Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
  • 11
    Electronic Resource
    Electronic Resource
    Room-temperature optical nonlinearities in strained (InAs)2(GaAs)5 superlattice quantum wells (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 3243-3248 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report room-temperature measurements of the nonlinear absorption cross section, σeh, and the nonlinear refraction coefficient, neh, associated with saturation of excitonic absorption and bandfilling, for high-quality multiple quantum well (MQW) structures in which each well consists of a highly strained, all binary (InAs)2(GaAs)5 short-period superlattice. The three samples studied, which have effective well thicknesses of 10.7, 14.8, and 18.8 nm, respectively, each display clearly resolved excitonic resonances at room temperature. Picosecond nonlinear transmission and transient grating measurements were performed on each sample in the spectral vicinity of the n = 1 heavy-hole excitonic resonance. The peak values of neh and σeh extracted from these measurements are comparable to those measured in high-quality GaAs/AlGaAs and unstrained InGaAs/InP MQWs. We determine the dependence of σeh and neh on the width of the quantum wells, and we discuss the fluence dependence of the nonlinearities. Consistency between the differential transmission and transient grating diffraction efficiency is demonstrated via a Kramers–Kronig analysis of the differential transmission spectra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348544
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 12
    Electronic Resource
    Electronic Resource
    Picosecond optical nonlinearities in a strained InAs/GaAs hetero n-i-p-i structure (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 929-932 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The nonlinear optical properties of a n-i-p-i structure containing strained superlattice quantum wells in the intrinsic regions are studied using picosecond pump and probe pulses of the same photon energy. For pump fluences as low as 1.1 μJ/cm2, a blue shift of the excitonic resonance, caused by the screening of the built-in space-charge field and the accompanying reduction in the quantum-confined Stark effect, is clearly observed. At higher fluences, the onset of bleaching of the excitonic absorption is observed. The nonlinearities associated with the quantum confined Stark effect in the hetero n-i-p-i are directly compared to those arising from excitonic bleaching in identical strained superlattice quantum wells under flatband conditions. The picosecond time resolution allows a more accurate estimation of the carrier density in the hetero n-i-p-i by ignoring the density-dependent recombination and a quantitative comparison between the strength of the nonlinearities in the two structures. Although such comparisons depend on the optical fluence and structure of the hetero n-i-p-i, we find that the magnitudes of the nonlinearities in these two specific structures are comparable on a per carrier basis, although their spectral signatures are quite distinct.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351315
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    Optical nonlinearities and ultrafast charge transport in all-binary InAs/GaAs strained hetero n-i-p-i's (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6891-6897 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We use picosecond differential spectroscopy to temporally and spectrally resolve the formation and decay of nonlinearities and space-charge fields in a hetero n-i-p-i that contains quantum wells in the intrinsic regions that are composed of all-binary InAs/GaAs short-period strained-layer superlattices. The evolution of the optical response is determined by competition between excitonic bleaching and the excitonic shift caused by screening of the built-in electric field of the n-i-p-i. The relative contributions of the two resulting optical nonlinearities are complicated functions of fluence, time, and wavelength, with the detailed dynamics determined by thermionic emission from the wells, picosecond charge transport over nanometer dimensions, screening, and recombination. At low fluences, excitonic bleaching is the source of an ultrafast nonlinear response that can be turned on and off in 〈10 ps. This initial excitonic bleaching gives way to a blue shift of the exciton as the carriers escape the wells in ∼3 ps and drift to screen the built-in field in 〈10 ps. The blue shift persists until the carriers recombine nonexponentially on microsecond time scales. At higher fluences, excitonic bleaching and the blue shift are observed simultaneously, since only a fraction of the carriers are required to screen the field and the wells remain partially occupied. On the time scale of ∼10 ns, the bleaching contribution disappears as the carriers within the wells recombine, leaving only the persistent blue shift.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349813
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 14
    Electronic Resource
    Electronic Resource
    Close-coupling optical model analysis: A refined optical potential surface for He*(2 1S)+H2 (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 240-245 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A complex-arithmetic version of Johnson's log–derivative integration method has enabled a straightforward extension of the close-coupling approximation to complex-potential surfaces. The complex-potential close-coupling (CPCC) method is applied to the determination from our earlier scattering measurements of an improved anisotropic optical potential for the He*(2 1S)+H2 Penning ionization system, with the aid of a new, nonpiecewise potential surface function based on the improved Tang–Toennies model. The potential is compared to earlier ab initio results, and the CPCC method is used to assess the shortcomings of the complex-infinite-order-sudden (CIOS) approximation. Variation of differential and ionization cross sections with the initial rotational state of H2 predicted by CPCC may be experimentally observable, and may also provide an explanation for the observed H2/D2 isotope effect in quenching rates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.455511
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 15
    Electronic Resource
    Electronic Resource
