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We evaluate a new transmission grating spectrometer for standoff laser-induced breakdown spectroscopy (LIBS) measurements. LIBS spectra collected from standoff distances are often weak, with smaller peaks blending into the background and noise. Scattered light inside the spectrometer can also contribute to poor signal-to-background and signal-to-noise ratios for smaller emission peaks. Further, collecting standoff spectra can be difficult because most spectrometers are designed for laboratory environments and not for measurements in the field. To address these issues, a custom-designed small, lightweight transmission grating spectrometer with no moving parts was built that is well suited for standoff LIBS field measurements. The performance of the spectrometer was quantified through 10 m standoff LIBS measurements collected from aluminum alloy samples and measurements from spectra of a Hg--Ar lamp. The measurements were compared to those collected using a Czerny--Turner reflective grating spectrometer that covered a similar spectral range and used the same ICCD camera. Measurements using the transmission grating spectrometer had a 363% improved signal-to-noise ratio when measured using the 669nm aluminum emission peak. [c] 2010 Optical Society of America OCIS codes: 050.0050, 120.6200, 230.1950, 280.3420, 300.6365.

An active spectrophotopolarimeter sensor and support system were developed for a military/civilian defense feasibility study concerning the identification and standoff detection of biological aerosols. Plumes of warfare agent surrogates [gamma]-irradiated Bacillus subtilis and chicken egg white albumen (analytes), Arizona road dust (terrestrial interferent), water mist (atmospheric interferent), and talcum powders (experiment controls) were dispersed inside windowless chambers and interrogated by multiple C[O.sub.2] laser beams spanning 9.1-12.0 [micro]m wavelengths (2). Molecular vibration and vibration-rotation activities by the subject analyte are fundamentally strong within this 'fingerprint' middle infrared spectral region. Distinct polarization-modulations of incident irradiance and backscatter radiance of tuned beams generate the Mueller matrix (M) of subject aerosol. Strings of all 15 normalized elements {[M.sub.ij]([lambda])/[M.sub.11]([lambda])}, which completely describe physical and geometric attributes of the aerosol particles, are input fields for training hybrid Kohonen self-organizing map feed-forward artificial neural networks (ANNs). The properly trained and validated ANN model performs pattern recognition and type-classification tasks via internal mappings. A typical ANN that mathematically clusters analyte, interferent, and control aerosols with nil overlap of species is illustrated, including sensitivity analysis of performance. [c] 2010 Optical Society of America OCIS codes: 070.5010, 120.5050, 120.6710, 280.1415, 290.1350.

The first demonstration to our knowledge in the spectral range from 300 to 1100 nm is presented for the amplitude modulation characteristics of a two-channel 648-pixel liquid crystal spatial light modulator. The broadest spectral amplitude modulation for UV (380-420 nm) and visible-to-near-IR (500-900 nm) pulses to generate a spectral-shifted pulse pair is experimentally realized. The results show that the liquid crystal spatial light modulator has a potential application for attosecond extreme-UV pulse characterization with the conventional SPIDER algorithm and the capability to shape monocycle optical pulses. [c] 2010 Optical Society of America OCIS codes: 230.6120, 320.5540, 320.7100, 320.7160.

The labeled form of dipeptide H-Pro-Trp-OH was subjected to spectral analysis. The structure was found to be composed of a stretched conformer with an extended backbone and a folded conformer with hydrogen bond based on an Infra red-UV analysis.

The aggregates of polycyclic aromatic hydrocarbons like coronene are analyzed by vibrational spectroscopy and also for their thermodynamic properties. The vibrational spectra of aggregates show deviation from the normal modes of vibrations and the cluster capacity of 300 molecules is required for detection of the melting point.

An application of the practical, simple, and reliable approach for the determination of the absolute configuration of sterically demanding tert/tert vic-diols is described. The sign of CD bands occurring at around 310, 350, and 400 nm, it was possible to establish the chirality of the diol unit expressed by the sign of the O-C-C-O torsion angle.

