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Diagnostic near‐infrared spectral features have been identified for minerals with ammonium [Formula: see text] bound in the crystal structure. Spectral bands near 2.12, 2.02, and 1.56 μm are characteristic of synthetic and natural [Formula: see text] minerals. Laboratory spectra of [Formula: see text] minerals are distinct from spectra of OH‐bearing minerals and have diagnostic shifts in band position among different mineral types. [Formula: see text] minerals were detected at several mineralized hot‐spring deposits in the western U.S. by means of hand‐held and airborne instruments. Near‐infrared detection of [Formula: see text] minerals may provide useful information for prospecting for certain ore deposits and may provide a better understanding of the nitrogen cycle within geologic environments.

Systematic experiments have shown that saturation density, nucleation rate, and condensation coefficient are considerably smaller than previously reported. The low condensation coefficient and the linear deposition rate dependence of the nucleation rate show that the model usually applied for the theoretical explanation of the nucleation process needs some revision. From measured condensation coefficients we have estimated the diffusion length of adatoms, xs = (14.4 j = 2.4) nm, and the difference between desorption and diffusion energy, E , -E,, = (0.31 f 0.01) eV. Possible reasons for the deviation of the new results from the earlier ones are discussed.Systematische Experimente haben gezeigt, daB die Siittigungskeimdichte, die Keimbildungsrate und der Kondensationskoeffizient wesentlich niedriger sind als fruher veroffentlichte Werte. Der geringe Kondensationskoeffizient und die lineare Abhiingigkeit der Keimbildungsrate von der Aufdampfrate weisen darauf hin, da13 das Modell, das gewohnlich zur theoretischen Beschreibung des Keimbildungsvorgangs verwendet wird, einiger Veriinderungen bedarf. Aus den gemessenen Kondensationskoeffizienten konnte die Diffusionslange der Adatome bei 150"C, x8 = (14,4 f 2,4) nm, und die Differenz zwischen Desorptionsund Diffusionsenergie, E, -E,, = (0.31 & 0,Ol) eV, abgeschiitzt werden. MoglicheUrsachen fur die Unterschiede zwischen den neuen und den fruheren Ergebnissen werden diskutiert.

Examination of SEASAT SAR images of eastern Maryland and Virginia reveals botanical distinctions between vegetated lowland areas and adjacent upland areas. Radar returns from the lowland areas can be either brighter or darker than returns from the upland forests. Scattering models and scatterometer measurements predict an increase of 6 dB in backscatter from vegetation over standing water. This agrees with the SCWigital number (DN) increase observed in the digital SEASAT data. The brightest areas in the Chickahominy, Virginia, drainage, containing P. virginica about 0.4 m high, contrast with the brightest areas in the Blackwater, Maryland, marshes, which contain mature loblolly pine in standing water. The darkest vegetated area in the Chickahominy drainage contains a forest of Nyssa aquatica (water tupelo) about 18 m high, while the darkest vegetated area in the Blackwater marshes contains the marsh plant Spartina alterniflora, 0.3 m high. The density, morphology, and relative geometry of the lowland vegetation with respect to standing water can all affect the strength of the return L band signal.

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