Intensity-time-wavelength surface

Figure 5. Schematic diagram of a time-resolved fluorescence spectrometer using a picosecond laser as an excitation source. Inset diagram intensity/time/ wavelength surface for poly (acenaphthalene) in benzene at 20°C. Excitation wavelength 295 nm. (Reproduced with permission from Ref. 21. Copyright 1987 Chemistry in Australia.)...

Repetition of the spectrum acquisition sequence at different probe-pulse arrival times provides a series of spectra delayed with respect to each other. Thus, time resolution of the reaction is achieved in a point-by-point manner, from which the intensity-time-wavelength surface can be produced. 

The most obvious characteristics of laser light are its brightness, its spectral purity, and the directionality of the beam. It is not so obvious how extreme these properties are. It has been pointed out ( 7) that a one-milliwatt He-Ne laser, virtually a toy laser, is 100 times brighter than the surface of the sun in terms of luminous intensity per unit area. Considering only light at the laser wavelength of 632.8 nm, the laser is 2 x 10 times brighter than the sun ... 

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