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We present a novel photolytic nuclear pumping scheme, utilizing concentration of nuclear‐pumped excimer fluoresccence and a new high‐efficiency nuclear pumping source that overcomes nuclear pumping’s previous problems of insufficient pumping power density and the deleterious effects of nuclear pumping sources on laser kinetics. Utilizing this scheme should produce absorbed pumping power densities of 50‐100 kW/cm3 in the photolytic laser medium‐more than sufficient for long pulse pumping of efficient excimer and excimer like laser systems. Laser system efficiency should exceed 1%.

The photo‐etching characteristics of photoresists for excimer lasers were investigated and compared with those for uv lamps. Uniform intensity irradiation system for micro‐electronics processing is demonstrated.

Stimulated Raman scattering experiments in hydrogen were performed using long pulse (0.4 ..mu..sec) e-beam pumped XeF lasers. The intent was to maximize conversion to second Stokes wavelengths in the blue-green (500 nm). Narrow, collimated pump beams were used in order to minimize four-wave processes by keeping the aspect ratio of the pumped volume below the phase matching angle. Conversion was determined as a function of intensity by varying the pump beam diameter in the hydrogen cell and as a function of path length by varying the length of the cell. A maximum conversion of greater than 40% was observed. No anti-Stokes radiation was seen, indicating that four-wave processes were not significant with this collimated geometry.

Chemically pumped CO is studied as a medium for tunable, VUV anti‐Stokes Raman laser emission. Raman scattering of excimer and tunable UV lasers has been observed from 135 nm to 170 nm.

Two and three photon ionization of Xe has been studied using excimer lasers. Employing a microwave bridge to determine the temporal behavior of the absolute photoelectron density, the cross‐section for two photon ionization of Xe at 193 nm has been measured to be (4±1)⋅10−32 cm4−W−1. An order of magnitude improvement in the peak electron density is realized by ionizing Xe with two XeF (351.1 nm) and one ArF (193.3 nm) photons. This process is resonantly enhanced by the 6p[1/2]0 level of Xe. The strong, selective pumping of this state has resulted in the observation of stimulated emission on the Xe {6p[1/2]0→6s[3/2]11} transition at 828.0 nm−the first optically pumped rare gas laser.

For several years transverse discharge excited excimer lasers (RGH-lasers) have been recognized as the laser source in the UV spectral range. The variety of wavelengths available make them very attractive especially for photochemical applications. In addition, the XeCl laser (308 nm) has been found to be particularly well-suited for pumping dye lasers. A growing interest in the VUV spectral range as well as for XUV wavelengths has led to a number of experiments in which the wavelength of the excimer laser is transferred to the VUV by non-linear processes such as harmonic generation, mixing with dye lasers or parametric processes. A major drawback of conventional excimer lasers for the latter application is the poor quality of their beam divergence and spectral brightness. An excimer laser with high spectral brightness is discussed.

The spectroscopy and kinetics of electron beam‐pumped broadband triatomic excimers will be reviewed. Laser considerations such as gain and absorption effects will be discussed, with emphasis on Xe2Cl.

Excimer lasers, while able to produce large powers and energies, are limited to a few discrete wavelengths. Efficient Raman shifting promises the availability of a much broader wavelength range. A method was developed which both Raman shifts and allows for multiple pump beams.

This paper describes a high power KrF laser pumped by multiple electron beams. Laser triggered switching is used to synchronize the beams to a few ns. Up to 10 kJ in a 60 ns pulse is switched out from four pulse forming lines using less than 20 mJ of KrF radiation. An unstable resonator is used with a four pass injection scheme which results in ≳200 J output at 249 nm in a low divergence beam.

The tuning and saturation behavior of the anti‐Stokes Raman laser is examined experimentally for the first time in a Raman medium of inverted, metastable T1* (6p 2P03/2). Two significant regions of saturation are identified corresponding to atomic saturation and pump depletion of the input laser field.

A unique, x‐ray preionized, electric discharge‐excited XeCl laser was designed, constructed and optimized for the purpose of demonstrating high laser efficiencies. Several parallel‐plate water pulse‐forming networks (PFNs) were evaluated experimentally. A parametric study was performed with a douBle‐sided blumlein configuration and was supported by computer modeling.High energy transfer efficiency from the PFN to the discharge plasma requires fast avalanche discharge formation as well as good impedance matching between PFN (source) and discharge (load). This paper establishes the fact that conventional PFNs cannot satisfy these two conditions simultaneously. By employing a separate pulse for breaking down the gas quickly and an impedance‐matched pulse forming line for transferring most of the pump energy, the transfer efficiency was almost doubled, and the laser efficiency goal of 3% was exceeded.

