Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 1973-1979 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The ratio of the transverse diffusion coefficient to the mobility, DT/K, has been measured for K+ ions drifting in helium and krypton in the presence of a uniform electric field. Results at 298 K are reported at E/N values ranging from 10 to 220 Td for K+–He and 5 to 420 Td for K+–Kr. Values of DT/K for these two systems were also calculated with a Monte Carlo simulation method which used a number of proposed potentials as input. The accuracy of these potentials has been evaluated by comparing the results to the experimentally determined values. For K+–He none of the available potentials seems to be completely accurate, but for K+ –krypton the potential of Koutselos, Mason, and Viehland appears to be a very good representation of the actual potential. Within the ranges studied, the estimated accuracy of the experimental measurements is ±2.5% and the accuracies for the Monte Carlo calculations are ±1% for K+–He and ±0.5% for K+–Kr.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In the E-157 experiment now being conducted at the Stanford Linear Accelerator Center, a 30 GeV electron beam of 2×1010 electrons in a 0.65-mm-long bunch is propagated through a 1.4-m-long lithium plasma of density up to 2×1014 e−/cm3. The initial beam density is greater than the plasma density, and the head of the bunch expels the plasma electrons leaving behind a uniform ion channel with transverse focusing fields of up to several thousand tesla per meter. The initial transverse beam size with σ=50–100 μm is larger than the matched size of 5 μm resulting in up to three beam envelope oscillations within the plasma. Time integrated optical transition radiation is used to study the transverse beam profile immediately before and after the plasma and to characterize the transverse beam dynamics as a function of plasma density. The head of the bunch deposits energy into plasma wakes, resulting in longitudinal accelerating fields which are witnessed by the tail of the same bunch. A time-resolved Cherenkov imaging system is located in an energy dispersive plane downstream of the plasma. It images the beam onto a streak camera allowing time-resolved measurements of the beam energy spectrum as a function of plasma density. Preliminary experimental data from the first three runs are compared to theory and computer simulations. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Boston, MA, USA : Blackwell Science Inc
    Restoration ecology 10 (2002), S. 0 
    ISSN: 1526-100X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Thin, poorly developed soils in the high elevation, summer-dry environment near Lake Tahoe, California are easily disturbed by anthropogenic impacts. Subsoils and parent materials that are exposed by vegetation removal and topsoil erosion or by burial during construction activities are difficult to revegetate and may continue to erode for decades after disturbance. The resulting sediment loads contribute to decreased water quality in local watersheds and to the loss of clarity in Lake Tahoe. Field observations suggest that soil disturbance often results in depletion of soil nitrogen (N) reserves and that the remaining substrates may be unable to provide adequate N for revegetation. To quantify the levels of soil N that are associated with higher levels of percent plant cover on previously disturbed soils in the Lake Tahoe area, a basin-wide survey and a second paired site study were conducted. Results indicate that extractable ammonium and nitrate levels correlate poorly with percent vegetative cover, whereas the correlations of anaerobically mineralizable N and total N are stronger and account for nearly 50% of the variability in plant cover data. Sites with plant cover measuring greater than 40% are associated with total soil N levels of about 1,200 kg N/ha and anaerobic mineralizable N levels of about 26 kg N/ha. Despite high concentrations of N in the surface soils, a large fraction of the N in the 0- to 50-cm profile occurs below 30 cm, when measured on a landscape basis.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Biochemistry 18 (1979), S. 280-288 
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 1338-1339 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: It has long been known that new alkali ion sources utilizing thermionic emission from alkali aluminosilicates can achieve high percentages of the desired ion by a sufficiently long "burn-in.'' Observations are reported here of instances where increased impurity ion emission can reoccur and lead to possible measurement errors in experimental systems lacking mass spectrometers. The ratio of impurity K+ ions to Na+ ions from a burned-in Na2O⋅Al2O3⋅2SiO2 source was measured to be 0.55.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 3077-3079 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The spinel ceramic material nickel germanate, Ni2GeO4, has been found to exhibit a humidity-dependent impedance. A change in the magnitude of the impedance at 100 Hz, from 108 Ω at 20% RH to 104 Ω at 98% RH, at 298 K, is typical. The effect of frequency on the complex impedance has been investigated over the frequency range 10 mHz–10 MHz, using the technique of impedance spectroscopy. The observed impedance spectra show two regions, indicative of an ionic-charge transport process and a charge transfer to the electrodes, suggesting that at high levels of humidity conduction is essentially electrochemical. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 62 (1991), S. 1047-1053 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new drift-tube apparatus has been developed for measuring DT/K, the ratio of the transverse diffusion coefficient to the mobility of ions in a neutral gas under the influence of an electric field. It harnesses existing technology in mechanical, electronic, materials, and computer engineering. The main features are the ion current detector, which comprises 65 parallel rods, and an external mechanical multiplexer, which was designed to have extremely low (fA order) leakage currents and noise levels. Unlike with other earlier systems, the need for precise mechanical motion or adjustments of experimental conditions inside the drift tube during data collection has been circumvented. Its design therefore simplifies construction and makes operation less error prone. Data collection is computer controlled. A value for DT/K can now typically be obtained in less than 20 min, which greatly increases the rate at which results can be obtained as well as reduces the chance of unwanted variations in experimental conditions occurring during data collection. Results are estimated to be accurate to within 3%.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 586-590 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The ratio, DT/K, of the transverse diffusion coefficient to mobility for Na+ ions drifting in Xe gas has been experimentally measured. Inevitable longitudinal end effects present in the drift tube were duly corrected for. Results at ∼303 K are reported at electric field to neutral gas density ratios, E/N, ranging from 5 to 440 Td. Furthermore, elaborate calculations of the reduced mobility, K0, the ratio, DL/K, of the longitudinal diffusion coefficient to mobility, and DT/K were calculated with a Monte Carlo simulation (MCS) method which used the interaction potential of Koutselos, Mason, and Viehland [J. Chem. Phys. 93, 7125 (1990)] as input. The accuracy of this potential has been evaluated by comparing the results with the experimental data and those calculated using the generalized Einstein relations technique. Agreement within 3% between the experimental values of DT/K and those from MCS calculations for the whole range of E/N suggests that the interaction potential represents fairly well the true potential. The error of the experimental measurements of DT/K is estimated to be better than 3.5% and that of the MCS calculations is better than 1% for K0 and 2.5% for DT,L/K.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Biochemistry 17 (1978), S. 4533-4540 
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Biochemistry 17 (1978), S. 4525-4533 
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...