ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

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
  • 1
    Electronic Resource
    Electronic Resource
    A theoretical study of I2 vibrational motion after excitation with an ultrashort pulse (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 5693-5699 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We calculate the population created by a short pump pulse exciting the I2 molecule to the bound region of the B state, followed by excitation with a short probe pulse to the state E (or F). The nuclear state produced by the pump oscillates in the well of the B state and the probe is absorbed to populate the E (or F) state only when the wave function passes through the Franck–Condon region of the B→E (or B→F) transition. Because of this, the population on the E (or F) state oscillates with the delay time between the pump and the probe. The calculations agree with the experiment in the case when the probe excites the E state. When the F state is excited the theory predicts a doublet structure which is not observed; moreover, in some cases the experiment and theory differ at the shortest delay times. We discuss the dependence of the LIF signal on the pulse width and the initial state, the long time behavior of the LIF signal, and illustrate the role of the population transients on the B states at early times, during or immediately after the pump pulse acted on the molecule.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459563
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Excitation of symmetric and asymmetric stretch in a symmetric triatomic molecule: A time-dependent (collinear) analysis of the IHI− photodetachment spectrum (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 16-22 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We present time-dependent quantum calculations for the collinear IHI−→IHI transition, which has been studied before by time-independent methods by Schatz [J. Chem. Phys. 90, 4847 (1990)] and Bowman and Gazdy [J. Phys. Chem. 93, 5129 (1989)]. The mass ratio of the atoms involved determines the time scales of the symmetric stretch on the one hand and the asymmetric stretch on the other. Both modes are excited in the transition complex. We demonstrate how resonances in the spectrum can be related to the motion of the ionic wave function on a potential energy surface for IHI. The dynamical picture is complementary to the one which is obtained from the stationary state calculations. The system under consideration differs in many aspects from other examples of symmetric triatomic molecules. The dynamics corresponding to structures in the spectrum reveals the peculiarities of heavy–light–heavy systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460391
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    CH3ONO predissociation by ultrashort laser pulses: Population transients and product state distribution (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 2317-2327 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We use a two-dimensional potential energy surface for CH3ONO to model the behavior of the molecule interacting with an ultrashort laser pulse. All the results presented here are obtained by solving accurately the time-dependent Schrödinger equation; when possible we also develop a simple model to explain the exact observations. We calculate the lifetimes of the predissociative resonances, the transient populations induced by semi-infinite pulses, and the time evolution of the product state distribution after excitation with a very short pulse. The behavior of the excited state population created by the pulse is explained in terms of the interference between the amplitudes representing photon absorption at different times when the pulse–molecule interaction is not zero. The time evolution of the final state distribution is explained in terms of interference between the wave packets at different times from the interaction region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.457973
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    A time-dependent interpretation of the absorption spectrum of CH3ONO (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 1-13 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We use time-dependent quantum theory to interpret the absorption spectrum of CH3ONO in terms of the nuclear motion on the upper potential surface. The model uses one excited potential energy surface and two nuclear coordinates: the NO stretch and the CH3O–NO bond. The latter bond breaks upon excitation leading to dissociation. The spectrum consists of a broad band and two progressions corresponding to predissociation resonances. The band width is inverse proportional to the time scale on which the NO bond length increases to adjust to the longer equilibrium bond length of the upper potential energy surface. The progression of intense narrow resonances corresponds to the NO stretching motion. The other progression is due to oscillations along the reaction coordinate of the wave function temporarily trapped in the predissociation well. Our calculations show that important dynamic information can be obtained by "smearing off'' the high resolution spectrum to generate a series of low resolution versions which reveal the time scales on which various spectral features develop in the spectrum. We also show that time-dependent theory can be used efficiently to calculate the lifetime of relatively long lived resonances.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458463
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Periodic orbits and diffuse structures in the photodissociation of symmetric triatomic molecules (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 3252-3257 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We reinvestigate the collinear photodissociation of a symmetric triatomic molecule studied a decade ago by Kulander and Light [J. Chem. Phys. 73, 4437 (1980)], within the time-dependent formalism. The diffuse structures in the absorption spectrum are uniquely related to three, well separated recurrences which, in turn, are explained by three generic periodic orbits of the corresponding classical Hamiltonian. One of these orbits describes pure symmetric stretch motion while the other two orbits combine symmetric stretch and hyperspherical motion. The applicability of simple one-dimensional, zeroth-order pictures is reviewed in the light of these new results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458858
