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Topic: Stokes shift

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In the News (Thu 24 Jul 14)

  NFM - Stokes shift
Stokes shift is the distance between the peak absorption and peak emission wavelengths.
The emitted wavelength is always longer (if single photons are absorbed) or equal to the incident wavelength, due to energy conservation; the difference is absorbed as heat in the atomic lattice of the material.
It is named after Irish physicist George G. Stokes.
www.nanofm.com /terms/stokes_shift.html   (72 words)

This red shift is reffered to as the Stokes shift and its origin, magnitude and size dependence is a notable source of controversy, especially for silicon nanoclusters.
The figure to the left is a schematic of the Stokes shift.
The Stokes shift is the difference in energy between the initial absorption and the final emission photons.
www-phys.llnl.gov /Research/qsg-090205/siliconDots_stokes.html   (1067 words)

 Olympus FluoView Resource Center: Fluorescence Excitation and Emission Fundamentals
In practice, the Stokes shift is measured as the difference between the maximum wavelengths in the excitation and emission spectra of a particular fluorochrome or fluorophore.
For example, the Stokes shift for fluorescein is approximately 20 nanometers, while the shift for quinine is 110 nanometers (see Figure 4) and that for the porphyrins is over 200 nanometers.
The existence of Stokes shift is critical to the extremely high sensitivity of fluorescence imaging measurements.
www.olympusfluoview.com /theory/fluoroexciteemit.html   (3559 words)

 George Gabriel Stokes Summary
Sir George Stokes, who was made a baronet in 1889, further served his university by representing it in parliament from 1887 to 1892 as one of the two members for the Cambridge University constituency.
Stokes was the oldest of the trio of natural philosophers, James Clerk Maxwell and Lord Kelvin being the other two, who especially contributed to the fame of the Cambridge school of mathematical physics in the middle of the 19th century.
Stokes, however, in a letter published some years after the delivery of this address, stated that he had failed to take one essential step in the argument—not perceiving that emission of light of definite wavelength not merely permitted, but necessitated, absorption of light of the same wavelength.
www.bookrags.com /George_Gabriel_Stokes   (1602 words)

 Nikon MicroscopyU: Introduction to Fluorescence Microscopy
British scientist Sir George G. Stokes first described fluorescence in 1852 and was responsible for coining the term when he observed that the mineral fluorspar emitted red light when it was illuminated by ultraviolet excitation.
As a result of the energy loss, the emission spectrum of an excited fluorophore is usually shifted to longer wavelengths when compared to the absorption or excitation spectrum (note that wavelength varies inversely to radiation energy).
As Stokes' shift values increase, it becomes easier to separate excitation from emission light through the use of fluorescence filter combinations.
www.microscopyu.com /articles/fluorescence/fluorescenceintro.html   (5489 words)

 Light Microscopy Facility
Stokes identified the phenomenon of fluorescence in the mid 19th century, and the first fluorescence microscopes were developed at the beginning of the 20th Century.
This is known as Stokes Law, and the difference in emission wavelength relative to excitation wavelength is called Stokes shift (see Fig 2).
Stokes shift varies among different fluorophores, so not only do fluorophores have characteristic excitation spectra, they have characteristic emission spectra as well (see Wang and Lansing Taylor, 1989 and Lakowicz et al., 1992).
www.dundee.ac.uk /lifesciences/microscopy/lmf/flintro.htm   (1206 words)

 J. Stokes & Associates -
Stokes and Associates provides communications services to companies that are ready to activate positive change.
To initiate awareness, to shift opinion, to capture the lead.
Achieving positive results requires the devotion of a talented team that can connect your brand with its ideal audience.
www.jstokes.com /index.php?page=p-about   (125 words)

 Photonics.com Printer Friendly View
In Raman spectroscopy, a small portion of the laser radiation that strikes a molecule scatters and is red- or blue-shifted by an amount equal to a vibrational quantum of energy.
The red-shifted Stokes scattering occurs whether or not the molecular vibrations are excited, but the blue-shifted anti-Stokes scattering is only observed from vibrations in excited states.
Specifically, in anti-Stokes, the excited molecule loses some of its vibrational energy in the form of photons with higher energy than the incoming ones, and the intensity of the shift is directly related to the amount of energy in that particular vibrational state.
www.photonics.com /printerFriendly.aspx?contentID=79672   (528 words)

 Tom Obsil's Page - Fluorescence Spectroscopy
This red shift is due to a change in the local environment of the excited state during it's lifetime.
The magnitude of the Stokes shift depends on the polarity of the solvent.
Note that shifts of this type are also seen in absorption spectroscopy, but in that case they are a reflection of stabilization of the empty excited state orbital.
members.tripod.com /obsil/fluor.html   (3220 words)

