Excimer

Figure B2.3.9. Schematic diagram of an apparatus for laser fluorescence detection of reaction products. The dye laser is syncln-onized to fire a short delay after the excimer laser pulse, which is used to generate one of the reagents photolytically.

J and Vrepresent the rotational angular momentum quantum number and tire velocity of tire CO2, respectively. The hot, excited CgFg donor can be produced via absorjDtion of a 248 nm excimer-laser pulse followed by rapid internal conversion of electronic energy to vibrational energy as described above. Note tliat tire result of this collision is to... 

Figure C3.3.4 shows a schematic diagram of an apparatus tliat can be used to study collisions of tlie type described above [5, 9,12,16]. Donor molecules in a 3 m long collision cell (a cylindrical tube) are excited along tlie axis of tlie cell by a short-pulse excimer laser (typically 25 ns pulse widtli operating at 248 mil), and batli molecules are probed along tliis same axis by an infrared diode laser (wavelengtli in tlie mid-infrared witli continuous light-output...

CgFg molecules (CgFg - ) are produced at energy E = A 822 cnA by an excimer laser pulse (25 ns). 

Here is tire initial concentration of excited donor molecules produced at time t = 0 by tire excimer laser... 

An excimer is a dimer which is stable only in an excited electronic state but dissociates readily in the ground state. Examples of these are the noble gas dimers such as Hc2, discussed in Section 7.2.5.6. This molecule has a repulsive ground state but a bound... 

Excimer lasers employing NeF, ArF, KrF, XeF, ArCl, KrCl, XeCl, ArBr, KrBr, XeBr, Krl, and Xel as the active medium have been made. 

The method of excitation was, in the early days, by an electron beam but now a transverse electrical discharge, like that for the nitrogen laser shown in Figure 9.14, is used. Indeed such an excimer laser can be converted to a nitrogen laser by changing the gas. 

In an excimer laser the mixture of inert gas, halogen gas, and helium, used as a buffer, is pumped around a closed system consisting of a reservoir and the cavity. 

The examples of ArF (193 nm), KrF (248 nm), XeF (351 nm), KrCl (222 nm), XeCl (308 nm) and XeBr (282 nm) indicate the range of wavelengths from excimer lasers. Because the ground states of these molecules are not totally repulsive but very weakly bound, there is a very shallow minimum in the potential curve, as illustrated in Figure 9.15. In the case of XeF the potential energy minimum is relatively deep, about 1150 cm and supports a few vibrational levels. As a result the laser may be tuned over several transitions. 

The excimer laser radiation is pulsed with a typical maximum rate of about 200 FIz. Peak power of up to 5 MW is high compared with that of a nitrogen laser. 

Measurements of ozone concentration in the ozone layer in the stratosphere are made in the less intense Huggins band to avoid complete absorption of the laser radiation. Again, the two or three wavelength DIAL method is used to make allowance for background aerosol scattering. A suitable laser for these measurements is the XeCl pulsed excimer laser (see Section 9.2.8) with a wavelength of 308 nm, close to the peak absorption of the Huggins... 

Excimer lamp Excimer laser Excipients Excitation spectrum Exclamation Exclusion chart Exelderm Exelgyn... 

Fig. 40. Schematic of an euv exposure tool. Key features are the excimer laser-driven x-ray source and the redective optical elements (including the mask) in...

The requirements of thin-film ferroelectrics are stoichiometry, phase formation, crystallization, and microstmctural development for the various device appHcations. As of this writing multimagnetron sputtering (MMS) (56), multiion beam-reactive sputter (MIBERS) deposition (57), uv-excimer laser ablation (58), and electron cyclotron resonance (ECR) plasma-assisted growth (59) are the latest ferroelectric thin-film growth processes to satisfy the requirements. 

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