Diode Excitation

A disadvantage of laser diodes is that they are presently available only with red and NIR wavelengths above 630 nm. Green and blue laser diodes are under development but ere not yet available. Fortunately, it is now known that 

The use of a simple U t source idi as an LED is likely to find use in analytical chemistry and clinical diemistry. This is illustrated in Hgure 5.48, which shows the frequency re nse of the pH probe SNAFL-2 measured with 

Another applicatitm of LEDs will be for excitadem of the longer-lived metal—Uguid complexes (Chapter 20). The 

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J. Hicks, D. Andrews-Wilberforce, and G. Patonay, A near-infrared laser diode excitation source for an SLM 8000CI luorometer, Anal. Instrum. 19,29-47 (1990). 

P. A. Johnson, T. E. Barba , B. W. Smith, and J. D. Winefordner, Ultralow detection limits for an organic dye determined by fluorescence spectroscopy with laser diode excitation, Anal. Chem. 61, 861-863 (1989). 

A. Measurement of Human Serum Albumin with Laser Diode Excitation... 

In the future, we can expect the ratho expensive picosecond dye lasers and Ti sapphire lasexs to be t laced by sin ler and less eiq>ensive device. A diode-punq>ed Nd YAG laser has already been used fw Ume-resolved detection in capillary zone eleftto(4ioresis, and one can purchase a streak camera with apulsed lasCT diode excitation source. Laser diodes have also been used as the excitation source for FD fluwiMnctry. The wavelengths are usually limited to 600-700 nm, but some laso diodes can be frequency-doubled to 410 nm. It is also likely that... 

Xu. W.. Kneas, E Am Oenas. J. N sod DeOrair. E A- 1996. Oxygen sensors baaed on Inuunescence quenddng of metal complexes Osmium conqdexes suitable for iaser diode excitation, Anol. 

A clear example of three-body upconversion is the Do Fj Eu " emission in Y2O3 rEu ", Yb upon 970 nm laser diode excitation into the %/2 multipletof Yb [145]. The schematic energy level diagram is shown in Fig. 13a, where the lowest F5/2 and Di energies are (in cm ) 10,225 and 18,937, respectively. The two-photon namre of the process is confirmed by the emission intensity-laser power plot in Fig. 13b. It is observed that the Eu " emission intensity increases considerably with temperature in the range from 10 K up to room temperature (Fig. 13c) and this was accounted for by two simulations. One of these simulations was based upon the thermalization of the Fi levels of Eu ", whereas the alternative simulation focused on the dependence of upconversion rate upon temperature [145]. 

As the luminescent centers D and A are codoped in a phosphor, energy transfer may allow both D and A to emit, thus generating two color emissions on a single color excitation. Such a doubly doped system, or even triply doped system, exhibits attractive application for fiiU-color white-light generation on blue and/or UV LED (light-emitting diode) excitation. 

A. Owyoung, G.R. Hadley, P. Eshericle Gain switching of a monolithic singlefrequency laser-diode-excited Nd YAG laser. Opt. Lett. 10, 484 (1985)... 

Allen, T.J. and Beard, P.C. (2005) Pulsed near-infrared laser diode excitation system for biomedical photoacoustic imaging. Optics Letters, 31, 3462-4. 

ConnaUy R., J. Piper. Sohd-state time-gated luminescence microscope with ultraviolet light-emitting diode excitation and electron-multiplying charge-coupled device detection, J. Biomed. Opt., 13, 034022-1 to 034022-6 (2008). 

Dual wavelength laser diode excitation source for 2D photoacoustic imaging, T. J. Allen and P. C. Beard, Proc. SPIE, 2007, 6437, 64371U/1. 

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