed in recent years in studies as diverse as identifying possible bacteria contamination on eggs to resolving the dynamics of human protein-protein interactions.
Currently, the VCU lab is "adapting bio-inspired fluorescence by creating synthetic forms of proteins found in fluorescent organisms," says John Anderson, director of the facility.
www.rdmag.com /ShowPR.aspx?PUBCODE=014&ACCT=1400000100&ISSUE=0503&RELTYPE=PR&ORIGRELTYPE=FE&PRODCODE=00000000&PRODLETT=Z   (1014 words)

  
 Invitrogen - Molecular Probes - Note 1.4 - Technical Focus: Fluorescence Correlation Spectroscopy (FCS)
Fluorescence intensity fluctuations measured by FCS represent changes in either the number or the fluorescence quantum yield of molecules resident in the detection volume (Figure 1).
Free fluorescent ligands move in and out of the detection volume (open circle) and are detected as a series of short, randomized fluorescence bursts (left panel).
In a typical FCS measurement, fluorescence intensity is recorded for a small number of molecules in the detection volume (e.g., 3 molecules/femtoliter, equivalent to ~5 nM macroscopic concentration) over a time range from about 1 microsecond to 1 second.
probes.invitrogen.com /handbook/boxes/1571.html   (823 words)

  
 Fluorescence spectroscopy proves capable of detecting inflammatory cells in blood vessels
An experimental time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) device developed by researchers at Cedars-Sinai Medical Center was used to detect the presence of inflammatory cells in the aortas of animals, with results compared to those from pathology studies.
"While previous studies have reported that fluorescence spectroscopy could identify atherosclerotic plaques, we believe this is the first to demonstrate that a fluorescence-based technique is also sensitive to differences in macrophage content versus collagen content.
Laser-induced fluorescence spectroscopy is based on the fact that when molecules in cells are stimulated by light, they respond by becoming excited and re-emitting light of varying colors.
www.eurekalert.org /pub_releases/2005-08/cmc-fsp081105.php   (727 words)

  
 Simulation of Fluorescence Spectroscopy   (Site not responding. Last check: )
Fluorescence intensity (in arbitrary units) and the absorbance of the solution at the excitation wavelength are displayed in the fl boxes.
Instructor's Notes: This is a simulation of room temperature prompt fluorescence of two non-interacting fluorophors in aqueous solution with right angle geometry in a standard cuvette, measured with a corrected dispersive spectrofluorometer.
The simulation displays excitation spectra, emission spectra, and synchronous spectra, relative fluorescence intensity, and absorbance at the excitation wavelength.
www.inform.umd.edu /EdRes/Topic/Chemistry/ChemConference/Software/Spreadsheets/WWW/Fluorescence.html   (1039 words)

  
 Optical filters from Iridian: catalog of thin film optical filters - bandpass, CWDM, dichroic, edge pass, emission, ...
In fluorescence analyses, it is essential that the light source be segregated from the emitted spectrum from the fluorophore so as not to interfere with the analyses.
Fluorescence analysis of bio-medical samples involves the use of light at a particular wavelength to excite a molecule to a higher level of vibrational energy.
The light source used in fluorescence spectroscopy, the fluorophore and the detector all serve to determine spectrally which filter set to use.
www.iridian.ca /products   (595 words)

  
 Alphas and Taus of Tryptophan Fluorescence in Membranes -- Ladokhin and White 81 (3): 1825 -- Biophysical Journal
Fluorescence measurements of environmental relaxation at the lipid-water interface region of bilayer membranes.
Fluorescence of membrane-bound tryptophan octyl ester: a model for studying intrinsic fluorescence of protein-membrane interactions.
Homogeneous spectrally and time-resolved fluorescence emission from single-tryptophan mutants of IIA
www.biophysj.org /cgi/content/full/81/3/1825   (1654 words)

