Scaled-Energy Floquet Spectroscopy in a Strong Electric Field: A Semiquantal Calculation of the Recurrence Spectrum

We consider a hydrogen atom in a strong static electric field with a weak parallel radio-frequency (rf) field. We compute the photoabsorption spectrum by calculating the spectrum of Floquet states, including their quasienergies and their oscillator strengths. Our calculation is based upon “semiquantal” formulas: we calculate the discrete spectrum of quasienergy states by using a quantum adiabatic approximation combined with semiclassical (Bohr-Sommerfeld) quantization rules. We express this spectrum in a manner consistent with the method of scaled-variable spectroscopy, and then calculate the Fourier transform. These calculated absorption spectra and recurrence spectra are in good agreement with experiments on Li atoms. Additional approximations show that the recurrence spectrum is approximately equal to the product of the recurrence spectrum in a static field times an envelope function. That envelope function is the Fourier transform of a cluster of sidebands surrounding a progenitor level in the rf field. The resulting formula agrees with the low-frequency limit of a formula obtained from a semiclassical treatment

Semiclassical Formula for Oscillator Strengths in Atomic Spectra

A simple semiclassical formula is given for the oscillator strengths of high Rydberg states of a hydrogen atom in an electric field. The oscillator strength of a state is proportional to the square of the function representing the quantum angular distribution of outgoing waves, evaluated at the classical angle of ejection from the atom that sends the electron into a semiclassically quantized eigentrajectory. The formula gives an interpretation of the envelopes of Stark manifolds in photoabsorption spectra; it is in good agreement with quantum calculations. The formula may also be used for other integrable or near-integrable systems

Semiclassical Formula for Oscillator Strengths of Atomic Spectra in External Fields

In a previous Rapid Communication [Phys. Rev. A 56, R5 (1997)] we reported a semiclassical formula describing oscillator strengths for transitions to a high Rydberg state of a hydrogen atom in an electric field. The formula relates the oscillator strength for an atomic transition into a Rydberg state to the angular distribution of outgoing electron waves and to the density of classical tori. Here we give a derivation of that formula and we suggest some generalizations. We compare the formula with experimental measurements of the absorption spectrum of hydrogen in an electric field. This absorption spectrum consists of quasidiscrete resonances superposed on a smooth background. We find that this background has a hitherto unexplained structure that was visible but not recognized in the experiment. The background absorption is related to electron orbits that directly escape from the atom, and its structure is related to the angular distribution of outgoing electrons

Photodetachment of H−^{-} near a partial reflecting surface

Theoretical and interpretative study on the subject of photodetachment of H$^{-}$ near a partial reflecting surface is presented, and the absorption effect of the surface is investigated on the total and differential cross sections using a theoretical imaging method. To understand the absorption effect, a reflection parameter $K$ is introduced as a multiplicative factor to the outgoing detached-electron wave of H$^-$ propagating toward the wall. The reflection parameter measures, how much electron wave would reflect from the surface; K=0 corresponds to no reflection and K=1 corresponds to the total reflection.Comment: 8 pages, 4 figure

Classically Forbidden Recurrences in the Photoabsorption Spectrum of Lithium

We present data on the photoabsorption spectrum of lithium atoms in an electric field at energies between the saddle point of the Stark potential and below the field-free ionization threshold. The spectrum displays a sequence of sharp resonances and a sequence of broad ones. We find that the broad resonances arise from the classically forbidden reflection of waves above a dynamical potential barrier. The recurrence spectrum is also observed and it is dramatically affected by above-barrier reflections. We have developed a semiclassical theory that interprets the spectra using quasiclassical trajectories that undergo above-barrier reflection

Semiclassical Representation of Width-Weighted Spectra

We consider a system having decaying states with complex energies Ej−iΓj/2, and we define the “width-weighted spectrum” as DΓ(E)=ΣjΓjδ(E−Ej). We derive a semiclassical formula for this width-weighted spectrum, a formula which is analogous to the periodic-orbit representation of the density of states. The formula applies if classical motion is regular and if decay occurs by tunneling through a barrier. The semiclassical formula involves not periodic orbits or closed orbits, but action integrals associated with irreducible loops on the “extremal torus,” on which the particle climbs up the barrier and hangs at the top. Calculations confirm the validity of the formula

Semiclassical Theory of Weighted Spectra for Regular Systems: Absorption Spectra and Decay Rates

We derive a simple semiclassical representation to describe the large-scale structure of the spectrum of regular systems weighted by some arbitrary function W. Examples of weighted spectra are the width-weighted spectrum, which represents the decay rate of an unstable system, and the oscillator-strength-weighted spectrum, which represents the photoabsorption rate. Semiclassical representations of such spectra involve stationary-phase contributions, which are periodic or closed orbits, and end-point contributions, which are loops on an extremal torus. The theory provides the link between semiquantal formulas and the closed-orbit theory of atomic photoabsorption. It also allows calculation of an average decay rate without knowledge of the widths of individual quantum states

Semiclassical quantization with bifurcating orbits

Bifurcations of classical orbits introduce divergences into semiclassical spectra which have to be smoothed with the help of uniform approximations. We develop a technique to extract individual energy levels from semiclassical spectra involving uniform approximations. As a prototype example, the method is shown to yield excellent results for photo-absorption spectra for the hydrogen atom in an electric field in a spectral range where the abundance of bifurcations would render the standard closed-orbit formula without uniform approximations useless. Our method immediately applies to semiclassical trace formulae as well as closed-orbit theory and offers a general technique for the semiclassical quantization of arbitrary systems

Peculiarities of personnel motivation system and its role in the management of the company «Mouzenidis Travel»

The relevance of consideration issues of motivation aspects in modern management is becoming increasingly important. Creating well-developed systems of management of labor motivation of employees of the organization helps make optimum use of available human resources. The article considers the theoretical foundations of motivation, the results of research activities on the motivation of firm personnel, and assessment of motivation as a key to the success of the company «Mouzenidis Travel», developed proposals on improvement of activity of tourist firms, connected with the issues of personnel motivation as a major factor of effective activity of enterprise personnel.Актуальность рассмотрения проблем мотивационных аспектов в современном менеджменте приобретает все большее значение. Создание четко разработанных систем управления трудовой мотивацией сотрудников организации способствует оптимальному использованию имеющегося кадрового потенциала. В статье рассмотрены теоретические основы мотивации, представлены результаты исследований направлений деятельности по мотивации персонала фирмы и оценки состояния мотивации как залога успешной деятельности компании «Mouzenidis Travel», разработаны предложения по совершенствованию деятельности туристской фирмы, связанными с вопросами мотивации персонала как главного фактора эффективной деятельности персонала предприятия на основе собственного практического опыта работы в данной компании

Recurrence Spectroscopy of a Time-Dependent System: A Rydberg Atom in an Oscillating Field

We report the results of an experimental and theoretical investigation of the recurrence spectra of Rydberg atoms in a static plus weak oscillating electric field. Experiments reveal the systematic weakening of orbits in a recurrence spectrum as the oscillating field strength and frequency are changed. We describe a generalization of closed orbit theory to time-dependent systems and show that it provides a qualitative and quantitative description of the phenomena