Luminescence lasers

As mentioned earlier, the primary aim of this stndy was to nse changes in an intercalated dye s flnorescence intensity as a means to detect the presence of methanol vapor for the present stndy the highly luminescence laser dye C481 is chosen. Prior work has already shown that the flnorescence intensity of a closely related dye, cotrmarin 460, was dependent on the methanol concentration in solntion. ... 

The shapes of the interatomic potential curves are approximations chosen for mathematical convenience. Such potential functions are generally used in discussions on a variety of properties of molecules and lattices optical absorption and luminescence, laser action, infrared spectroscopy, melting, thermal expansion coefficients, surface chemistry, shock wave processes, compressibility, hardness, physisorption and chemisorption rates, electrostriction, and piezoelectricity. The lattice energies and the vibration frequencies of ionic solids are well accounted for by such potentials. On heating, the atoms acquire a higher vibrational energy and an increasing vibrational amplitude until their amplitude is 10-15% of the interatomic distance, at which point the solid melts. 

Radio-luminescence of transition metals doped natural beryl has been studied (Chithambo et al. 1995). It was found that Mn containing samples gave intense red radio-luminescence with sharp emission lines, while the Mn activated beryl (morganite) emission is more than twice as bright as that from emerald. Such luminescence has been ascribed to Mn " ", but it may be supposed that such emission is cormected with Mn luminescence. Laser-induced time-resolved luminescence spectra of natural morganite revealed band peaking at 730 nm, which may be prehminary ascribed to Mn" center (Fig. 4.122). 

Sol-gel derived materials with function of generating lights are listed under the heading of (A) Generation of light in Table 1-3. Actually, these materials convert a light to a new useful light by the use of luminescence, laser and non-linear optical effects. 

Lanthanide luminescence apphcations have already reached industrial levels of consumption. Additionally, the strongly specific nature of the rare-earths energy emissions has also led to extensive work in several areas such as photostimulable phosphors, lasers (qv), dosimetry, and fluorescent immunoassay (qv) (33). 

Fluorescence and phosphorescence are types of luminescence, ie, emission attributed to selective excitation by previously absorbed radiation, chemical reaction, etc, rather than to the temperature of the emitter. Laser-iaduced and x-ray fluorescence are important analytical techniques (see... 

Finally, an electric current can produce injection luminescence from the recombination of electrons and holes in the contact 2one between differendy doped semiconductor regions. This is used in light-emitting diodes (LED, usually ted), in electronic displays, and in semiconductor lasers. 

Photolysis, luminescent properties, and laser activity of coumarin derivatives 97MI27. 

D. Moses, High quantum efficiency luminescence from a conducting polymer in solution a novel polymer laser dye. Appl. Phys. Leu. 1992, 60, 3215. 

The immense growth in the luminescence literature during the period between these two reviews had little to do with developments in fundamental theory. It was mainly due to the availability of new instrumentation, such as the photomultiplier (around 1950), the laser (around 1960), transistor and microcircuit electronics (around 1970), and ready access to laboratory computers (around 1975). All aspects of luminescence theory now being used to interpret luminescence measurements have been known since the early 1900 s and nearly all of the types of measurements now being made had been initiated with cruder techniques by 1930. We discuss here many of the latest techniques in luminescence analysis with selected highlights from the historical development of luminescence and a look at several recent developments in luminescence applications that appear likely to be important to future research. 

Luminescence lifetime spectroscopy. In addition to the nanosecond lifetime measurements that are now rather routine, lifetime measurements on a femtosecond time scale are being attained with the intensity correlation method (124), which is an indirect technique for investigating the dynamics of excited states in the time frame of the laser pulse itself. The sample is excited with two laser pulse trains of equal amplitude and frequencies nl and n2 and the time-integrated luminescence at the difference frequency (nl - n2 ) is measured as a function of the relative pulse delay. Hochstrasser (125) has measured inertial motions of rotating molecules in condensed phases on time scales shorter than the collision time, allowing insight into relaxation processes following molecular collisions. 

Luminescence can be defined as the emission of light (intended in the broader sense of ultraviolet, visible, or near infrared radiation) by electronic excited states of atoms or molecules. Luminescence is an important phenomenon from a basic viewpoint (e.g., for monitoring excited state behavior) [1] as well as for applications (lasers, displays, sensors, etc.) [2,3]. 

Gratzel and co-workers found in their first flash experiments that the luminescence of CdS decayed with a lifetime of 0.3 ns When methyl viologen was present, the signal of the half-reduced electron acceptor, MV, was present immediately after the laser flash. With increasing concentration, the amount of MV formed... 

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