  
 Atomic-Fluorescence Spectroscopy   (Site not responding. Last check: )
Atomic fluorescence is the optical emission from gas-phase atoms that have been excited to higher energy levels by absorption of electromagnetic radiation.
The main advantage of fluorescence detection compared to absorption measurements is the greater sensitivity achievable because the fluorescence signal has a very low background.
The atomic fluorescence is dispersed and detected by monochromators and photomultiplier tubes, similar to atomic-emission spectroscopy instrumentation.
elchem.kaist.ac.kr /vt/chem-ed/spec/atomic/afs.htm   (176 words)

  
 Fluorescence spectroscopy proves capable of detecting inflammatory cells in blood vessels
An experimental time-resolved laser-induced fluorescence spectroscopy (TR-LIFS) device developed by researchers at Cedars-Sinai Medical Center was used to detect the presence of inflammatory cells in the aortas of animals, with results compared to those from pathology studies.
Laser-induced fluorescence spectroscopy is based on the fact that when molecules in cells are stimulated by light, they respond by becoming excited and re-emitting light of varying colors.
When these emissions are collected and analyzed (fluorescence spectroscopy), they provide information about the molecular and biochemical status of the tissue.
www.innovations-report.com /html/reports/life_sciences/report-47792.html   (598 words)

  
 Fluorescence and Fluorescence Excitation Spectroscopy   (Site not responding. Last check: )
The powerful technique of fluorescence excitation significantly enhances the capabilities of conventional fluorescence spectroscopy, which offers insights into chemical composition of the examined specimens.
In a conventional fluorescence measurement the excitation wavelength is fixed and the detection wavelength varies, while in a fluorescence excitation measurement the detection wavelength is fixed and the excitation wavelength is varied across a region of interest.
This is in contrast, with fluorescence at a single excitation wavelength or with wide band excitation (such as in a fluorescence microscope) which provides only partial information.
www.physics.mq.edu.au /~goldys/optmicroweb/Fluorescence/introduction.htm   (175 words)

  
 Principles of Fluorescence Spectroscopy: Joseph R. Lakowicz   (Site not responding. Last check: )
The approach is the same as that in the first edition: fluorescence spectroscopy from the viewpoint of a biophysical chemist.
The first three chapters ("Introduction to Fluorescence", "Instrumentation for Fluorescence Spectroscopy", and "Fluorophores") are an excellent brief (93-page) introduction to the whole field.
It would also be an excellent text for a graduate course on fluorescence in a chemistry or biochemistry department.
www.bookreviewsandsummaries.com /books/0306460939.htm   (280 words)

  
 Omni - X-ray Fluorescence
X-ray Fluorescence (XRF) Spectroscopy involves measuring the intensity of x-rays emitted from a specimen as a function of energy or wavelength.
As x-ray fluorescence involves transitions to inner electron states, the energy of characteristic x-ray radiation is usually unaffected by molecular chemistry.
In a gas, fluoresced x-rays are usually little affected by other atoms in the gas and line intensities are usually directly proportional to the amount of that atom present in the gas.
www.omniinstruments.com /fluorescence.html   (657 words)

  
 The Measurement of Sensitivity in Fluorescence Spectroscopy   (Site not responding. Last check: )
In fluorescence, the intensity of the emission of the sample is measured.
The sensitivity of fluorescence is dependent on both the fluorophore and the instrument.
In the case of a weak fluorescence signal, changing the bandpass will have little effect on the noise because it is due primarily to the dark count of the detector.
www.pti-nj.com /tech_3.html   (2922 words)

  
 Fluorescence Spectroscopy Identifies Kamut
Eric Dufour of Ecole Nationale d’Ingénieurs des Travaux Agricoles de Clermont-Ferrand, an agricultural and engineering university in France, thus has investigated whether a nondestructive spectroscopy technique he had used to categorize milk and cheese would be suitable for the identification of Kamut.
They employed a Fluoro-Max-2 spectrofluorometer from Horiba Jobin Yvon SAS of Longjumeau, France, in the experiments to excite an amino acid native to the grain and to observe the emitted fluorescence.
Similarly, differences in tryptophan fluorescence reflect both the normal variation between grains and the changes due to processing.
www.photonics.com /content/spectra/2006/May/spectroscopy/82577.aspx   (582 words)

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