A novel experimental procedure to measure the near-surface distribution of atmospheric trace gases by using passive multiaxis differential absorption optical spectroscopy (MAX-DOAS) is proposed. The procedure consists of pointing the receiving telescope of the spectrometer to nonreflecting surfaces or to bright targets placed at known distances from the measuring device, which are illuminated by sunlight. We show that the partial trace gas absorptions between the top of the atmosphere and the target can be easily removed from the measured total absorption. Thus it is possible to derive the average concentration of trace gases such as N[O.su.b2], HCHO, S[O.su.b2], [H.su.b2]O, Glyoxal, BrO, and others along the line of sight between the instrument and the target similar to the well-known long-path DOAS observations (but with much less expense). If tomographic arrangements are used, even two- or three-dimensional trace gas distributions can be retrieved. The basic assumptions of the proposed method are confirmed by test measurements taken across the city of Heidelberg. OCIS codes: 010.1290, 280.1120, 300.1030.

Near-infrared (~0.7 to ~2.5 [micro]m) spectra of S-asteroids 138 Tolosa, 306 Unitas, 346 Hermentaria, and 480 Hansa suggest the presence of variable amounts of orthopyroxene [+ or -] clinopyroxene [+ or -] olivine [+ or -] plagioclase feldspar on the surfaces of these asteroids. The spectra of these asteroids were compared to laboratory mineral mixtures of orthopyroxene, clinopyroxene, and olivine [Singer, R.B., 1981. J. Geophys. Res. 86 (B9), 7967-7982; Cloutis, E.A., 1985. Master's thesis]. The band parameters (band centers, band areas) were quantified and temperature-corrected [Moroz et al., 2000. Icarus 147, 79-93; Gaffey et al., 2002. In: Bottke Jr., W.F., Cellino, A., Paolicchi, P., Binzel, R.P. (Eds.), Asteroids III. The University of Arizona Press, Tucson, pp. 183-204]. Each S-asteroid in this paper exhibits an overall spectral shape with band parameters that are inconsistent with ordinary chondrite near-infrared spectra and their inferred mineral abundances and/or pyroxene chemistries. 138 Tolosa displays a complex spectrum with a broad ~1 [micro]m absorption feature that displays a double Band I minimum, a well-defined absorption at ~1.3 [micro]m, and a broad, but weak absorption in the ~2 [micro]m region. Although different interpretations exist, the Tolosa spectrum is most consistent with a ~60/40 mixture of Type B clinopyroxene and orthopyroxene. Spectra of 306 Unitas suggest a surface with variable amounts of low-Ca pyroxene and olivine. Unitas is located in the S-(IV) and S-(VI) subtype regions in Gaffey et al. [1993. Icarus 106, 573-602]. 346 Hermentaria exhibits a complex, broad Band I absorption feature and a weak Band II feature, which suggests a ~50/50 mixture of clinopyroxene and orthopyroxene. Hermentaria is classified as an S-(III). Spectra of 480 Hansa suggest a dominant low-Ca pyroxene component with lesser amounts of olivine. Based on these characterizations, these four S-asteroids should not be considered as potential ordinary chondrite parent bodies. Furthermore, these results suggest that these S-asteroids experienced at least partial melting temperatures [T [greater than or equal to] ~950 [degrees]C: Gaffey et al., 1993. Icarus 106, 573-602; Keil, K., 2000. Planet. Space Sci. 48,887-903] during the formation epoch in the early Solar System. Continuing spectroscopic investigations will discern the relative abundance of chondritic and thermally-evolved objects among the S-type asteroids that have survived since the formation epoch ~4.56 billion years ago. Keywords: Asteroids, composition; Mineralogy; Spectroscopy; Thermal histories

We present the results of a visible spectroscopic survey of 820 asteroids carried on between November 1996 and September 2001 at the 1.52 m telescope at ESO (La Silla). The instrumental set-up allowed an useful spectral range of about 4900 A < [lambda] < 9200 A. The global spatial distribution of the observed asteroids covers quite well all the region between 2.2 and 3.3 AU though some concentrations are apparent. These are due to the fact that several sub-sets of asteroids, such as families and groups, have been selected and studied during the development of the survey. The observed asteroids have been classified using the Tholen and the Bus taxonomies which, in general, agree quite well. Keywords: Asteroids; Asteroids, composition; Spectroscopy: Surfaces, asteroids

A spectroscopy chemical investigation of proton-coupled electron transfer is flavodoxin D- vulgaris hildenborough (Fld) is reported. The slow deprotonation step has a benefit to prevent undesirable loss of reducing the equivalents resulting from semiquinone oxidation to quinone.

