It is known that high molecular weight, thermally labile molecules can be desorbed intact using keV ion beams. This knowledge has led to numerous applications of fast atom bombardment (FAB) and secondary ion mass spectrometry (SIMS) by mass spectrometric detection of the desorbed ions. Here we show that these measurements can be significantly enhanced by using resonance enhanced laser ionization to softly ionize the neutral component of the desorbed flux. This experimental configuration can produce sensitivity improvements of several orders of magnitude over SIMS while adding a certain degree of selectivity to the ionization process itself. Examples of this performance will be presented using a wide variety of molecules including aromatic hydrocarbons, a number of biologically relevant compounds and organic polymer substrates. In some cases, detection limits in the attomole range can be achieved.

Resonant and nonresonant laser ionization of sputtered neutral atoms are compared for silver/gold alloys and silica/silicon wafer implants. The results obtained from these two different ionization schemes represent complementary information on the sputtered species. There are chemical and photofragmentation effects that must be considered for quantitative determinations of the surface and sub-surface species. Both ionization schemes are necessary to obtain complete information on the sample.

Resonance ionization mass spectrometry (RIMS) of neutral atoms sputtered from semiconductors is used to provide quantitative information about the major and minor constituents. If the photoionization process is demonstrated to be saturated, RIMS signals can be related to the absolute concentrations of many elements in semiconductors such as Si and GaAs. RIMS signals are demonstrated to be nearly element-independent, that is, equal concentrations of impurities such as Be, Al, and Co in Si give equivalent signals. However, partitioning into various quantum states and velocities of sputtered atoms must be considered when comparing interelement signals on an absolute basis. Three- photon ionization is shown to be useful in reducing some background ionization effects and detecting high ionization potential non-metal elements.

Resonance Ionization Spectroscopy (RIS), an analytical technique with extremely high element specificity and sensitivity, is becoming recognized as an emerging field with wide applications. The sensitivity and selectivity of the RIS process is especially valuable for ultra-trace element analysis in semiconductor, geological, biological, and environmental samples, where the complexity of the matrix is frequently a serious source of interference. Using either Sputter-Initiated RIS (SIRIS) or Laser Atomization RIS (LARIS), it is possible to localize with high spatial resolution ultra-trace concentrations of a selected element to the sub-parts per billion level. The authors describe the implementation of RIS to solve a number of analysis problems and illustrate its salient characteristic with data from a wide range of applications. Results presented will include (a) concentration plots of ultra- trace elements in semiconductors and biological matrices, (b) characterization of dopants as a function of depth in semiconductors, (c) spatial distribution of natural uranium in bone and bone marrow, and (d) localization of stable isotope-labeled DNA in the development of faster DNA sequencing methods. The practical capabilities of SIRIS/LARIS to determine trace elements as a function of depth and lateral position in semiconductors and biological matrices are discussed.

Spectroscopic methods tend to exhibit an inverse correlation between sensitivity and the ability to discriminate between similar structures. Were they obtainable with adequate sensitivity, magnetic resonance spectra could resolve structural controversies involving the nature of clusters, ions, semiconductor defects and catalytic intermediates. This paper describes several novel approaches to magnetic resonance, which have in common that the spins are coupled to other degrees of freedom in order to obtain nonequilibrium polarization and/or greater detection sensitivity. The methods under development include single-ion electron spin resonance (ESR) detected by ion trapping frequencies, catalyst NMR detected by the branching ratio to different spin symmetry species, and semiconductor nuclear magnetic resonance (NMR) detected via the circular polarization of luminescence.