Excimer lasers are stabilized using electrodes with series stabilizing inductors. Intrinsic efficiencies as high as one percent are obtained in the miniature laser systems and laser pulse widths as long as 120 ns are observed.

Absorption of VUV and XUV radiation leads not only to highly excited electronic states of a molecular system but also to phenomena such as photofragmentation and photoionization. Progress in this field will be reviewed with particular emphasis to the possibilities opened by the advent of XUV and VUV coherent sources.

The small signal gain coefficient, the saturation intensity, and the absorption coefficient of an electron‐beam pumped KrF laser were measured by a probe laser at pumping rates of 0.9−1.5 MW/cm3 and pressures of 1140−1900 torr. Half reduction of the absorption coefficient was observed at the probe laser intensity of more than the saturation intensity. The experimental data was compared with a laser kinetic simulation and good agreement was observed.

Observation of electronically excited Cl2 upon dissociation of phosgene is reported. Evidence for the formation of neutral fragments arising from states embedded in the ionization continuum is discussed.

A method of purification of rare gas halide laser gas mixtures leading to large increases in operational lifetime is reported. Impurity analyses are presented.

Using CW Stimulated Raman Gain Spectroscopy (SRGS), we have measured the temperature dependence of the Raman linewidth in H2 from 298 to 433 K. For a constant density of 10 amagat, we observe an increase in the linewidth of approximately 0.4% per degree K.

We have measuredd phase conjugate reflectivities at 193 nm of 11% using stimulated Brillouin scattering of ArF laser radiation from 2,2,2, ‐Trifluoroethanol (CF3CH2OH). This mirror has been shown to correct for the aberrations induced on the wavefront by an ArF amplifier.

The influence of various chlorine donors, specifically CCl4, Cl2 and HC1, on the formation and decay of the trimer Xe2Cl* has been studied experimentally for electron beam‐excited mixtures of argon, xenon and various halogen donors. Quenching rates of the trimer fluorescence for each donor have been determined. A radiative life‐time for Xe2Cl* of 210±25 ns was measured.

The generation of ultraviolet wavelengths in a regime below that which is easily accessible by conventional doubling techniques in solid state devices - i.e.

The advantages of pulsed excimer lasers for semiconductor processing are reviewed. Extensive comparisions of the quality of annealilng of ion‐implanted Si obtained with XeCl and ruby lasers have been made. The results indicate that irrespective of the large differences in the optical properties of Si and UV and visible wave‐lengths, the efficienccy of usage of the incident energy for annealing is comparable for the two lasers. However, because of the excellent optical beam quality, the XeCl lasser can provide superior control of the surface melting and the resulting junction depth. Furthermore, the concentrations of electrically active point defects in the XeCl laser annealed region are 2−3 orders of magnitude lower than that obtained from ruby or Nd:YAG lasers. All these results seem to suggest that XeCl lasers should be suitable for fabricating not only solar cells but also the more advanced device structures required for VLSI or VHSIC applications.

XeF(Xv''), produced by KrF laser photodissociation of XeF2, is dye laser pumped to XeF(Bv') and XeF(Cv') permitting for the first time the observation of absorption spectra for the C←X transition. The vibrational analysis of the C−X bands locates the C(v’=0) level to lie 775 cm−1 below the B(v’=0) level, and yields the first experimental vibrational constants for the C state. A bandshape analysis of the C−X bands suggests that the equilibrium internuclear separation of the C state lies around 2.48 A. Vibrational relaxation and vibrationally resolved collision‐induced dissociation of XeF(Xv'') is observed.

We have used exploding metal films and wires to optically pump the 342‐nm I2 laser. Specific output energies as high as 18 joules/liter and electrical efficiencies up to 0.27% have been measured. Several parametric studies have been conducted.

