Intensity exciting light

Emitted fluorescence may be optimized in a number of ways. To start with, high-intensity excitation light at the absorption maximum of the fluorochrome should be used. Second, lenses with moderate magnification and maximum numerical aperture (NA) are important. With epifluo-rescence illumination, the objective of the microscope serves as both the condenser and objective. Therefore, fluorescence intensity is proportional to the fourth power of its NA. 

In atomic emission, the decrease in emission intensity when light emitted by excited state atoms in the center of a flame or plasma is absorbed by atoms in the outer portion of the flame. 

The blue luminescence observed during cool flames is said to arise from electronically excited formaldehyde (60,69). The high energy required indicates radical— radical reactions are producing hot molecules. Quantum yields appear to be very low (10 to 10 ) (81). Cool flames never deposit carbon, in contrast to hot flames which emit much more intense, yellowish light and may deposit carbon (82). 

An ICP-OES instrument consists of a sample introduction system, a plasma torch, a plasma power supply and impedance matcher, and an optical measurement system (Figure 1). The sample must be introduced into the plasma in a form that can be effectively vaporized and atomized (small droplets of solution, small particles of solid or vapor). The plasma torch confines the plasma to a diameter of about 18 mm. Atoms and ions produced in the plasma are excited and emit light. The intensity of light emitted at wavelengths characteristic of the particular elements of interest is measured and related to the concentration of each element via calibration curves. 

With fluorescence, however, the sensitivity is limited in principle only by the maximum intensity of the exciting light source so that under ideal conditions,... 

Where I, andl are the measured intensities when the detector polarizer is respectively oriented parallel and perpendicular to the plane of the exciting light. 

Nonlinear optical phenomena, as well as near-field optics, provide us with super resolving capability [20]. The probability of nonlinear optical phenomena is proportional to the number of photons which participate in the phenomenon. For example, the intensity distribution of two-photon excited fluorescence corresponds to the square of the excitation light. Thus, we proposed a combination of the field... 

Using semiconductor sensors we examined several peculiarities of photoemission of C>2. It occurred that concentration of C>2 in gaseous phase exhibits a linear dependence on intensity of exciting light which is completely consistent with the Kautsky mechanism (see the experimental schematics). Moreover, these results indicate that in this case the readsorption processes (as well as local heating of sensibilizer) are not important. 

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