Laser spectroscopy has become a widely used popular technique in analytical chemistry during the laser decade. Numerous studies have documented the results of the advantages of lasers (low detection limits, for example); however, most of the applications have focused on the use of relatively expensive lasers. Much less effort has been directed toward the development of analytical methods using semiconductor lasers. With the development of semiconductor lasers a new approach to laser enhanced analytical methods has become possible. Semiconductor lasers are a source of monochromatic, tunable coherent beams of light, characteristic of other types of lasers, with the additional benefit of compactness. At the present time semiconductor lasers are available only for the red and the near-infrared (NIR) region of the spectrum, a situation that required the development of new methods for giving analytically useful signals in the NIR spectral region. The shortwave NIR region of the spectrum is advantageous due to its relatively low interference. Fluorescence spectroscopy is an inherently sensitive technique; however, the analysis of complicated biological samples may require the simultaneous acquisition of absorption spectra. In this regard absorption measurement involves the use of multiple spectroscopic parameters to increase the specificity of the measurement. Laser diodes are excellent light sources for both absorption and fluorescence spectroscopy. Low detection limits may be achieved using the intracavity method for absorption measurements. Moreover, laser intracavity spectroscopy has an important advantage when implemented with laser diodes: the built-in integral monitoring photodiode (PIN) can be used as a detector. The advantages and disadvantages of different methods of laser diode control are discussed in this paper, as are several different analytical applications. Simultaneous fluorescence detection is also possible with an additional detector. Superior detection limits may be achieved using NIR laser diode excited fluorescence spectroscopy. In this paper the use of NIR laser diode spectroscopy in analytical chemistry is demonstrated.

Theoretical and practical limits for detection of trace concentrations of gas phase species using frequency modulation spectroscopy are described. A variety of frequency modulation schemes are examined, including wavelength modulation (harmonic detection) spectroscopy (WMS) and one-tone and two-tone frequency modulation spectroscopy (FMS). The distinctions among these methods are mostly semantic and all of these techniques can be described by a single theory. The goal of this research is to define guidelines useful for implementing the optimum modulation technique for specific measurement needs. Applying this formalism, expected sensitivities for each method are compared for selected absorption systems. The results suggest that the choice among techniques is most strongly driven by the individual laser tuning characteristics, the absorption linewidth and the detection bandwidth; no individual method is a priori superior. Results of experimental diode laser measurements which confirm these calculations are presented. Predicted minimum detectable concentrations for a representative variety of gas phase species are also shown.

The authors explore analytical applications of remote Raman spectroscopy using fiber optics. In these applications, emphasis is placed on the use of portable near-infrared excitation sources, including diode and diode-pumped lasers, for the purpose of developing a truly portable instrument. This paper addresses the instrumentation that is being developed for this purpose, including the portable Raman spectrometer and some fiber-optic probe designs.

Spectroscopy of ions in electromagnetic traps using laser-cooling and detection has reached a sensitivity where it is now possible to unambiguously monitor state changes in a single ion. While these techniques may not be generally applicable, the sensitivity and precision that is obtained for laser-cooled ions give broad opportunities for experiments in many areas of fundamental physics and-high resolution spectroscopy. In this paper, the authors describe two experiments with a single laser-cooled Hg+ ion. In one they achieve the highest fractional resolution (highest Q) in atomic or molecular spectroscopy, and in the second they cool the ion to its zero-point energy.

Progress is reported on the development of a new laser- and mass spectrometer- based technique for measurement of trace levels of radioisotopes. Significant results to date include the demonstration of high efficiency and throughput in a mass spectrometer, efficient production of metastable atoms from Ar+ and Kr+ beams, a demonstration of the photon burst detector principle with Mg+ ions, and the verification of zero background in a two- detector system.

Laser spectroscopy based on degenerate four-wave mixing (D4WM) has been demonstrated to offer excellent spectral resolution since the signal is inherently Doppler free. When using a low-pressure demountable discharge cell, Lorentzian (pressure) broadening is also minimized. In addition to excellent spectral resolution, this nonlinear laser method also offers excellent detection sensitivity for gas-phase samples. The authors demonstrate that this nonlinear laser method can be used also as a highly sensitive analytical method to detect trace amounts of analyte in the condensed phase using continuously flowing liquid cells at room temperature. Both pulsed lasers and relatively low-power continuous-wave lasers can be used to generate the signal. Since the signal is detected against virtually a dark background and the signal beam is a time-reversed replica of the probe laser beam, optical signal can be most efficiently collected. Condensed phase D4WM detection sensitivity is comparable or better than those of laser-based fluorescence methods and yet D4WM is applicable for detection of both fluorescing and non- fluorescing molecules. Therefore, room-temperature degenerate four-wave mixing has many applications in analytical chemistry, especially when interfaced to continuously flowing chemical separation methods including liquid chromatography and capillary electrophoresis.