We provide experimental evidence to show that the onset of constriction of the active discharge region is the major cause of premature pulse termination in a long pulse duration (270 ns FWHM), resistively ballasted, XeCl* laser. The observation that the discharge invariably becomes more unstable against constriction as the partial pressure of the electron attaching component (HC1) in the gas mixture is increased is contrary to the predictions previously published theories of instabilities in RGH laser discharges. These theories cannot be reconciled with the experimental results presented here because they do not take explicit account of the intrinsically spatial nature of the constriction mechanism.

The B−X, C−X, and D−X transitions of HgCl, HgBr, and HgI are reanalyzed using Tesla discharge sources containing single isotopic species of these molecules. Direct, simultaneous least‐squares fits of all transitions yield optimal vibrational constants for all four states. Low‐resolution studies of the emission as a function of buffer gas pressure show effects of vibrational relaxation in the B state and collisional quenching of the C and D states. The broad B−A bands in the red and infrared are weak but clearly present, in support of a recent report of this transition in HgBr. In addition there is evidence of other transitions, previously unreported for these molecules, including a very weak system near 2200 A in HgI, which shows fine red‐degraded vibrational band structure.

Discharge characteristics and output performance of a self‐sustained discharge XeCl laser have been investigated exxperimentally and theoretically. The operating E/P and discharge resistivity in a quasi‐steady state were studied with Ne‐ and He‐based mixtures; E is the electric field strength and P the operating pressure. Electron energy distribution functions of these mixture became almost equal at each E/P. Small absorption and faster gain build‐up due to faster ion‐ion recombination resulted in more efficient energy extraction in Ne‐based mixture. Moreover, our theoretical model predicted the further scaling limitation not due to the build‐up of nonsaturable absorption but due to the consumption of HC1.

Harmonic generation was studied using a high powered, ultrashort pulse KrF excimer laser. Third, fifth, and seventh harmonic outputs were observed at 82.8 nm, 49.7 nm, and 35.5 nm. The nonlinear interaction took place at the interaction of thee laser focus with a pulsed, supersonic gas jet expansion.

Because of their UV wavelengths and high average powers, excimer lasers can be used in a variety of processing applications for microelectronics fabrication. These new applications are based on using the laser light to control or initiate chemical reactions at a gas solid interface. This paper will review a series of such applications.

Two‐ and three‐body quenching and formation constants for electron beam‐excited XeF(B,C) and Xe2F have been measured. XeF(C) is identified as the precursor of the triatomic rare gas excimer Xe2F which radiation around 64 nm with a spectral bandwidth of 125 nm.

The generation of highly ionized iodine (3+), xenon (5+) and mercury (4+) atoms at pressures of ∼10−6 Torr and laser intensities of ∼1014 W/cm2 at 193 nm is described. A minimum energy in excess of 170 eV, corresponding to ≥ 27 photons, is required to produce Xe5+.

The first observation of third‐harmonic conversion of XeF laser radiation is reported. Xe was found to be a suitable converting medium, with conversion dominated by effects related to three photon resonant enhancement.

The use of a laser amplifier as a Degenerate Four‐Wave Mixing (DFWM) element for phase conjugation is a powerful general technique, particularly useful for UV excimer lasers. In this paper we will discuss our initial experiments, which yielded the first demonstration of DFWM in a XeCl amplifier.

Frequency tripling a doubled dye laser in a pulsed argon source has produced ∼1010 photons/pulse, permitting excitation of H2 between 973 and 1023 A.

Stimulated emission in molecular hydrogen, on both the Lyman and Werner bands excited by two quantum absorption at 193 nm, has resulted in the generation of radiation as short as 117.6 nm at an efficiency of conversion approaching one percent.

An optical approach to monitoring the population densities of the rare gas dimer ions Xe+2 and Kr+2 in real time has been developed. An excimer laser is used to photodissociate the Rg+2 ion via the 1(1/2)u→2(1/2)g UV absorption band and the resulting depletion of the molecular ion population is detected by observing the 6p→6s fluorescence of the neutral xenon or krypton atom. This technique has been applied to examining the formation kinetics of the triatomic rare gas‐halide molecule Xe2Cl (2Γ).

The evolution of thin liquid silicon films has been directly observed in a time resolved picosecond laser melting experiment. Liquid layers up to 100nm thick were formed on crystalline substrates with 15 picosecond 248nm pulses from a KrF* excimer laser. The film thickness as a function of time was probed directly by observing attention of 1.64μm 15psec light pulses transmitted through the melt. Thermo‐dynamics of rapid phase transitions can be studied using this technique.