The surface structures and segregation of ultrathin polystyrene (PS)

A photoinduced effect on the rate of reverse inter system crossing in single sulforhodamine molecules were studied using a novel two-color, multipurpose, double resonance technique. Results from single color, pulsed experiments showed no evidence of photoindused reverse for two dyes DiI and SRIoI.

Matrix isolation spectroscopy is used to examine the oxidation of methyl(phenyl)silyene. The formation of a dioxasilirane is considered to occur from the cyclization reaction and is presented.

Issues concerning the study of conformationally ordered oligomers in solution for the development of a binding site for guest molecules are discussed. Use of induced circular dichroism spectroscopy reveals the reaction of an achiral oligomer with a chiral molecule indicating that binding occurs within the hydrophobic tubular cavity of the oligomer helix.

Issues concerning the use of nonlinear vibrational spectroscopy to measure the adsorption of docosanethiol from ethanol solution onto polycrystalline gold are reported.

Issues concerning the comparison of the spectra and thermal properties of a crystal and an annealed polymer particle are presented.

Issues concerning the effects of a partial Au monolayer on the kinetics of water formation and adsorption on a stepped Pt(335) surface are presented.

Issues concerning the use of single-crystal cw-ESR spectroscopy to study pure organic ferrimagnets are presented. The classical picture of ferrimagnetic spin state is not adequate for describing organic molecule-based exchange-coupled spin systems.

Issues concerning the use of the spin-probe 5-doxyl stearic acid to reveal the mechanism of formation of the hexagonal mesoporous material MCM-41 are reported.

The article discusses the study of optically detected magnetic resonance to determine the presence of dichroic components.

The article discusses research into the use of ultrafast spectroscopy to study the subpisecond ring opening of chemical 7-dehydrocholestrol.

Hydrogen bonding is significant in biology i aqueous surrounds and in atmospheric processes. Molecular complexes of ring molecules with argon and water with supersonic jet millimeter-wave absorption spectroscopy, have been successfully investigated. The technique has also been applied to the study of the complex of water with pyrrolidine, a ring amine. The axial conformer was observed in the rotational spectrum of isolated PRL, although a small mua dipole moment component could have stopped the observation of the rotational spectrum of the equatorial conformer.

The oscillation spectrum of a diode-pumped Nd:YVO4 laser with frequency-shifted feedback (FSF) reveal a longitudinal mode structure that is chirped across the oscillation bandwidth. The FSF laser sustains a continuous chirp. The RF spectrum of homodyne-detected signal shows two components, namely the continuously changing and static frequency, with variation in the path difference.

A noninvasive transcutaneous method developed for measuring small vibrations on a local area of the heart wall is capable of measuring vibrations up to 1 kHz in a water tank. However, the range decreases to 100 Hz for the signals of the interventricular septum in in vivo experiments. The consideration of phase and amplitude of the demodulated signal of the heart wall vibration allow an accurate determination of vibration velocity. The technique gives better resolution in the ultrasonic spectra than the conventional motion-mode echocardiography.

Chromium doped forsterite crystals having a high Cr4+ concentration show a large absorption coefficient of 3.2 per cm at the fundamental wavelength of Nd:YAG laser. The laser output characteristics from three output mirrors having different transmissions give the internal round-trip loss. The study of absorption, fluorescence and lasing characteristics show output energy of 1.2 mJ and 25% slope efficiency. This is highest value obtained in case of pulse operation.

The spectral chlorophyll-specific absorption coefficients of phytoplanktonic populations at mesotrophic and oligotrophic sites in the tropical North Atlantic show vertical and site-specific variations. The oligotrophic site has the largest vertical variability, while it is lower for the mesotrophic site. The presence of non-photosynthetic carotenoids explains the observed variation in the fluorescence yield. A huge depression in the blue part of the spectrum suggests spectral selectivity. The chromatic adaptation by phytoplanktons to spectral irradiance is discussed.