Subwavelength light sources have been constructed with the aid of luminescent and exciton transporting materials. These EXCITOR (exciton transmitted optical radiation) sources produce evanescent luminescence and can be used as scanning, light emitting tips of nanometer dimensions. They can also be used as scanning exciton donor tips. The theoretical resolution limit of this kind of near-field optical microscopy is on the atomic or molecular scale. The detection limit is a single molecule, but in contrast to other single molecule detection methods, this single molecule could be identified spatially as well as spectrally. Experimental examples of such an EXCITOR tip consist of gold or aluminum coated glass micropipettes with active crystal tips (anthracene, tetracene, perylene, etc.). Design considerations involve optical, excitonic, photochemical and mechanical properties of the luminescent point source. As it is scanned over a sample, it senses a variety of perturbations such as quenching or external heavy atom effects. It can also actively excite a luminescent probe. The latter process can be non-radiative (e.g., Forster) or may involve absorption and re-emission of evanescent luminescence. Spatially coupled emission and absorption processes are of both theoretical and practical interest. They open a way for reducing by many orders of magnitude the number of photons required to excite a single, isolated chromophore. Molecular exiton microscopy allows extention of near-field microscopy beyond the 50 nm limit already achieved and, thus, permits a new frontier of resolution with light based on the limits of energy transfer measurements. In essence, then, the goal of this research is a spectrally sensitive light microscope that will have the capability to zoom non-destructively and in air from the limits of resolution of lens-based confocal light microscopy (200 nm) to molecular dimensions of 1 nm.

Thermal lens spectroscopy (TLS) has demonstrated the ability to make sensitive measurements at the trace level and absorbance detectabilities approaching 2 X 10-7 cm-1 are possible. With proper experimental design it has recently been demonstrated that this same detectability can be achieved with TLS even in the presence of a background signal which is several orders- of-magnitude larger. The basis for this capability is a pump/probe differential thermal lens spectrometer which can effectively minimize the influence of the background signal on the photothermal measurement. The key experimental parameters will be described which allow sensitive measurements to be made under such limiting conditions. The system will be applied to the development of an indirect photothermal detection scheme for microcolumn HPLC and to the photothermal detection of circular dichroism.

Photothermal spectroscopy has emerged as a popular spectroscopic technique over the past decade because it is convenient and sensitive. It is convenient since a wide range of samples of all phases from highly opaque, light- scattering or reflective to highly transparent materials can be measured to some level of accuracy over a broad spectral range with little or no sample preparation. It is sensitive since, in principle, it is a 'zero background' technique, unlike the tradition extinction technique to measure absorption. However, in practice, various sources of noises become significant when the absorption approaches the part-per-million level or below, and various considerations of noise suppression and signal enhancement are essential to exploit photothermal spectroscopy, in particular, photoacoustic spectroscopy and probe-beam deflection spectroscopy. The authors consider here the physical basis for signal generation and enhancement, as well as noise sources and reduction schemes for pulsed and continuous-modulated excitations. Examples of experimental techniques are given to illustrate the points

The refractive index gradient (RIG) of hydrodynamically controlled profiles can be universally, yet sensitively, measured by carefully probing the radial RIG passing through a z-configuration flow cell. Fiber optic technology is applied in order to provide a narrow, collimated probe beam (100 micrometers diameter) that is deflected by a RIG and measured by a position sensitive detector. The fiber optic construction allows one to probe very small volumes (1 (mu) L to 3 (mu) L) amenable to microbore liquid chromatography ((mu) LC). The combination of (mu) LC and RIG detection is very useful for the analysis of trace quantities (ng injected amounts) of chemical species that are generally difficult to measure, i.e., species that are not amenable to absorbance detection or related techniques. Furthermore, the RIG detector is compatible with conventional mobile phase gradient and thermal gradient (mu) LC, unlike traditional RI detectors. A description of the RIG detector coupled with (mu) LC for the analysis of complex polymer samples is reported. Also, exploration into using the RIG detector for supercritical fluid chromatography is addressed.

