Abatement methods absorption


Excimer lasers (qv) generate pulsed light having very high iastantaneous peak powers. These lasers operate ia the deep ultraviolet (Duv) at 308, 248, and 193 nm, and have been found to cause laser-iaduced red fluorescence (658 nm), iaduced absorption, and structural compaction of vitreous siUca. The iaduced absorption at 215 nm is the same defect center generated usiag more energetic beams such as y- or x-ray. The subband gap light generated by excimer lasers excites electrons iato the valance band by a two-photon process. Transmission measurements made as a function of iatensity show that the two-photon absorption (TPA) coefficient is approximately (1.9-3.0) x 10 ° cm/W at 193 nm and 4.5 x 10 cm/W at 248 nm (213). The compaction and color-center formation also vary quadraticaHy with the laser fluence or iatensity and linearly with the number of pulses. The compaction causes a geometrical path decrease ia the material along with an iacrease ia the iadex of refraction (214). The iaduced absorptioa and compaction by excimer irradiation has been shown to reach a saturation poiat at about 0.1%/cm (215).  [c.511]


See pages that mention the term Abatement methods absorption : [c.287]   
Industrial ventilation design guidebook (2001) -- [ c.1263 ]