    Collision energy dependence of Penning ionization electron spectra in crossed supersonic beams: He*(2 1S)+N2 (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 5347-5348 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Penning ionization electron spectra are reported at five collision energies E in the range 1.6–4.9 kcal/mol. A preliminary analysis of the E dependence of the intensities, shapes, and positions of the vibronic lines reveals details of the ionization dynamics, features of the highly anisotropic potential surface, and connections with N2 orbital structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459655
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 16
    Electronic Resource
    Electronic Resource
    Collision energy dependence of product branching in Penning ionization: He*(2 1S, 2 3S) + H2, D2, and HD (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 1564-1576 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Relative ionization cross sections for the title systems with articulation of all product ion channels have been measured in the collision energy range 1.5–4.0 kcal/mol using crossed supersonic molecular beams; the H2 results have been extended down to 0.5 kcal/mol by the use of a 10% H2/Ar seeded beam. The data are interpreted with a microscopic two-step model that assumes ionization near the turning point in the excited state, a centrifugal barrier criterion for ionic complex formation, and statistical partitioning of flux among the possible ionic products, i.e., phase-space theory. A full statistical calculation underestimates the amount of rearrangement ionization He*+H2→HeH++H+e− by a factor of 2, but one which excludes antiparallel coupling of orbital and rotational angular momenta in the H+2 channel is in better accord with the data. A substantial isotope effect favoring HeD+ over HeH+ in the HD reactions by a factor of 1.9±0.2 is well represented by the model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456049
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 17
    Electronic Resource
    Electronic Resource
    Observation of propagating collective excitations in liquid SO2 (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 5387-5391 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The spectrum of collective excitations in liquid sulphur dioxide at two thermodynamic states has been measured by neutron triple-axis spectroscopy for momentum transfer ranges of 0.35≤Q≤2.0 A(ring)−1. Well-resolved inelastic peaks indicating the presence of propagating modes are found for Q values below 0.5 A(ring)−1 at T=266 K and below 0.7 A(ring)−1 at T=210 K. A precise value for the hydrodynamic limit has been found in both cases and the measured "dispersion relations'' are discussed in relation to predictions made by recent theoretical approaches.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.461654
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 18
    Electronic Resource
    Electronic Resource
    Multichannel analysis of He*(21S)+Ne elastic and inelastic scattering in crossed atomic beams (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 5963-5974 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: State-to-state elastic and inelastic angular distribution and time-of-flight measurements are reported for the scattering of He*(21S) by Ne in crossed supersonic atom beams at four collision energies in the range 0.6–2.8 kcal/mol. The inelastic collision products He+Ne*(nl), where nl=3d', 4p, 4p', 5s, 5s', and 4d, are scattered predominantly forward with respect to the direction of incidence, except for endothermic states near threshold. The data are analyzed with a numerically exact multichannel curve-crossing model that yields good agreement with experimental cross section branching fractions and total quenching and state-to-state rate constants as well as the angular measurements. The model suggests the importance of intermediate "chaperone'' states, in which the excited electron is temporarily trapped in a d or f Rydberg Ne orbital, in channeling flux into the 4s' and 5s' upper laser states of Ne by energy transfer from He*(2s1,3S).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458367
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 19
    Electronic Resource
    Electronic Resource
    Reflection absorption infrared spectroscopy at the Daresbury SRS : Proceedings of the 4th international conference on synchrotron radiation instrumentation (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 1547-1550 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The high brilliance of modern synchrotron radiation sources results in a significant intensity advantage over conventional sources in the far infrared region of the spectrum. For applications with inherently low étendue, such as reflection absorption infrared spectroscopy (RAIRS) of surfaces, this advantage extends into the mid-infrared (IR) region, to 1000 cm−1 or higher. The spectroscopic region between 100 and 1000 cm−1 is of particular interest in surface science since it includes the vibrational modes of the majority of direct bonds between the surface and adsorbate, but the low intensity of conventional sources renders investigations of this region difficult. In this paper, we discuss the design criteria of the new Daresbury infrared beamline.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143807
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 20
    Electronic Resource
    Electronic Resource
    New similarity reductions of the Boussinesq equation (1989)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 30 (1989), S. 2201-2213 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: Some new similarity reductions of the Boussinesq equation, which arises in several physical applications including shallow water waves and also is of considerable mathematical interest because it is a soliton equation solvable by inverse scattering, are presented. These new similarity reductions, including some new reductions to the first, second, and fourth Painlevé equations, cannot be obtained using the standard Lie group method for finding group-invariant solutions of partial differential equations; they are determined using a new and direct method that involves no group theoretical techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.528613
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...