Circular dichroism spectroscopy and thermal denaturation experiments show that distamycin A binding destabilizes a triple-helix but stabilizes a double-helix. Distamycin A, a minor groove binding drug, binds to a triple-stranded form of a single oligonucleotide. This highly stable triple-helix is formed by the oligonucleotide by folding back on itself twice. Spectral analysis shows that the triple-helix bound distamycin has a conformation similar to the double-helix bound distamycin. Distamycin dissociates the triplex made of unbridged chains to give a double-helix.

The reactions of monoacyl- and bisacylphosphine oxides that act as photoinitiators for radical polymerization are analyzed using ESR spectroscopy and 31P-nuclear magnetic resonance-chemically induced dynamic nuclear polarization (CIDNP). A modified Kaptein's rule interprets the 13C and 1H spectra by accounting for the large hyperfine coupling constant of the 31P-nucleus. The analysis shows that the carbonyl-phosphinoyl bond photolysis in the oxides occurs from a triplet state. The removal of intermediates by trapping agents and the fate of primary radicals is discussed.

The presence of red chirp in the spectrum of actively mode-locked semiconductor lasers (AML's) and blue chirp in passively mode-locked lasers (PML's) produces a difference in their chirp characteristics. The change in refractive index with carrier density produces a linear chirp, and that with electron temperature produces a small non-linear chirp in AML's. The change in refractive index with carrier density and electron temperature produce linear chirps in PML's. Stable operation of the lasers depends on the laser's spectrum and external cavity.

A (1 + 1) Schiff base condensation between tris(2-aminoethyl)amine (tren) and a tripodal trialdehyde leads to a macrobicyclic heteroditopic cryptand. In the cryptand structure, the rigidity of the donor atoms imposes a distorted geometry on the Cu(II) ion. Incorporation of the Cu(II) ion in the cavity of the tren end leads to a trigonal-pyramidal conformation for the Cu(II) ion. The Cu(II) ion also bonds with the anions CN-, SCN- and N(super -)(sub 3). Spectral analysis predicts the crystal structures of (Cu(L)(CN))(picrate) and (Cu(L)(NCS))(picrate).

The Ru(bpy)(CN)(super 2-)(sub 4) complex, where bpy = 2,2'-bipyridine, and the (32)ane-N8H(super 8+)(sub 8) polyaza macrocycle combine to form a supercomplex in water and acetonitrile. Formation of the supercomplex in acetonitrile leads to significant changes in the redox and spectral behaviors. Considerable changes are observed in the photophysics and spectral signals of the supercomplex in both the solvents. In the supercomplex, four cyanide ligands are attached to the macrocycle in a boat conformation.

Stereospecific addition reaction between dication (M2S2O2)2+ and the divacant gamma-(SiW10O36)8- in the presence of dimethylformamide produces the Keggin oxothio heteropolyanions, gamma-(SiW10M2S2O38)6- (M = Mo(V), W(V)). A gamma-isomer of the polyanion Keggin structure, NEt4Cs3H2(SiW10Mo2S2O38).6H2O, has a C(sub 2v) geometry with metal-metal bonding. The two MO3S2 units of the isomer are attached via a S-S bonding. Spectrum analysis shows that NEt4Cs5(SiW12S2O38).7H2O is isostructural to the gamma-isomer.

Electron-nuclear double resonance (ENDOR), at 95 GHz, was used to characterize the (super 57)Fe(III) sites in zeolites. Hyperfine couplings between -29.0 MHz and -29.6 MHz are typical of (super 57)Fe(III) in a zeolite framework. The W-band signals are devoid of second- and third-order hyperfine and zero-field splitting interactions and are easily resolvable. The zero-field splitting interactions resulted in a random broadening of the X-band ENDOR spectra for (super 57)FeL, (super 57)FeMFI, and (super 57)FeMAz.