Measurements of time-resolved fluorescence are increasingly used for research in biophysics, biochemistry, cell biology and medicine. Advances in the technology of light sources and detectors are resulting in more reliable and/or advanced instrumentation, which is resulting in the expanding applications of fluorescence spectroscopy. Time-resolved measurements are often performed by direct measurements in the time-domain. In this article the authors describe the alternative method of frequency-domain fluorometry. The frequency-response of the emission to intensity-modulated excitation can be used to recover the time-dependent decay. Commercial instrumentation now allows measurements to an upper light modulation frequency limit of 200 MHz. This laboratory has developed second and third generation instruments which allows measurements to 2 GHz and subsequently to 10 GHz. The frequency-domain data from such instrumentation provides excellent resolution of picosecond decays of intensity and anisotropy. Additionally, the frequency-domain method appears to provide remarkable resolution of complex decays which are often observed for biochemical samples. In this article the authors describe this instrumentation and applications of this method. Examples are shown using probes with ps decay and correlation times, the intrinsic fluorescence of proteins, and the measurement of end-to-end diffusion in proteins and/or flexible molecules.

Low zeptomole (1 zmol equals 10-21 mol = 600 molecules) detection limits are produced for DNA sequencing by capillary gel electrophoresis. A 750 (mu) w green helium-neon laser ((lambda) equals 543.5 nm) is used to excite tetramethylrhodamine-labeled DNA fragments in a sheath-flow cuvette. A cooled photomultiplier tube is used to detect fluorescence in a single spectral channel. Sequencing data is generated at a rate of about 70 bases/hour.

Sequencing the human genome is a major undertaking considering the large number of nucleotides present in the genome and the slow methods currently available to perform the task. The authors have recently reported on a scheme to sequence DNA rapidly using a non-gel based technique. The concept is based upon the incorporation of fluorescently labeled nucleotides into a strand of DNA, isolation and manipulation of a labeled DNA fragment and the detection of single nucleotides using ultra-sensitive laser-induced fluorescence detection following their cleavage from the fragment. Detection of individual fluorophores in the liquid phase was accomplished with time-gated detection following pulsed-laser excitation. The photon bursts from individual rhodamine 6G (R6G) molecules travelling through a laser beam have been observed, as have bursts from single fluorescently modified nucleotides. Using two different biotinylated nucleotides as a model system for fluorescently labeled nucleotides, the authors have observed synthesis of the complementary copy of M13 bacteriophage. Work with fluorescently labeled nucleotides is underway. Individual molecules of DNA attached to a microbead have been observed and manipulated with an epifluorescence microscope.

Single molecules of DNA can be visualized in solution by epifluorescence microscopy, manipulated and extended by a variety of mechanical, electrical and chemical means as described previously. This has been used to design experiments under an optical microscope, in which DNA molecules are extended by a known force, to determine the elastic response of the molecules, both in the presence and absence of ethidium bromide. It is found that at lower forces (smaller extensions) the molecules behave as entropic springs with a persistence length of 500 angstroms, and that at the ionic strengths used, the intercalation of ethidium bromide does not alter this persistence length, while it appears to elongate the contour length of the molecule by about 30%.

Trace elements are important for many essential metabolic functions. Zinc is a structural/functional component in more than 200 enzymes active in the biochemistry of cell division and tissue growth, neurology and endocrine control. Calcium is involved in intracellular control mechanisms and in skeletal bone building and resorption processes related to osteoporosis. Sensitive and selective laser photoionization is being developed to understand mechanisms in smaller samples and biological units approaching the cellular domain. Zinc has an ionization potential of 9.4 eV, or 75766.8 cm-1. Several processes are being explored, including two-photon resonant, three- photon ionization utilizing sequential UV transitions, e.g., 4s2 1S0 yields 4s4p 3P1 and 4s4p 3P1 yields 4s5d 3D1. Preliminary zinc stable isotope ratio data obtained by thermal atomization and laser photoionization agree with accepted values within 2 to 5%, except for anomalous 67Zn. Photoionization of calcium is being studied for isotope enrichment and ratio measurement using narrow and medium bandwidth lasers. Several ionization pathways, e.g., 4s2 1S0 - 2hv1 yields 4s10s - hv2 yields Ca+ (4s2S), are being investigated for isotopically selective ionization. Auto-ionization pathways are explored for greater efficiency in isotopic analysis. All studies have utilized a Nd:YAG- pumped laser system with one or two frequency-doubled tunable dye lasers coupled either to a magnetic sector or time-of-flight mass spectrometer.

