Multiphoton detachment of H-

This is the published version, also available here: http://dx.doi.org/10.1103/PhysRevA.48.4654.Multiphoton detachment of H- is considered. An accurate one-electron model, which reproduces precisely the known H- detachment energy and the low-energy e-H(1s) elastic-scattering phase shifts, is developed. Generalized cross sections, based on lowest-nonvanishing-order perturbation theory, are evaluated by an accurate and efficient numerical algorithm for the solution of the associated set of inhomogeneous differential equations. Two- to eight-photon detachment cross sections are determined and compared with a recent one-electron model and two-electron ab initio calculations. It appears that the present study provides consistent results with an accuracy for higher-order (n>3) photon-detachment cross sections comparable to that of lower orders (n=2,3). Average detachment rates for linearly polarized light are calculated and compared with recent experimental measurements. It is found that, for higher-order photon detachment, the rates for circular polarization are small in comparison with the rates for linear polarization

Spectral and temporal structures of high-order harmonic generation of Na in intense mid-ir laser fields

This is the published version, also available here: http://dx.doi.org/10.1103/PhysRevA.64.013406.We present a three-dimensional quantum study of high-order harmonic generation (HHG) of the Na atom in intense mid-ir laser fields. An accurate one-electron model potential is constructed for the description of the Na atom. The time-dependent Schrödinger equation is solved by means of the time-dependent generalized pseudospectral method, allowing nonuniform and optimal spatial grid discretization and accurate and efficient propagation of the wave function in space and time. Excellent agreement of the HHG spectrum in the length and acceleration forms is obtained from the lowest harmonics up to the cutoff. The HHG power spectrum shows fine structures and significant enhancement of the intensities of the lower harmonics due to the strong coupling of the 3s−np states and the 3s−3p multiphoton resonance. We use a wavelet transform to present a detailed time-frequency analysis of the whole range of the HHG power spectrum. The results reveal striking details of the spectral and temporal fine structures of HHG, providing insights into different HHG mechanisms in different energy regimes of Na atoms at long wavelengths

Multiphoton detachment of H-. II. Intensity-dependent photodetachment rates and threshold behavior—complex-scaling generalized pseudospectral method

This is the published version, also available here: http://dx.doi.org/10.1103/PhysRevA.50.3208.We extend our previous perturbative study of the multiphoton detachment of H- [Phys. Rev. A 48, 4654 (1993)] to stronger fields by considering the intensity-dependent photodetachment rates and threshold behavior. An accurate one-electron model potential, which reproduces exactly the known H- binding energy and the low-energy e-H(1s) elastic-scattering phase shifts, is employed. A computational technique, the complex-scaling generalized pseudospectral method, is developed for accurate and efficient treatment of the time-independent non-Hermitian Floquet Hamiltonian H^F. The method is simple to implement, does not require the computation of potential matrix elements, and is computationally more efficient than the traditional basis-set-expansion–variational method. We present detailed nonperturbative results of the intensity- and frequency-dependent complex quasienergies (ER,-Γ/2), the complex eigenvalues of H^F, providing directly the ac Stark shifts and multiphoton detachment rates of H-. The laser intensity considered ranges from 1 to 40 GW/cm2 and the laser frequency covers 0.20–0.42 eV (in the c.m. frame). Finally we perform a simulation of intensity-averaged multiphoton detachment rates by considering the experimental conditions of the laser and H- beams. The results (without any free parameters) are in good agreement with experimental data, both in absolute magnitude and in the threshold behavior

Laser-assisted charge-transfer reactions (Li(3)(+)+H): Coupled dressed-quasimolecular-state approach

This is the publisher's version, also available electronically from http://journals.aps.org/pra/abstract/10.1103/PhysRevA.32.122.A semiclassical coupled dressed-quasimolecular-states (DQMS) approach is presented for nonperturbative treatment of multichannel charge-transfer reactions at low collision velocities and high laser intensities, incorporating the implementation of the generalized Van Vleck (GVV) nearly degenerate perturbation theory. The GVV technique allows block partitioning of the infinite-dimensional Floquet Hamiltonian into a finite-dimensional model DQMS space, and thereby reduces greatly the number of effective coupled channels. Further, the GVV-Floquet basis allows minimization of the (usually large in amplitude) field-induced nonadiabatic radial couplings without the need to explicitly construct the transformation between the adiabatic and diabatic DQMS basis. This yields a new set of coupled GVV-DQMS equations (neither adiabatic nor diabatic) which are particularly convenient for multichannel calculations. The method is applied to the study of the laser-assisted charge-transfer process: Li(3+)+H(1s)+ħω→Li(2)+(n= 3)+H(+), using 2-, 5-, and 15- GVV-DQMS basis. It is found that while the 5-state results agree well with the 15-state calculations even up to very high intensities for the (LiH)3+ system, the 2-state basis is inadequate at high-intensity and lower-wavelength regimes. Detailed results and nonlinear dynamical features are presented for the process at small impact velocity 10(7) cm/s and strong laser fields with intensity ranging from 1 to 100 TW/cm(2) and wavelengths from 1500 to 3000 Å