The complexation between a tripodal, potentially heptadentate ligand, tris(2-(N-(2-pyridylmethyl)amino)ethyl)bishexafluorophosphate (TPAA), and manganese ion can yield a seven-coordinated Mn(II)-TPAA complex. X-ray crystal structural analysis indicates that three pyridine nitrogen atoms, three amine groups, and the tripodal bridging nitrogen comprise the seven coordinating links with Mn(II). Spectroscopic, electrochemical, and gamma and pulse radiolysis confirm the reaction of the Mn complex with superoxide. The IC50 value of the compound is 4.4 micromolar, based on a cytochrome C assay.

The reaction of 5,6-diamino-1,10-phenanthroline with ((bpy)M(phendione)) produces monometallic ((bpy)2Ru(tpphz))(super 2+) and ((bpy)2Os(tppz))(super 2+) (tppz = tetrapyrido- (3,2-a:2',3'-c:3'',2''-h:2''',3'''-j)phenazine) complexes. Proton NMR analysis indicates that both the complexes aggregate in solution through the pi-pi stacking of tppz. The complexes exhibit luminescence in acetonitrile. Mononuclear complexes show a strong MLCT band at 400-500 nanometer due to the overlap of M(II) with bpy(pi*) and M(II) with tppz(pi*) orbitals.

The lowest energy electronic transition of Re(X)(CO)3(alpha-diimine) (X = Cl, Br, I; alpha-diimine = bpy, iPr-PyCa, iPr-DAB) changes from Re to alpha-diimine (MLCT) to X to alpha-diimine (XLCT) on moving from Cl to Br. Resonance Raman spectra and time-resolved absorption and emission spectroscopy show that the change in excited state is attributed to an irregular mixing of the d(sub pi)(Re) and p(sub pi)(X) orbitals. The emission from the XLCT excited state exhibits a longer lifetime due to the slow nonradiative decomposition to the ground state.

Iron-57 Mossbauer spectroscopic and ac susceptibility measurements of the magnetic characteristics of (NH4)2FeF5.H2O reveal transitions to a three dimensional magnetic ground state at nearly 2.2 K. The magnetic phase of Mossbauer spectra is accompanied by a nearly 50% relaxation fraction. The limiting internal hyperfine filed is 45 T. The relaxation fraction is absent in K+, Rb+ and Cs+ compounds. The depletion of the magnetic equivalence of Fe3+ is attributed to the structural phase transition.

Global warming is positively correlated with global carbon dioxide emission. Cross-spectral and multichannel spectra analyses are used to analyze the Granger causal relationship. Causality analysis confirms the existence of Granger causality between global surface temperature and CO2 emission. The frequency domain analysis reveals that global warming is attributed to an increase in carbon dioxide emission. The increase in CO2 concentration increases global temperature and causes climatic changes.

Thousands of hectares of forests are burned annually in wildfires and prescribed burns nationwide. Our objective was to determine the effects of such fires on soil phyrosilicates. At five sites throughout California representing Inceptisols, Andisols, and Mollisols, surface soil samples from similar depths were collected in burned and nearby unburned areas. Fires produced no visible soil alterations except in 1 to 2% of the land area where concentrated fuel such as logs or stumps burned slowly and at higher temperatures, effectively baking the underlying soil. Within the upper 1 to 8 cm at these severely burned areas, kaolin was completely destroyed or substantially depleted and [d.sub.001] spacings of clay-sized vermiculite, chlorite, chlorite-vermiculite, and hydroxy-interlayered verinicutite collapsed toward 1.0 nm or were decomposed as shown by x-ray diffraction. Dehydroxylation of severely burned Fe-bearing phybosilicates was indicated by Mossbauer spectroscopy. The decomposition of virtually all phyllosilicates in the upper 2 cm of the soil was observed at one site after burning. The effects of severe burning on the soil phyllosilicates remained clearly expressed at least 3 yr after a fire.

Analysis of the internal mobility of the protein eglin c using spectral density functions of the NH vectors indicates dynamic heterogeneity along the backbone of the protein at lower spectral density values. The spectral-mapping technique is useful in evaluation the spectral density functions, J(sub omega), at five frequencies. The 15N-1H measurements of 15N-enriched eglin c are discussed.