Excitation of fluorescence

Any factor that affects the size or shape of a molecule, the hindered movement of a fluorophore within a molecule, or the energy transfer within the molecule will affect the measured depolarization of its fluorescence emission. Therefore, the conformation of humic fractions in solution can be studied as a function of pH, ionic strength, temperature, and other factors by depolarization measurements. The principle of the method is that excitation of fluorescent samples with polarized light stimulates... 

Diaspro A, Robello M (2000) Two-photon excitation of fluorescence for three-dimensional optical imaging of biological structures. J Photochem Photobiol B 55 1-8... 

MacCraith B.D., Ruddy V., Potter C., O Kelly B., McGilp J.F., Optical waveguide sensor using evanescent wave excitation of fluorescent dye in sol-gel glass. Electron. Lett. 1991 27 1247. 

The tuneable nature of the evanescent field penetration depth is critical to the effective operation of this sensor as it facilitates surface-specific excitation of fluorescence. This means that only those fluorophores attached to the surface via the antibody-antigen-labelled antibody recognition event... 

Figure 5. A planar platform for evanescent-wave excitation of fluorescence.

While planar optical sensors exist in various forms, the focus of this chapter has been on planar waveguide-based platforms that employ evanescent wave effects as the basis for sensing. The advantages of evanescent wave interrogation of thin film optical sensors have been discussed for both optical absorption and fluorescence-based sensors. These include the ability to increase device sensitivity without adversely affecting response time in the case of absorption-based platforms and the surface-specific excitation of fluorescence for optical biosensors, the latter being made possible by the tuneable nature of the evanescent field penetration depth. 

H. Szmacinski, I. Gryczynski, and J. R. Lakowicz, Calcium-dependent fluorescence lifetimes of indo-1 for one- and two-photon excitation of fluorescence, Photochem. Photobiol. 58, 341-345 (1993). 

J. A. Lakowicz and S. Keating-Nakamoto, Red-edge excitation of fluorescence and dynamic properties of proteins and membranes, Biochemistry 23, 3013-3021 (1984). 

A. L. Stout and D. Axelrod, Evanescent field excitation of fluorescence by epi-illumination microscopy, Appl. Opt 28, 5237-5242 (1989). 

W. M. Reichert, J. T. Ives, P. A. Suci, and V. Hlady, Excitation of fluorescent emission from solutions at the surface of polymer thin-film waveguides An integrated optics technique for the sensing of fluorescence at the polymer/solution interface, Appl. Spectrosc. 41, 636-639... 

Carboxylic acids - I-pyrenyl diazomethane used as labelling reagent Excitation of fluorescent reagent at 340nm (emission at 395nm) 20- 30fmole [8]... 

Not illustrated is the use of multiphoton excitation of fluorescence (12.15). thus far demonstrated in flame systems only for excitation of atoms. It affords the means to excite otherwise inaccessible states and offers other potential advantages in spatial resolution and for optically thick flames, in spite of inherently low signal levels. 

This article shows how the evanescent wave can be used with advantage for spectroscopic purposes in the field of biomedical engineering. Three types of spectroscopy can be done with the evanescent wave in the UV-VIS range of the spectrum (a) attenuated total reflection (ATR) spectroscopy, which is well known in the infrared (b) the excitation of Raman scattering with the evanescent wave and (c) the excitation of fluorescence with the evanescent wave. The first two types will be discussed in this article the third is discussed for example by Hirschfeld U) and more recently by Watkins and Robertson (2). But before going into details a historical review may be of some interest. 

For the direct excitation of fluorescence from low-temperature samples of coal-derived materials, without prior separation steps, use of a laser as the source appears absolutely essential ( 2, 17). 

The molecular cross section of the ordinary Raman effect can be considerably enhanced. If the exciting radiation has a higher frequency, the intensity increases basically by the fourth power of the frequency. Moreover, there is a further increase as electronic absorption bands are approached the pre-resonance and resonance Raman effect (Sections 3.6 and 6.1). Further, the so-called surface-enhanced Raman effect (SERS) increases the molecular cross section. Both effects produce an enhancement of several orders of magnitude (Gerrard, 1991) (see Sec. 6.1). However, these two effects have to be carefully adapted to the specific properties of the investigated molecules. Photochemical decomposition and excitation of fluorescence may make it impossible to record a Raman spectrum. The described techniques may thus be of considerable importance for the solution of special problems, but they are by no means routine techniques to be generally used. 

Multiphoton Excitation of Fluorescence near Metallic Particles Enhanced and Localized Excitation. J. Phys. Chem. B 106 2191-2195. 

Lakowicz, J. R., and Gryczynski, I. (1999). Three-photon excitation of fluorescence. In Applied Fluorescence in Chemistry, Biology and Medicine, Rettig, W., Strehmel, B., Schrader, S., and Seifert, H. (Eds), Springer-Verlag, Berlin Heidelberg, pp. 137. 

How would you adjust the X-ray tube to ensure the excitation of fluorescence X-rays with energy of 15 keV Why should we choose appropriate target materials in the X-ray tube for XRF ... 

Govindjee, S Ichimura, C Cederstrand and E Rabinowitch (1960) Effect of combining far-red light with shorter wave lighten the excitation of fluorescence In Chlorella. Arch Biochem Biophys 89 322-323... 

Gryczynski I, Malicka J, Shen Y, Gryczynski Z, Lakowicz JR (2002) Multiphoton excitation of fluorescence near metallic particles enhanced and locahzed excitation. J Phys Chem B 106 2191-2195... 

The following quote from Paulfs paper is also essentially stiU correct today, for one can derive from a reading of the paper that his expression the lack of parallelism (s. below) meant the difference between the excitation spectra for photoemission and those for fluorescence, and the agitatiorf referred to the excitation of fluorescence ... 

J.A. Giordmaine, P.M. Rentze, S.L. Shapiro, K.W. Wecht, Two-photon Excitation of fluorescence by picosecond light pulses. Appl. Phys. Lett. 11,216 (1967) see also [11.26]... 

Hydrazones formed with Dns-H have fluorescence characteristics similar to those of the Dns-amides. Excitation of fluorescence can be achieved either at 360-370 nm or at 240 nm. Fluorescence emission is... 

Suitable systems for separation of the homologous series of aliphatic aldehydes have been worked out for all three lutidines [433, 435]. Excitation of fluorescence at 385 nm with emission measurement at 460 nm is suitable, although the derivatives of various aldehydes have slightly differing excitation and emission maxima. The detection limit is in the fmol range. 

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