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  • 1990-1994  (9)
  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 5646-5655 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We presented a theoretical method for controlling quantum dynamics by locally optimized nonstationary laser fields, within the semiclassical theory of the molecule–radiation field interaction. The external laser field is optimized based on the control theory of a linear time-invariant (LTI) system, so that both the summation of the population of the nontarget states and the total energies of the laser fields are minimized. The optimization procedure involves operation of the so-called feedback gain matrix to the time-dependent state vector. This procedure is carried out at every successive short stage, in which the time-dependent Schrödinger equation can be approximated to the equation of motion of the LTI system. As an example, the control theory was applied to laser-induced ring-puckering isomerization, the dynamics of which can be described as the wave packet in the one-dimensional double minimum potential under locally optimized laser fields. The result indicated that nearly 100% of the population can be transferred to the final product state by irradiation of the optimized laser fields. The optimized laser fields were analyzed to obtain information on the carrier frequencies or the frequency modulation by using the fast Fourier transform method. These results were then compared with the result of isomerization induced by nonoptimized laser fields.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 6586-6592 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We present a theory for controlling the dynamics of a dissipative, quantum system with a laser field optimized locally in time. The theory is applicable to both weak and strong field control of the quantum dynamics. The theoretical groundwork is based on the equation of motion of the density matrix in Liouville space. Interactions between the molecules and the heat bath are taken into account within a Markov approximation. The derivation of the locally optimized laser field in a feedback form is based on the local optimization theory in the Hilbert space, proposed in a previous paper [M. Sugawara and Y. Fujimura, J. Chem. Phys. 100, 5646 (1994)]. The theory is applied to a simple, two-level quantum system with a dephasing constant. We present both the calculated time evolution of the off-diagonal density matrix element and that of the population of the states in the optimized laser field. These calculations show that the control of the system by the laser field is sufficient to avoid the dephasing effects. We discuss how the dephasing dynamics affects the optimization of the laser field.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 4946-4949 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We studied nonradiative recombination centers in undoped (AlxGa1−x)0.5In0.5Pgrown by metalorganic vapor phase epitaxy using transient capacitance spectroscopy. We found three deep energy levels, including a mid-gap level. We drew an equation to get a capture cross section for minority carriers, and obtained it using isothermal capacitance transient spectroscopy measurement. The mid-gap level had an electron capture cross section of 2 × 10−10 cm2 and a hole capture cross section of 1 × 10−15 cm2. The time constant of nonradiative recombination through the mid-gap level was found to be comparable to that of radiative recombination. We concluded that the mid-gap level is an effective nonradiative recombination center that reduces photoluminescence intensity.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of plastic surgery 13 (1990), S. 185-186 
    ISSN: 1435-0130
    Keywords: Rat ; Experiment ; Wounds ; Vinyl chloride vest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A new rat vest for protection of experimental dorsal wounds is described. It can be made easily, can be used repeatedly, is adjustable to the rat's body contours and allows easy observation of the animals. In addition, decubitus ulcers seldom occur.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Heat and mass transfer 26 (1991), S. 225-232 
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Hier ist eine analytische Studie der Schmelzung einer Schneeschicht in einer wässrigen Lösung dokumentiert worden. Ein diffusionsgesteuertes analytisches Modell wurde für die Schmelzung unter idealen Bedingungen vorgeschlagen, um eine wässrige Lösung verzögerungsfrei mit einer Schneeschicht bei gleicher Temperatur wie die Lösung aufzufüllen. Die analytischen Ergebnisse lassen eine gute Voraussage über die experimentellen Ergebnisse der Schmelzung von Schneeschichten zu, die plötlich in einer wasserhaltigen Calcium-Chlorid-Lösung versenkt werden. Die Temperatur des Schmelzsystems fällt sehr schnell während des Schmelzprozesses. Die Schmelzung war in wenigen Sekunden vollendet, dies zeigt ein thermodynamisches Gleichgewicht an. Wenn die AnfangstemperaturT i und die Anfangsdurchlässigkeit ɛ i des Schnees gleich sind, dann ist die AnfangskonzentrationC mi in der Lösung stark durch die beidseitige Erniedrigung der Schmelz-systemtemperatur und der Schmelzmasse pro Einheit VolumenM des Schnees angegriffen. WennC mi undT i gleich sind, dann wird die maximale Schmelzmasse pro Einheit VolumenM max des Schnees nicht sehr vom Schneeteilchendurchmesser angegriffen. Es sind Bilder dargestellt worden, die die Beziehung vonM max−T i,C mi und ɛ aufzeigen. Ebenso wurde eine Relation gezeigt, um die dimensionslose maximale SchmelzmasseM max * leicht vorherzusagen.