An overview is given of advanced analytical techniques and instrumentation, such as surface-enhanced Raman scattering (SERS) and antibody-based fiber- optic sensors, used to detect trace levels of chemical pollutants and related biomarkers in complex environmental samples.

A laser spectroscopic technique known as 'fluorescence line narrowing spectroscopy' (FLNS) provides an unprecedented level of detail in the study of cellular macromolecular damage to DNA due to chemical reactions in vitro and in vivo with organic carcinogens. The reactions are believed to be the first step in the induction of tumors. Different stereoisomers of the metabolite benzo[a]pyrene diol epoxide (BPDE) which binds to DNA bases and the same stereoisomers in different DNA site configurations can be directly distinguished. By comparing BPDE adducts formed from synthetic polynucleotides of specific base composition, insights into the nature of BPDE-DNA adduct structure types can be obtained. It is shown that FLNS can be used to study metabolic pathways and DNA damage routes from benzo[a]pyrene and 7,12- dimethylbenzanthracene. BPDE-human hemoglobin adducts can also be identified. Due to its high sensitivity and superior selectivity, FLNS could be the basis for a practical and reliable body burden assessment methodology.

Development of the electrodynamic balance with laser light-scattering capabilities has made it possible to perform a wide variety of measurements on solid particles and liquid droplets with sizes ranging from about 0.1 to 200 micrometers and masses in the range 10-15-10-5 g. An introduction to the principles and design of electrodynamic balances is provided, and recent advances in their application to the measurement of optical properties, chemical composition and chemical reaction rates via elastic and inelastic scattering from microparticles are reviewed. Of particular emphasis are the phenomena of morphological or structural resonances, which can be used to determine optical properties of dielectric spheres with very high precision, and Raman and fluorescence spectroscopies, which provide information on the chemical nature of the microparticle. It is demonstrated that elastic and inelastic scattering measurements on levitated microdroplets can be used to measure chemical composition changes of multicomponent droplets. It is also shown that the complex refractive index of weakly absorbing droplets can be determined by measuring their evaporation rates via optical resonance spectra. The major problem associated with the interpretation of Raman spectra for microparticles is examined, and that is the effect of morphological resonances on the Raman emission. Data on the enhancement of Raman signals by such resonances are presented.

Single-absorber optical spectroscopy in solids may be regarded as the problem of finding a single dopant impurity molecule in a 'haystack' composed of 1012 - 1018 background host molecules and up to $OM106 additional impurity molecules. Detailed studies of the low-temperature inhomogeneously broadened 0-0 S1 $IMP S0 electronic transition of pentacene dopant molecules in p-terphenyl crystals have yielded both (1) observations of spectral structure scaling as N, where N is the number of impurity molecules in resonance, and (2) the optical absorption spectrum of a single impurity molecule in a solid (N equals 1). Recent advances in fluorescence excitation of very small volumes have greatly improved the signal-to-noise ratio for a single molecule.

We present a new method for isolating optically active rare earth ions embedded in a crystalline or amorphous host. The technique relies upon the enhanced site selection created by an inhomogeneously broadened line in a sufficiently dilute system. Specific spatial and frequency requirements necessary for experimental observation of such systems are discussed. Preliminary data is presented demonstrating the technique. With additional experimental measures, detecting a single rare earth ion appears feasible.

Small clusters of atoms and molecules formed by supersonic expansion are found in a given experiment at different levels of aggregation and in multiple isomeric forms. The spectra of such aggregates nucleated by aromatic molecules can be analyzed in detail through the use of hole-burning spectroscopy. The present approach employs two pulsed dye lasers at approximately 1 cm-1 resolution, separated in time by 120 ns. Through detailed analysis of vibrational mode structure, the evolution of the spectroscopic properties of probe molecules can be followed as a function of cluster size and structure. Particular points of interest include the development of low-frequency modes due to intermolecular motion and the perturbation of out-of-plane modes of the aromatic host species. The application of picosecond time-correlated single- photon counting to the transfer of vibrational energy in small clusters, and some structural changes initiated by such transfer, is also described.

