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  • Analytical Chemistry and Spectroscopy  (12)
  • Basal area  (1)
  • Deserts  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Downward flux of water through roots (i.e. inverse hydraulic lift) in dry Kalahari sands (1998)
    Springer
    Oecologia 115 (1998), S. 460-462 
    Details
    ISSN: 1432-1939
    Keywords: Key words Water transport ; Grass roots ; Hydraulic lift ; Deserts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Downward transport of water in roots, in the following termed “inverse hydraulic lift,” has previously been shown with heat flux techniques. But water flow into deeper soil layers was demonstrated in this study for the first time when investigating several perennial grass species of the Kalahari Desert under field conditions. Deuterium labelling was used to show that water acquired by roots from moist sand in the upper profile was transported through the root system to roots deeper in the profile and released into the dry sand at these depths. Inverse hydraulic lift may serve as an important mechanism to facilitate root growth through the dry soil layers underlaying the upper profile where precipitation penetrates. This may allow roots to reach deep sources of moisture in water-limited ecosystems such as the Kalahari Desert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050541
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  • 2
    Electronic Resource
    Electronic Resource
    Grazing effects upon plant community structure in subhumid grasslands of Argentina (1986)
    Springer
    Plant ecology 67 (1986), S. 27-32 
    Details
    ISSN: 1573-5052
    Keywords: Argentina ; Basal area ; Community structure ; Diversity ; Dynamics ; Flooding pampa ; Grassland ; Grazing effect ; Leaf area
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in plant community structure are identified as a result of grazing in grasslands of the flooding pampa which evolved under supposedly light grazing conditions. The effect of excluding grazing upon total leaf area index was an increase of 30%. The largest response was observed in the distribution of leaves in the canopy. In the grazed areas, most of the green material was concentrated in the 0–5 cm layer while in the ungrazed treatments the largest portion of the leaf area was in the 10–30 cm layer. Grazing exclusion resulted in a small change in total basal area but a larger change in its distribution, from many small tussocks to less numerous large ones. The effect of grazing upon leaf area and basal area was accounted for by changes in vigor as well as by changes in species composition. The major effect of excluding grazing upon species composition was the disappearance of some native planophile species and most of the exotics. The species composition of grazed areas of both communities was very similar while there were large differences between the ungrazed areas and between the grazed and ungrazed areas of the same community. It is suggested that there is a group of species which responds to the coarse-grained ‘signal’ of grazing and its presence can cause dissimilar communities to converge under grazing conditions. The other group of species responded to the fine-grained ‘signal’ of the environmental conditions associated with topography.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00040315
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Vibrational and electronic properties of tris(8-hydroxyquinolinato)vanadium (III) (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 20 (1989), S. 555-560 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A study of the electronic, infrared, Raman and pre-resonace Raman spectra of the solid complex tris(8-hydroxyquinolinato)vanadium(III) was performed. The excitation profiles of the vibrational modes that show preresonance on excitation with laser lines within the electronic bands in the visible region are reported and, on this basis and molecular orbital calculations, several vibrational and electronic absorption bands were assigned.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250200902
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  • 4
    Electronic Resource
    Electronic Resource
    Surface-enhanced Raman scattering of 4-picolylamine and its [Fe(CN)5]n- complexes (1991)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 22 (1991), S. 301-305 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The SER spectra of the complexes [Fe(CN)5(4-picolylamine)]3- and [Fe2(CN)10(4-picolylamine)]6- adsorbed on a silver electrode were investigated. The analysis of the frequency shift of the CN stretching mode indicated that both molecules adsorb via one or more CN ligand groups. For potentials more positive than 0.0 V the CN stretching frequency for both complexes moves towards higher wavenumbers charcterizing the presence of Fe(III) over the surface. The SER spectra of 4-picolylamine adsorbed on a silver electrode in solutions of pH 2.8, 6.5 and 10.3 were also investigated. From the data obtained it was concluded that 4-picolylamine in solution at pH 6.5 and 10.3 adsorbs on the electrode through the nitrogen of the pyridine ring.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250220512
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  • 5
    Electronic Resource
    Electronic Resource