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Interference effects in the photodissociation of FNO (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 1040-1048 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Two-dimensional wave packet calculations on the photodissociation of FNO→F+NO in the S1 state were carried out to analyze the asymmetric resonance line shapes (Fano profiles) in the absorption spectrum in terms of a continuum, a resonance, and an interference contribution. Vibrationally resolved partial cross sections were calculated which predict a strong variation of the vibrational state distribution in the NO fragment as a function of the energy in the vicinity of a resonance. This effect is due to a substantial interference contribution to the vibronic absorption cross section. The results were compared to recent experimental findings by Reisler and co-workers and to the Fano model applied to predissociation. Further, we simulated the excitation with a semi-infinite laser pulse to extract resonance energies from the time behavior of the calculated S1←S0 transition rates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.466687
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Mapping of wave-packet dynamics in a double-well potential via femtosecond pump/probe photoelectron spectroscopy (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 2673-2677 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The kinetic energy distribution of electrons obtained from femtosecond pump/probe ionization of Na2 is calculated. The pump laser pulse prepares a vibrational wave packet in the 1Σ+u double minimum potential of the molecule which serves as the initial state for subsequent ionization induced by absorption of another photon from the probe pulse. The time dependence of the electron kinetic energy distribution reflects details of the vibrational dynamics. In particular the splitting of the packet can be observed in the case when its mean energy equals the barrier height between the potential wells. The estimate of several molecular properties from a theoretical analysis of the electron spectra is carried through and discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.467647
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Two-photon wave-packet interferometry (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 5448-5458 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The excitation of a molecule by a short pulse creates a wave packet whose motion depends on the nuclear forces of the excited electronic state. The properties of such a packet can be studied interferometrically. This is done by exposing the molecule to two identical pulses delayed from each other. Two packets are thus created and the excited state population has a term which depends on the interference between them. This interference population is a quantum effect and its dependence on the delay time reflects the coherence properties of the packet and is very sensitive to the potential energy surface. In this paper, we examine the use of wave-packet interferometry to study the dynamic properties of packets created by two-photon absorption. We find several interference populations since the packets created by two-photon absorption interfere with each other and with packets created by absorption of one photon from each pulse. The single interference terms contain different physical information and we discuss how each can be measured separately. This method provides a sensitive way for studying the dynamic properties of high energy electronic states that can be reached by two-photon absorption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.467162
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Long time wave packet behavior in a curve-crossing system: The predissociation of NaI (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 7337-7343 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Stimulated by experiments by Zewail and co-workers [Chem. Phys. Lett. 172, 109 (1990)], we perform quantum calculations on the long time behavior of a wave packet which moves on coupled electronic surfaces of the NaI molecule. Beat structures in the simulated femtosecond pump/probe signal are shown to depend critically on the parameters used in the calculation. The adiabatic motion is compared to the dynamics including the nonadiabatic coupling and the consequences for the signal are explored. The results are compared to a semiclassical analysis of Chapman and Child [J. Phys. Chem. 95, 578 (1991)].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.461411
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Effect of transition-metal overlayers on the perpendicular magnetism of MBE-grown, ultra-thin Co films : 37th Annual conference on magnetism and magnetic materials (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 6192-6194 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have used in situ polar Kerr ellipticity measurements to study the perpendicular magnetic behavior of MBE-grown Pd/Co/TM sandwich structures, where TM is the nonmagnetic transition metal overlayer Pd, Cu, or Ag. These structures are epitaxially deposited on thick Pd (111) buffer layers grown on Co-seeded GaAs (110) substrates. Hysteresis curves were measured in situ for systematically varied Co and TM layer thicknesses 2 A(ring)≤tCo≤10 A(ring) and 0 A(ring)≤tTM≤200 A(ring). We observed perpendicular loops with a coercive field of Hc≤200 Oe for the uncovered Co films for tCo≤6 A(ring), becoming in-plane above this thickness. However, subsequent deposition of just one atomic layer (≈2 A(ring)) of any of the TM over the Co resulted in strongly perpendicular, square hysteresis curves with Hc≥700 Oe for all films in the Co thickness range studied. Deposition of TM overlayers causes nonmonotonic behavior in Hc as a function of coverage. We find a peak in Hc at a TM coverage of tTM∼1.5 A(ring) for all materials, with a subsequent monotonic increase above tTM≈4 A(ring) to a limiting value by tTM≈100 A(ring). The peak is most pronounced for Cu, where Hc changes by more than 200%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352694
    Location Call Number Expected 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...