A precolumn derivatization method has been developed for high performance liquid chromatographic (HPLC) analysis of DNA damage using fluorescence detection. The modified nucleotide, having excised enzymatically from the exposed DNA, is enriched from the normal nucleotides and labeled with a fluorescent reagent. The labeling procedure involves phosphoramidation of the nucleotide with ethylenediamine (EDA) followed by conjugation of the free amino end of the phosphoramidate with 5-dimethylaminonaphthalene 1-sulfonyl chloride, commonly known as Dansyl chloride. The dansylated nucleotide can be analyzed with a sub-picomole limit of detection (LOD) by conventional HPLC using a conventional fluorescence detector. By combining microbore HPLC with laser-induced fluorescence (LIF) detection, we present the development of an analytical system that has sub-femtomole LOD for real-time analysis of the dansylated nucleotide. The application of the developed system in fluorescence postlabeling assay of a small alkyl-modified nucleotide (5-methyldCMP) in calf-thymus DNA is discussed.

The demand to measure high dynamic range isotope ratios on small samples with resonance ionization mass spectrometry (RIMS) continues to increase. This paper discusses high ionization efficiency methods which can be applied to continuous wave (cw) RIMS to potentially achieve several tens of percent ionization efficiencies for certain elements. The primary technique under development to achieve this is an external laser cavity which can generate very high circulating laser powers.

A novel electronic circuit has been developed that detects absorption in one of two (reference and signal) laser beams with shot noise-limited sensitivity. The authors demonstrate its use as a simple shot noise limited spectroscopy by measuring several absorption lines of I2 vapor near 670 nm with a tunable diode laser. The noise-equivalent absorption in this double-beam method is 2 times the shot-noise-to-signal ratio of the signal beam. In this case, for 1.2 mW of power, the noise-equivalent absorption in a 1-Hz bandwidth was 4.2 X 10-8. This noise level was confirmed, although measurements were sometimes limited by interference fringes and laser tuning drift. These are technical, not fundamental, problems arising from unsophisticated optical equipment. This baseband method provides absorption spectra directly, eliminating laser excess noise without the somewhat elaborate signal generation and processing equipment needed in laser frequency modulation methods. The only modulation used in the system was the 0.5 to 1.0-kHz sweep of the diode laser current used to tune the laser output wavelength. The noise-cancelling circuit itself is not complex: workable versions can be constructed from readily available components at a cost of about 10 dollars.

In a high J-value scheme (photo-excitation sequence), the authors investigate the characteristics of three-step photo-ionization, through an autoionizing level, of a complex atom using three single-mode pulsed dye lasers. The report covers (1) ion yield dependence on the balance of three laser intensities; (2) AC Stark effect, observed in intermediate excitation; and (3) multi-photon-resonance effect in a stepwise near-resonant excitation. The experimental results are discussed through comparison with the theoretical analyses, that include the effects of magnetic sublevel degeneracy.

The authors report on obtaining generation of a CO2 laser with a phase- anisotropy three-mirror cavity operating in a linear orthogonal polarized double-mode regime. Power and frequency characteristics of a double-mode three-mirror laser are also studied. It was proved that in a double mode CO2 laser with an internal absorbing cell the saturation of the absorbing medium can be significantly reduced with the help of a three-mirror telescopic cavity. Narrow nonlinear resonances of high amplitude were obtained in a CO2/SF6 laser with the help of phase-anysotropy three-mirror telescopic cavity.

Several key elements important for the application of laser-based photothermal spectroscopies to the study of the complexation chemistry of lanthanides and actinides in solution have been demonstrated. The sensitivity of f-f electronic transition energies and band intensities to subtle changes in complexation is illustrated through comparison of visible and near infra-red absorption spectra of well-characterized U(IV) dimers with alkoxide ligands. Significant improvements in spectroscopic band resolution and energy measurement precision for solution species are shown to be achievable through work in frozen glasses at 77 K using a very simple cryogenic apparatus. A pulsed-laser photothermal spectroscopy apparatus was constructed and shown to be sensitive to optical density changes of 10-5 in an aqueous Nd3+ solution. In addition, the capability of obtaining photothermal lensing spectra of dilute actinide solutions in frozen glasses at 77 K is demonstrated.