 History of Recognition - Bites of History - 50 Years of SPIE - SPIE Web   (Site not responding. Last check: )
Stokes' work was primarily in mathematics and physics, and is known now through terms such as Stokes Law, Stokes Phenomenon, Stokes Theorem, and the Navier-Stokes equations.
His greatest advances were related to the wave theory of light and the mathematical theory of diffraction, as well as fluorescence (the "Stokes shift"), spectrum analysis, and the dynamical theory of double refraction.
The G. Stokes Award is given for exceptional contribution to the field of optical polarization and is sponsored by ITT Industries, Hinds Instruments, L3 Communications, Meadowlark Optics, and Russell Chipman.
www.spie.org /50years/index.cfm?fuseaction=awards   (1815 words)

 Avalon Instuments - Raman Background Information
Raman peaks on the Stokes side are intense, as they arise from molecular vibrations which arrise from energy transfer from the photon to the molecule.
Anti-stokes peaks have the same wavelength shift as stokes but they involve an transfer of energy from an vibrating molecule into a photon, obviously as a vibrating molecule is requires this is a quite rare event, as a result of this Anti-stokes spectra are weak.
One andvnatge of collecting anti-stokes spectra is that the ratio of stokes and anti-stokes offers an insight into the Bolzmann distribution and so can be used to tell the temperature of the samples at the point of laser irridiation.
www.avaloninst.com /content/raman_information   (619 words)

 European Journal of Mass Spectrometry - Abstract of Wavelength- and time-resolved luminescence spectroscopy for ...
Matrices showing a high Stokes shift dissipated high amounts of laser energy by means of intra- and intermolecular energy transfer processes, hence contributing less to the ionization of analyte compounds.
Conversely, matrix substances with a low Stokes shift retained more of the original photonic energy which may then be available for ionization within the matrix or after desorption of molecular species.
Therefore matrix compounds can be designated as "hard" (high ionization energy) in the case of small Stokes shifts or "soft" (low ionization energy) in the case of high Stokes shifts.
www.impublications.com /abstract/E08_0287   (223 words)

 Red shift of a distant super cluster of galaxies
The shift in the spectrum of BAS 11 from the spectrum of the sun is clearly seen.
The lines from BAS 11 are all shifted towards the red end of the spectrum.
This shift (called the "red shift") is toward longer wavelengths (smaller frequencies) and is caused by the Doppler effect.
stokes.byu.edu /redshift.html   (297 words)

 Effect of lesions on the dynamics of DNA on the picosecond and nanosecond timescales using a polarity sensitive probe ...
Stokes shift amplitudes indicate that the interior of DNA is a polar environment
shift is an average of the time-resolved shift that is strongly
Time-resolved relative Stokes shift for the chain-end sequence 3 (squares) compared with the shift in the normal sequence 1 (circles).
nar.oxfordjournals.org /cgi/content/full/32/8/2494   (8183 words)

 Sergei Arzhantsev — Department of Chemistry   (Site not responding. Last check: )
The connection between polar solvation dynamics as measured by dynamic Stokes shift experiments and the friction on charge transfer reactions has been appreciated since the early 1980.
Measurements of the dynamic Stokes shift of DCS (trans-4-dimethlamino-4’-cyanostilbene) in polar solvents show a good correlation with the corresponding dynamics previously reported using the solvatochromic probe C153 (coumarin 153).
This transition causes a large decrease of fluorescence intensity and a simultaneous solvation induced red shift of the emission spectrum.
www.chem.psu.edu /faculty/sxa42   (663 words)

 stokes shift
Stokes shift is the difference (in wavelength or frequency units) between positions of the band maxiAndere Farbstoffe zeigen eine große Verschiebung der Fluoreszenz relativ zur Absorption (großer StGKN has gone live with Fourth Shift in its Sheepbridge Stokes site in Chesterfield, UK.
Stokes shifOn Stokes shift Stokes shift is the 8 internal hub, eight derailleur, 24 Shimano Intego Hub hub.
Stokes Shift   The diffeStokes shift (′stōks ′shift) (spectroscopy) The displacement of spectral lines or bands of Detecting Cancerous Tissue via Stokes Shift Emission Spectroscopy Detecting Cancerous Tissue via Sto4 Vibrational dynamic Stokes shift in liquid water 4.1 Introduction It was discussed in Chapter 1 th
www.wavenetwork.org.uk /23239   (585 words)

Where fluorescent materials are used as detectable labels a large Stokes shift is often highly desirable because it makes life easier when optical filters are used to separate exciting light and fluorecence emission.
Fluorescent labels with very large Stokes' shifts include lanthanide complexes of europium and terbium that are excited in the near ultraviolet region and emit in the orange/red and green spectral regions respectively.
These molecules have large shifts because their excitation processes are mediated by energy relay mechanisms from triplet states of ligands bound to the lanthanide ions.
www.prsbio.com /html/faq.html   (8919 words)

 Olympus Microscopy Resource Center: Physics of Light and Color
Fluorescence - The phenomenon of fluorescence was known by the middle of the nineteenth century.
Stokes observed that the fluorescing light has longer wavelengths than the excitation light, a phenomenon that has become to be known as the Stokes shift.
Fluorescence microscopy is an excellent method of studying material that can be made to fluoresce, either in its natural form (termed primary or auto fluorescence) or when treated with chemicals capable of fluorescing (known as secondary fluorescence).
www.olympusmicro.com /primer/lightandcolor   (2216 words)