Two‐photon dissociation of vibrationally excited HD+: The inhomogeneous differential equation approach

This is the published version, also available here: http://dx.doi.org/10.1063/1.451229.We extend the inhomogenous‐differential‐equation (IDE) approach of Dalgarno and Lewis for a detailed study of two‐photon dissociation (TPD) of HD+ from high vibrational levels of the 1sσ g electronic state. Contrary to the H+ 2 case, where the TPD cross sections σ(2) L are largest near TPD thresholds and decrease monotonically with increasing photon energy, the HD+ cross sections are characterized by rich resonant and interference structures. We present σ(2) L results for TPD from the initial v i =6, 8, 10, 12, 14, 16, and j i =0 levels as well as from v i =14, j i =0, 2, 4 levels for a wide range of wavelengths of linearly polarized radiation accessible by CO2 and CO lasers. It is found that while there are four TPD pathways, the channel 1sσ g (v i   j i )→ω 1sσ g (v, j=j i ±1) →ω2pσ u (k, j   f =j±1) dominates the two‐photon process in most of the cases we have studied. Further, the results show that σ(2) L increases rather rapidly as the initial vibrational quantum number v i increases, indicating that the hereronuclear diatomic molecules in high vibrational levels can be efficiently two‐photon dissociated by IR lasers. Consequently molecular structures near the dissociation limit may be conveniently probed by two‐photon spectroscopy—as has indeed been demonstrated recently by experiments. Our σ(2) L results thus provide complementary information to the HD+spectroscopic data obtained recently by Carrington e t a l

Farm corporations, recent developments and economic considerations

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Dynamical origin of near- and below-threshold harmonic generation of Cs in an intense mid-infrared laser field

Near- and below-threshold harmonic generation provides a potential approach to generate vacuum-ultraviolet frequency comb. However, the dynamical origin of in these lower harmonics is less understood and largely unexplored. Here we perform an ab initio quantum study of the near- and below-threshold harmonic generation of caesium (Cs) atoms in an intense 3,600-nm mid-infrared laser field. Combining with a synchrosqueezing transform of the quantum time-frequency spectrum and an extended semiclassical analysis, the roles of multiphoton and multiple rescattering trajectories on the near- and below-threshold harmonic generation processes are clarified. We find that the multiphoton-dominated trajectories only involve the electrons scattered off the higher part of the combined atom-field potential followed by the absorption of many photons in near- and below-threshold regime. Furthermore, only the near-resonant below-threshold harmonic is exclusive to exhibit phase locked features. Our results shed light on the dynamic origin of the near- and below-threshold harmonic generation.This work was partially supported by the Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, US Department of Energy. P.-C.L. is partially supported by the National Natural Science Foundation of China (grants nos. 11364039 and 11465016), the Natural Science Foundation of Gansu Province (grant no. 1308RJZA195) and the Education Department of Gansu Province (grant no. 2014A-010). We also would like to acknowledge the partial support of the Ministry of Science and Technology and the National Taiwan University (grants nos NTU-104R104021 and NTU-ERP-104R8700-2). We would also like to thank Dr Tak-San Ho and Liang-Yan Hsu (Princeton University) and Dr Dmitry A. Telnov (St Petersburg State University) for helpful discussions and suggestions

New Oklahoma gift tax law and its implications

The Oklahoma Cooperative Extension Service periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311

Abandoned mineral interests

The Oklahoma Cooperative Extension Service periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311

Laser assisted charge transfer reactions in slow ion–atom collisions: Coupled dressed quasimolecular‐states approach

This is the published version, also available here: http://dx.doi.org/10.1063/1.447712.Semiclassical coupled dressed quasimolecular states (DQMS) approaches are presented for the nonperturbative treatment of charge transferreactions at low collision velocities and high laser intensities. The DQMS are first obtained via the Floquet theory. The laser assisted collision process can then be treated as the electronic transitions among the DQMS driven by the nuclear motion only. The expansion of the total electronic wave function in a truncated DQMS basis results in a set of coupled a d i a b a t i c equations. The adiabatic DQMS and their associated quasienergies (depending parametrically upon the internuclear separation R) exhibit regions of avoided crossings, where the electronic transition probabilities are large due to strong radial couplings induced by the nuclear movement. By further transforming the a d i a b a t i c DQMS into an appropriate d i a b a t i c DQMS representation, defined via the vanishing of the aforementioned radial couplings, we obtain a new set of coupled d i a b a t i c equations which offer computational advantage. The method is illustrated by a case study of the laser assisted charge exchange process He+ ++H(1s)+ℏω→He+(n=2)+H+, in a two‐state approximation, for the velocity range from 1.5×105 to 2×107 cm/s and for the laser intensity in the range of 0.4 to 4.0 TW/cm2. Results of exact coupled diabatic DQMS calculations are presented along with several approximation calculations, using first order perturbation theory, the Magnus approximation, and the average cross section