    Raman and infrared spectra and photochemical behaviour of acetaldehyde isolated in matrices (1991)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 22 (1991), S. 505-507 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: As part of a general study on the behaviour of acetaldehyde as an atmospheric pollutant, the Raman and infrared spectra are presented of acetaldehyde isolated in argon and nitrogen matrices. Using the observed frequencies, the thermodynamic functions were calculated. By obtaining the vibrational spectra at low temperature, it was possible to assess the results of the photochemical studies that have been done in matrices with both argon and nitrogen gases. The main products in the photochemical decomposition of acetaldehyde under the conditions adopted are methane and carbon monoxide.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250220906
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Raman spectra of Br3- and I3- adsorbed on zeolites (1981)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 11 (1981), S. 320-321 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Raman spectra of Br3- and I3- adsorbed on several zeolites were investigated in order to verify a previous assignment of bands, observed in the spectra of bromine and iodine adsorbed on zeolites, to the trihalide ions formed in the zeolites.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250110505
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  • 7
    Electronic Resource
    Electronic Resource
    Raman resonance excitation profile of the μ-oxobis[pentacyanomanganate (III)] ion (1987)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 18 (1987), S. 577-579 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The resonance Raman spectra of potassium μ-oxobis[pentacyanomanganate(III)] cyanide, K7[Mn2O(CN)10]CN, were measured using exciting lines at 356.4, 406.7, 530.9, 568.2, 603.5, 647.1 and 676.4 nm. By combining these data with those obtained previously (excitations at 457.9, 476.5, 488.0, 496.5, 514.5 and 608.6 nm), the excitation profiles were plotted for three totally symmetric vibrations at 1880 (CNax strech), 527 (MnCax stretch) and 259 cm-1 (MnOMn stretch). It was found that the equation derived by Mingardi et al. can adequately express these excitation profiles and that the previous assignment of the electronic transition at 509 nm needs revision.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250180808
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Surface-enhanced Raman scattering of the redox pair CO(sep)3+/Co(sep)2+ on silver and copper electrodes (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 20 (1989), S. 725-728 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The surface-enhanced Raman spectra of the redox pair Co(sep)3+/Co(sep)2+ (sep: sepulchrate) adsorbed on silver and copper electrodes have been obtained in the skeletal region for these compounds and the results were consistent with the redox potential of the species. The role of the anions and cations of the support electrolytes in the adsorption of the Co(sep)3+ on a silver electrode suggests that the compound is adsorbed on the electrode via ion pair formation with the anion specifically adsorbed. From the behaviour of the Raman intensity of the CH2 symmetrical stretching vibration it was possible to estimate the pKa of the Co(sep)2+.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250201104
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  • 9
    Electronic Resource
    Electronic Resource
    Polarized Raman spectra of single-crystal barium nitroprusside trihydrate, Ba[Fe(CN)5NO]·3H2OA communication on this subject was presented at the Xth Congress and General Assembly of the IUCr, Bordeaux, France, 19-28 July 1990. (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 23 (1992), S. 131-136 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The room-temperature polarized Raman scattering of single-crystal Ba [Fe(CN)5NO] · 3H2O, space group Pbcm (D112h, No. 57), in the 2200-10 cm-1 spectral range, and a factor group analysis of the nitroprusside anion vibrational modes are presented. The near parallelism between the anion NCFeNO axis and a crystallographic axis facilitates the interpretation of the spectra. The data obtained complement already existing IR studies and the two series of results together provide reference information for the understanding of the vibrational behaviour of the recently reported electronically excited metastable states of the anion. The Raman data confirm the existence of a relatively large correlation (Davydov) splitting between NO stretching modes due to vibrational coupling between neighbouring nitrosyl groups in the lattice.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250230302
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  • 10
    Electronic Resource
    Electronic Resource
    The dependence of Raman intensity on the scattering frequency (1978)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 7 (1978), S. 294-296 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Aqueous solutions of (NH4)2MoS4 have been investigated with Ar+ laser excitation, at frequencies which span the visible absorption spectrum. Enhanced values of the anti-Stokes/Stokes intensity ratios for the fundamental ν1 and overtone 2ν1 show that the Nafie et al. theory accounts satisfactorily for these observed ratios.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250070513
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