    Notes: Abstract An analytical study is reported of melting of a snow layer in an aqueous solution. A diffusion-controlled analytical model was proposed to the melting under an ideal condition that an aqueous solution was instantaneously filled up by a snow layer at the same temperature as the solution. The analytical results gave a qualitative prediction of the experimental results of the melting of snow layers suddenly immersed in a calcium chloride aqueous solution. The temperature in a melting system decreased rapidly during the melting process. The melting was complete within a few seconds, which denoted a thermodynamic equilibrium. When the initial temperatureT i and the initial porosity of snow ɛ i were the same, the initial concentrationC mi in the solution strongly affected both the decrease in temperature in the melting system and the melting mass per unit volume of snowM. WhenC mi andT i were the same, the maximum melting mass per unit volume of snowM max was not largely affected by snow particle diameters. A figure was presented for the relationM max−T i,C mi, and ɛ i , and also a relationship was presented to easily predict the non-dimensional maximum melting massM max * .
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1434-601X
    Keywords: 21.10.−K ; 21.60.−n ; 25.70.−z ; 27.70.+q
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The strongly shape driving πh9/2[541]l/2− configuration with α=+1/2 exhibits some anomalous, and so far unexplained, features concerning the crossing frequency, ħωc, the aligned angular momentum, ix, and interaction strength, at the alignment of the first pair of i13/2 quasineutrons in several odd-Z rare earth-nuclei. The h9/2[541]1/2− and h11/2[523]7/2− bands have been studied in the stably deformed rare-earth nucleus163Tm to investigate these features. A difference in band crossing frequency of ∼ 80 keV between the two bands is found. Rotational bands built on these two configurations have been found to cross in the spin range I=25/2–29/2 ħ. Theγ-decay pattern between the two bands is established in the crossing region and analysed in terms of a moderate shape difference between them. A theoretical estimate of the size of the interaction strength between the two bands is presented and compared to the experimental value. The observed band structure in163Tm is very similar to that of167Lu which has 2 protons and 2 neutrons in addition. This observation is discussed in relation to the similarity of the yrast bands of the two even-even “core” nuclei162Er and166Yb, for which theγ-transition energies are identical within ∼0.2 keV below the vi13/2 crossing.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1434-601X
    Keywords: 21.10.−k ; 27.60. +j
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new high-spin isomeric state with a half-life of ≥2μs was found in144Pm by observing the14N(136Xe,6n)144Pm reactions. The excitation energy and spin of the isomer were estimated to be ∼7.4 MeV and ∼27+, respectively. Filling gas in a recoil ion separator was used as the target material.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1434-601X
    Keywords: 21.10.-k ; 27.60.+j
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract High-spin states of145Sm were studied by using the20Ne(136Xe, α7n),139La (10B, 4n) and138Ba(13C,6n) reactions. The decay scheme of a high-spin isomer of145Sm was established. The excitation energy and the spin-parity of the isomer were determined to be 8.8 MeV and (49/2+), respectively. The level scheme was extended up to the (65/2) state at 14.6 MeV. The experimental results were discussed comparing with the deformed independent particle model (DIPM) calculation.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1434-601X
    Keywords: 23.20.Lv ; 25.70.Gh ; 27.60.+j
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The level scheme of 143 Eu has been extended to I=75/2 in an experiment with the NORDBALL Compton-suppressed Ge detector array and the 110 Pd(37 Cl, 4n) reaction. Most of the scheme shows irregular structure of multiparticle excitations. A strongly populated straight cascade of more than 10 stretched E2 transitions suggests the onset of collectivity.
    Type of Medium: Electronic Resource
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