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The Schrodinger equation in higher dimensions is considered. It consists of the kinetic energy part given by the corresponding Laplace operator, and a term describing the interaction with the electrostatic field of a point charge. From Rutherford-type scattering experiments one can conclude that the potential of a point charge is ∼1/r irrespective of the dimension of the space where the experiment is carried through. Also the structure of the kinetic energy is unchanged in higher dimensions so that one is lead to the result that there exist stable atoms in higher spatial dimensions d⩾4. The solutions and energy eigenvalues to this Schrodinger equation in higher dimensions are presented. As a consequence, the dimensionality of space can be read off from the spectral scheme of atoms: The three-dimensionality of space is a consequence of the existence of the Lyman series. Another consequence is that the Maxwell equations in higher dimensions must be modified in order to have the 1/r-potential as solution for a point charge.

A stationary, electronically excited, population inversion of atomic hydrogen, H, has been observed in a low-pressure water-vapor microwave discharge plasma. The inverted H population was evident from the relative intensities of the transitions within the Lyman series (n=2, 3, 4, and 5 to n=1) and within the Balmer series (n=3, 4, 5, 6, 7, and 8 to n=2). Back illumination with a broadband (vis/IR) lamp source showed depopulation of the n=5 state. Lines of the Balmer series of n=5, and 6 to n=2 and the Paschen series of n=5 to n=3 were of particular importance because of the potential to design blue and 1.3 μm infrared lasers, respectively, which are ideal for many communications and microelectronics applications. High-power hydrogen gas lasers are anticipated at wavelengths over a broad spectral range from far infrared to violet which may be miniaturized to micron dimensions. Such a hydrogen laser may prove to be the most versatile and useful of all.

It is found that abrading two opposing surfaces of either crystalline Si or Ge samples results in homogeneous, uniaxial stress throughout the bulk perpendicular to the damaged surfaces. The latter are chosen to coincide with simple crystallographic planes. This conclusion is reached by analyzing the splittings, intensities, and polarizations of the absorption lines of the Lyman series of bulk shallow impurities in the abraded semiconductors. This effect has been observed for samples which range in thickness, t, from 1 to 3 mm, the internal stress being proportional to t−1.

The reflective properties of a flat Mo/Si multilayer mirror (MLM) optimized for the 230 A

Extended spectroscopic measurements of hydrogen emission into the vacuum ultraviolet region on the Maryland Centrifugal Experiment [R. F. Ellis, A. B. Hassam, S. Messer, and B. R. Osborn, Phys. Plasmas 8, 2057 (2001)] indicate, from opacity on the Lyman series, ∼6% atomic hydrogen coexisting with protons, electrons, and carbon-impurity ions in a plasma region where the temperature is ∼15eV. An explanation is offered, based upon charge exchange of entering cold hydrogen atoms with plasma protons, followed by collisional excitation and radiative decay.

This work is related to a recent development of a data acquisition and control system for high‐resolution EUV spectroscopy following ion–atom and ion–molecule collisions. The system consists of a personal computer, an IEEE‐488 interface board, and a CAMAC system, which includes a GPIB crate controller, a stepping motor controller, and two 32‐bit up–down counters. A unique software ‘‘DATACQ’’ for data acquisition and control has been designed and tested to simplify complex spectroscopy applications. As a prototype case, EUV spectra of the Lyman series of He+ following simultaneous ionization and excitation of He by fast H+, H+2, and H+3 impact are presented here.

We have measured the electron impact emission cross sections for CH4 and C2H2 at 200 eV in a crossed beam laboratory system. Included in the study are all vacuum ultraviolet (VUV) emission features from 40 to 200 nm. The features are entirely from the atomic dissociation fragments (C i, C ii, and H). The Lyman series of H is observed to truncate near principal quantum number n=10 due to the long lifetime and to the high kinetic energy of the excited H fragments. The threshold region of the excitation functions has been measured at an energy resolution of 0.2–1.0 eV for the Lyman‐α and Lyman‐β transitions of H and C i (165.7, 193.1 nm) multiplets; and several distinct appearance potentials (AP) have been detected. For example, appearance potentials of Lyman‐α from dissociation of CH4 and C2H2 are noted at several energies, including the first observations of a Lyman‐α AP from C2H2 at 16.3 eV.

Photodissociation of water vapor to produce H(n=2) atoms was examined from threshold to 500 A. The experimental threshold of 813.0 A nearly coincides with the thermodynamic limit. Excitation cross sections rise slowly from threshold to a maximum value of (1.55±0.12) ×10−18 cm2 at ∼709 A and decreases to a negligible value below 550 A. Structure in the excitation function is attributed to predissociation of Rydberg series converging to the ? 2B2 state of H2O+.

A more general description of the Cotton—Mouton effects in atoms and molecules is presented. By use of a time‐dependent double perturbation approach, closed and spectral expansion expressions of required molecular parameters are derived. The method is applied to the hydrogen atom to generate accurate Cotton—Mouton dispersion curves for a wide range of wavelengths, including the first two lines of the Lyman series.

The LCAO–MO–CI method is applied to the study of the electronic transition moment of the Lyman bands of H2 (B 1Σu+–X 1Σg+) over the range of internuclear separations 1 ≤ R ≤ 6 a.u. It is found that configuration interaction is responsible for a strong nonlinear variation of the transition moment with internuclear distance (maximum transition moment at 3.0 a.u.). Comparison with other calculations indicates that the method is applicable to more complicated molecules and permits the examination of how individual electron correlation effects contribute to the transition moment.

Single shot photographic spectra of hydrogen‐like aluminum Lyman series lines are obtained from a low inductance vacuum spark. Corresponding pinhole pictures yield information on the source size. The observed line profiles are found to increase in width along the series and the higher series members Lγ and Lδ can be matched with convolved Stark and Gaussian profiles. The Gaussian profile includes the effects of source size, thermal Doppler broadening, and crystal resolution. The space and time‐averaged electron density determined from the profile analysis is 2.5×1021–1×1022 cm−3.