J. H. Jacob

Improvement in XeF laser efficiency at elevated temperatures

Improvement in e‐beam‐pumped XeF laser efficiency is reported when the laser is operated at temperatures above 300 °K. The improvement is due predominantly to improved energy extraction from the upper laser level as well as decreased lower level lifetime. The highest intrinsic laser efficiency (laser energy out/e‐beam energy deposited in the active medium) observed at 3 amagats and 450 K is 5.5%. The temperature at which the highest efficiency is achieved is observed to increase with increasing gas density.

Accessibility of the KrF*(B) state to laser photons

Using electron beam excitation of Ar/Kr/F2 mixtures in a 1‐m laser, we monitored KrF*(B) sidelight fluorescence of the 249‐nm B→X transition. Comparing signals observed in the presence and absence of cavity flux, we evaluated the ability of the photon field to depopulate the upper laser level by stimulated emission. From these experiments, we concluded that some of the KrF* population was in higher vibrational levels and could not be effectively extracted by stimulated emission at the normal laser operating wavelength.

Electron quenching of KrF* and ArF*

The collisional deactivation by electrons of the upper laser levels of KrF* and ArF* has been measured. The rare‐gas/fluorine binary mixtures were excited by a beam of fast electrons. These electron beam pulses were long enough to allow the use of a steady‐state analysis of the fluorescence. Quenching rate constants near 2×10−7 cm3/sec have been obtained.

Electron dissociative attachment rate constants for F2 and NF3 at 300 and 500 °K

Electron attachment to F2 and NF3 has been studied in an electron‐beam‐controlled gas‐discharge apparatus over a range of E/P (2–10 kV/cm atm). These experiments were performed in gas mixtures containing small amounts of the halide molecules (≲1%) in an atmosphere of N2 which was included to control the average electron energy. We obtained values for the rate constants for dissociative attachment to F2 and NF3 as a function of mixture temperature at 300 and 500 °K and applied electric field. These results compare favorably with the rate constants deduced from the absolute cross section for these compounds reported by Chantry.

Electron and heavy particle temperature dependent quenching rate constants of XeF

Two and three body quenching rate constants were determined at 300 and 500 °K for a number of quenching gases common to XeF* laser mixtures (Ne, Xe, F2). Among these is the three body quenching of XeF4 by F2 and Xe. In addition, the quenching rate for the reaction XeF*+e− was measured and this process was found to be one of the major quenching channels under typical laser operating conditions.

Surface catalyzed reaction of Hg + Cl2☆

Abstract An investigation of the reaction of mercury atoms with molecular chlorine was performed in heated reaction vessels constructed of Inconel, quartz, stainless steel and Teflon-coated stainless steel. The reaction was shown to proceed as a surface catalyzed reaction stoichiometrically producing (HgCl 2 ) n .

The effect of ground state population on the XeF laser performance

In this letter we describe an investigation of the effect of the bound ground state of XeF on the laser performance. This was accomplished by observing the intensity of the sidelight fluorescence of the B (v′=0) →X (v″=3) as a function of laser flux at 353 nm. Our data indicate that the ground state dissociates more rapidly as the laser mixture temperature is increased from 300 to 500 °K. As a result of the faster dissociation rate at 500 °K, the XeF laser efficiency increases by ≈1.5 as the mixture temperature is increased from 300 to 500 °K.

The origin of the broadband emission of XeF

In this letter we report the results of our investigation into the origin of the broadband emission, centered about 460 nm, from XeF*. This emission has been investigated as a function of mixture ratio and pressure. The gas mixtures were excited by a high‐energy electron beam. From the high‐pressure data there is evidence of additional emission from states other than XeF(B) and XeF(C) when the buffer gas is Ar and Ne. We have tentatively assigned this emission as originating from the excited triatomics ArXeF* and NeXeF*.