 Jones & Stokes Impact Report Archive
EDT is currently being used in the majority of the major watersheds in the Pacific Northwest to develop watershed and fish recovery plans, identify factors limiting salmon production, and to evaluate alternative restoration strategies.
In April, Jones and Stokes received three awards from the California Association of Environmental Professionals, including the coveted "Outstanding Environmental Analysis Document,” and an award for documenting the little-known history of African-Americans in downtown San Diego.
Jones and Stokes was singled out by representatives of the U.S. Bureau of Reclamation and the U.S. Fish and Wildlife Service for its pivotal role in the development of the largest river habitat conservation plan ever completed under the Endangered Species Act.
www.jonesandstokes.com /Newsletters/ImpactReportArchive.htm   (1559 words)

 Mark R. Abel   (Site not responding. Last check: )
It is shown that a simple calibration of the Stokes shift with temperature yields a linear calibration for measurements up to 1000 ° C in polycrystalline Si.
The Stokes peak was also shown to shift linearly with an applied pure bending stress.
Thus in order to evaluate temperature without the influence of thermally induced stresses which may evolve in some MEMS, the ratio of the Stokes to anti-Stokes signal intensities and the linewidth of the Stokes spectral band were calibrated for doped Polysilicon over the same temperature range.
www.me.gatech.edu /me/theses/abelmtp7-12-05.htm   (403 words)

 Fluorophore Characteristics: Making Intelligent Choices
The field of DNA typing is rapidly shifting towards the use of fluorescence-based detection methods in a wide variety of applications.
The Stokes shift is the difference in wavelength between the fluorescence excitation maximum and the fluorescence emission maximum.
Interestingly, in general, dyes with large Stokes shifts tend to have relatively small extinction coefficients, whereas dyes with small Stokes shifts tend to have relatively large extinction coefficients.
www.promega.com /geneticidproc/ussymp8proc/21.html   (2455 words)

 (10th Anniversary Essays) 4. Detection technologies (IVDT archive, Apr 05)
The resonance shifts the reflectance maxima (angle difference), and the reflectance determines the quantity of binding on the surface.
The greater the Stokes shift, the greater the ability to discern the two bandwidths.
In either case, the Stokes shift is large, and it is easy to distinguish between the emission from a first chromophore and a second chromophore.
www.devicelink.com /ivdt/archive/05/04/006.html   (2424 words)

The dynamics are investigated by monitoring the time-resolved Stokes shift of a suitable probe molecules dissolved in the solvent mixture.
Changing systematically the viscosity the non-polar component (length of alcane chain) and the size of the polar solvent molecules (different kind of alocohol molecules) as well as the concentration of the polar component the influence of these parameters on the solvation dynamics was studied.
This change in electrostatic energy is responsible for the additional shift and broadening of the static absorption (or fluorescence) spectra.
www.tu-chemnitz.de /physik/OSMP/CPS/Schwerpunkte_e.html   (833 words)

 Physikalisch-Technische Bundesanstalt (PTB)
The specimen under investigation is illuminated by two light fields, called pump and Stokes signal.
This results in the emission of a so-called anti-Stokes (AS) signal which is blue shifted with respect to the pump signal.
Because CARS is a coherent four-wave-mixing process, such a heterodyne detection becomes practicable as soon as an LO with a fixed phase relationship to pump and Stokes fields is available.
www.ptb.de /en/org/4/45/453/hodyn_e.htm   (864 words)

 Sacher Lasertechnik Group - Raman Spectroscopy
The purity of the laser light is increased by a notch filter before it is coupled to the sample.
There it interacts with the sample and in result, the signal according to the Stokes and Anti-Stokes Shift is generated.
With removing the central wavlength of the laser light by an optical filter, the shift of the raman signal can be determined by the spectrometer.
www.sacher-laser.com /raman.php   (225 words)

 Effect of Protein Binding on Ultrafast DNA Dynamics: Characterization of a DNA:APE1 Complex -- Sen et al. 89 (6): 4129 ...
is stabilized, the fluorescence from the chromophore shifts
shifted relative to the spectrum in water is one piece of evidence
The steady-state Stokes shift in DNA is significantly smaller
www.biophysj.org /cgi/content/full/89/6/4129   (5427 words)

 Stokes Shift
Scaling of fluorescence Stokes shift and superradiance coherence size in disordered molecular aggregates.
Fluorescence line shapes and cooperative spontaneous emission in disordered one-dimensional molecular aggregatesare calculated using closedexpressions derived by applying the method of optimal fluctuation.
Scaling of the Stokes shift with aggregate size, and the time-dependent Stokes shift are discussed as well.
dft.rutgers.edu /~etsiper/stokes.html   (316 words)

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