KrF laser

Draw a diagram similar to that in Figure 9.21 to illustrate the stimulated Raman effect in FI2. Fligh-pressure FI2 is used to Raman shift radiation from a KrF laser. Calculate the two wavelengths of the shifted radiation which are closest to that of the KrF laser. 

Figure 1. Transient IR spectra following photolysis of Fe(C0>5 with XeF and KrF laser radiation. Traces are taken -1 nsec after photolysis. In addition to Fe(C0>5 (30 mtorr for KrF, 200 mtorr for XeF) the photolysis cell contained 5 torr Ar. The symbols are defined in the text.

Note added in typing In a very recent paper (81) Vaida and co-workers have used picosecond laser photolysis to show that, in cyclohexane solution, Cr(CO)5...cyclohexane (Amax 497 nm) is formed within 25 ps of the photolysis of Cr(C0)5 This suggests that, in solution, the primary photoproduct is Cr(C0)5 and that there is essentially no activation energy for the reaction of Cr(C0)5 with the solvent. Clearly, experiments with pulsed KrF lasers on carbonyls in solution and matrix may be very revealing. 

Krypton fluorocationic salts, 17 333 Krypton lasers, 14 684. See also KrF laser in laser light shows, 14 688 Krypton-xenon, purification and separation of, 17 361-362 Krypton-xenon column, 17 359, 360 Kubelka-Munk equation, 7 317-318 14 231 23 127... 

Figure 10. T (248 nm) vs. E (248 nm, KrF laser) under N2, for 25% DPA/PPSQ/0.075% Kc450, previously exposed under 02 at 476 nm to the T248 shown. Excimer laser pulse rep rate 25 pps, delivered in bursts of 10 or 100.

The transition to the C B- state of H 0 was achieved by a two photon absorption of KrF laser light near 248 nm (32). The OH(A-X) fluorescence excitation spectrum in the 247.9-248.5 nm range follows the rotational structure of the C B -+ X A transition. However, (i) the OH(A-X) fluorescence spectrum produced by the two photon dissociation of H 0 has a maximum population at N = 14, while single photon absorption near 124 nm generates OH fluorescence spectrum with a maximum population at N = 20 (ii) only absorption to Ka= 1 (and not Ka= 0 where K is the rotational angular momentum about the a axis) of the ClB-L state predissociates into 0H(a2%) + H probably through the B A state. Apparently, the two-photon absorption near 248 nm predominantly populates the c b state, while the single photon process populates the B A near 124 nm. 

Photodissociation dynamics of this molecule were studied using the TOF technique to determine the velocity distribution of the fragments when the molecule is photolyzed with a KrF laser at 248 nm (182). Absorption at this wavelength leads to the excitation of the second singlet state, the B- -Ai state, from the X A ground state. From the TOF spectra of the CS fragment they were able to show that both of the following reactions occur ... 

A laser beam was used for graft polymerization of AAc onto a tetrafluo-roethylene-perfluoroalkyl vinyl ether copolymer film [81]. The film placed in contact with AAc solution was irradiated with KrF laser through the film to excite the film/solution interface. Surface composition of the grafted film determined by XPS revealed an extensive loss of fluorine atom and an increase of oxygen atom in addition to the presence of a Cls line shape, similar to that of AAc monomer. Mirzadeh et al. [82] used pulsed laser beam for the graft polymerization of AAm on a rubber surface in the presence of a photosensitizer, ben-zophenone, or AIBN. 

BrC2F4Br KrF laser or Xe lamp or low P Hg lamp RT variable according to light source 73... 

Figure 2. Growth of the absorption due to the formation of (SCNV at intervals ranging from 40ns to 800ns after the laser pulse. (KrF laser, excitation wavelength 248nm, [H202]= 50mM, [SCN-] = 0.5mM)...

Off-axis and dual laser PLD for droplet reduction Dynamic melt studies of the target surface, time synchronized irradiation of the target with CO2 and KrF lasers leads to particulate free ZnO films [133,134]... 

Laser-induced decomposition of mixtures of polychlorinated biphenyls in the liquid phase has been investigated, employing radiation from three different excimer lasers (XeCl at 308 nm, KrF at 248 nm and ArF at 193 nm)475. The mixtures can be quantitatively and efficiently destroyed by means of UV radiation at 248 nm. A single-photon dissociation process, which leads to both HC1 elimination and biphenyl bond rupture, is induced by the KrF laser radiation. 

Chemical amplification type positive resist compositions provided in Table 1 were prepared by Takemoto [4] and were suitable for excimer laser lithography using ArF and KrF lasers. 

Synthetic routes to these complexes are summarized in Table XIII, which also lists the spectroscopic studies that have been made on this class of complexes. The action of PF3 or CO usually under pressure with simultaneous UV irradiation on metal carbonyls or metal trifluorophos-phine complexes, respectively, is of general applicability (method A). More recently, photolysis using a KrF laser has also been utilised, e.g.,... 

Figure 5. Transmittance of KrF laser pulses (35nsec nominal FWHM) vs. integrated dose, at various incident intensities (in MW/cm2), for a 4.2ym film of PAMA 2 on quartz. The higher intensity pulses (5.1 MW/cm2 and above) were delivered singly at lower intensities they were delivered in bunches of 10 or 100 at 25Hz. For such bunches, the transmittance recorded is the average over the bunch. In all cases, the data in the threshold region came from single pulses.

A large number of papers has appeared on the subject of excimer laser exposure of polymer films (16-21). Most of these have dealt with the phenomenon of photoablation. A few have observed intensity dependent photochemistry (22,23). The latter authors were concerned with the effect of exposure intensity on resist development characteristics. The utility of nonlinear photochemistry for image modification has not been explored except in our earlier communication, in which strongly nonlinear irreversible bleaching was observed for KrF laser irradiation of acridine/PMMA films with lOnsec pulses (5). 

Most resists are designed for exposure at wavelengths longer than the 248.4 nm radiation provided by a KrF laser source. Wolf and coworkers O) have found that the choice of a positive resist for use at thTis wavelength is limited. They evaluated a number of positive resists. Only Microposit 2415, and its newer analog, Microposit 2400-17, were compatible with the anticipated exposure time of 0.5 to 1.0 seconds for resist sensitivity of 100 to 200 mj/cm needed with the new exposure tool developed by Pol and coworkers. (O The resist consists of three components a resin, a photoactive compound or PAG (which acts as a dissolution inhibitor), and a solvent. Upon exposure, the PAC is destroyed, and this allows the resist film to dissolve in the aqueous basic developer. 

Laser-induced chemical hquid deposition of copper fihns on qnartz and glass from Cn(acac)2 (7a) as precnrsor was reported by Onchi and collaborators 2. The process is realized throngh the interaction of copper coUoids with the appropriate snrfaces. It was fonnd that, depending on whether the laser irradiation is discontinnons (ArF laser) or continnons (KrF laser), closed copper fihns or nano-islands were formed. This method differs from the laser-assisted liqnid-phase metallization of polymers, wherein a laser beam was nsed to enhance chemical rednction of copper(II) salts. ... 

Fig. 5. Resonance enhanced, two-photon spectrum of rotationally relaxed NO produced in reaction (18) initiated by the KrF laser...

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