The Water Window Imaging X-Ray Microscope is currently being developed by a consortium from the Marshall Space Flight Center, the University of Alabama at Birmingham, Baker Consulting, the Lawrence Livermore National Laboratory, and Stanford University. The high quality solar images achieved during the Stanford/MSFC/LLNL Rocket X-Ray Spectroheliograph flight conclusively established that excellent imaging could be obtained with doubly reflecting multilayer optical systems. Theoretical studies carried out as part of the MSFC X-Ray Microscope Program demonstrated that high quality, high resolution multilayer x-ray imaging microscopes could be achieved with spherical optics in the Schwarzschild configuration and with Aspherical optical systems. Advanced Flow Polishing methods have been used to fabricate substrates for multilayer optics. On Hemlite grade Sapphire, the authors have achieved microscope mirror substrates on concave and convex spherical surfaces with 0.5 A rms surface smoothness, as measured by the Zygo profilometer. In this paper the current status of fabrication and testing of the optical and mechanical subsystems for the Water Window Imaging X-Ray Microscope is reported.

Silicon nitride (Si3N4) has been demonstrated to be an effective high- temperature anti-oxidant, especially when deposited in its (alpha) -crystalline form. UTRC has developed a pilot scale chemical vapor deposition (CVD) reactor capable of depositing (alpha) -Si3N4 from ammonia (NH3) and silicon tetrafluoride (SiF4) at 1450 C. Coherent anti-Stokes Raman spectroscopy (CARS) has been applied to this reactor which has been fitted with line-of- sight optical access ports. Temperature and concentration measurements have been performed on gas phase species during the deposition of Si3N4. Based on the CARS detection of H2, the importance of high temperature surface (Si3N4) catalyzed decomposition of NH3: 2NH3(Delta )yields3H2 + N2, is established as a competing reaction to: 4NH3 + 3SiF4(Delta) )yieldsSi3N4 + 12HF, in the CVD reactor under deposition conditions. Mass spectroscopic measurements, performed on the reactor exhaust, confirm that the primary gas phase species are N2, H2 and HF. H2 is observed spectroscopically both in the presence and absence of SiF4, and in a variety of precursor composition ratios.

Silicon nitride (Si3N4) has been demonstrated to be an effective high temperature anti-oxidant, especially when deposited in its -ciysta1line form. UTRC has developed a pilot scale chemical vapor deposition (CVD) reactor capable of depositing cv-Si3N4 from ammonia (NH3) and silicon tetrafluoride (SiF4) at 1450 C. Coherent anti-Stokes Raman spectroscopy (CARS) has been applied to this reactor which has been fitted with line-of-sight optical access ports. Temperature and concentration measurements have been performed on gas phase species during the deposition of Si3N4. Based on the CARS detection of H2, the importance of high temperature surface (SiN4) catalyzed decomposition of NH3:

There are a great attention to charge exchange proceses investigation in MIS (Metal-Insulator--Semiconductor) structure under strong field conditions last years because of creating a new generations of optoelectronic and microelectronic devices in silicon technology.The matrix type MIS avalanche pulsed spectro-photometer with spatial resolution ( Matrix-Pulsed-Spectro-Photometer) and the new type of Color Video Camera [1) could be such an examples working in a hot electrons injection ( from Si to 5102 regime.A lot of experiments have been performed to study this effect.To our viewpoint, Ning's experimental setup is the most interesting allowing to measure the absolute emission probability of electrons which were optically generated in the silicon depletion layer and accelerated toward the Si-Si02 interface [2).But in these experiments the substrate voltage range was restricted by 19V value that far below the avalanche process conditions in MISAPs (3]. It is the purpose of this paper to present a new experimental technique for emission probability investigation in MIS structure under avalanche conditions based on pulsed avalanche multiplication parameters extraction [3).This technique is a part of the complex experimental metod (41 for charge exchange investigation ( hot carriers transport in Si, generation-recombination processes in Si-Si02 interface, injection of hot carriers from Si into Si02, trapping and detrapping phenomena in Si02) in Avalanche-MIS-Structure (MISAS).