Fine Structure Of Spectral Lines Research Articles

Optical properties of antimicrobial barrier layers based on polyethylene terephthalate with a nanostructured surface

The optical properties of nanostructured barrier layers based on polyethylene terephthalate formed by ion technology and their resistance to biodegradation are discussed. The influence of the surface energy and relief parameters on the antimicrobial activity of nanostructured barrier layers is established. The study of reflection spectra demonstrates the fine structure of spectral lines apparently connected with the scattering of electromagnetic radiation by charged centers. These centers are formed on a nanostructured polymer surface after ion-plasma treatment as well as upon the deposition of α-C:H films which are known as electrets with a large number of broken bonds.

High-resolution optical spectroscopy ofTm3+ions inLiYF4: Crystal-field energies, hyperfine and deformation splittings, and the isotopic structure

High-resolution optical Fourier spectroscopy was used to study the energies and widths of the crystal-field (CF) levels, hyperfine and deformation level splittings, and isotopic effects in the ${\text{LiYF}}_{4}:{\text{Tm}}^{3+}$ single crystals. We present the corrected sets of the CF levels and CF parameters for the ${\text{Tm}}^{3+}$ ion in ${\text{LiYF}}_{4}$. The observed fine structure of spectral lines is shown to be caused by the hyperfine interaction, random lattice deformations, and isotopic disorder in the lithium sublattice. From a comparison between the observed and calculated fine structures we determine the characteristics of the random lattice deformations in highly diluted activated crystals and obtain an estimate of the fluorine displacements $(\ensuremath{\sim}3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}\text{ }\text{nm})$ in the nearest surrounding of the mass defect at the lithium site.

Once-ionized Helium in Superstrong Magnetic Fields

It is generally believed that magnetic fields of some neutron stars, the so-called magnetars, are enormously strong, up to 1014-1015 G. Recent investigations have shown that the atmospheres of magnetars are possibly composed of helium. We calculate the structure and bound-bound radiative transitions of the He+ ion in superstrong fields, including the effects caused by the coupling of the ion's internal degrees of freedom to its center-of-mass motion. We show that He+ in superstrong magnetic fields can produce spectral lines with energies of up to ≈3 keV, and it may be responsible for absorption features detected recently in the soft X-ray spectra of several radio-quiet isolated neutron stars. Quantization of the ion's motion across a magnetic field results in a fine structure of spectral lines, with a typical spacing of tens of electron volts in magnetar-scale fields. It also gives rise to ion cyclotron transitions, whose energies and oscillator strengths depend on the state of the bound ion. The bound-ion cyclotron lines of He+ can be observed in the UV-optical range at B 1013 G, and they get into the soft X-ray range at B 1014 G.

VARIABILITY OF FUNDAMENTAL CONSTANTS

Are universal fundamental constants really constant over cosmological times? Recent observations of the fine structure of spectral lines in the early universe have been interpreted as due to a variation of the fine structure constant e2/4πε0ℏc. From the assumed validity of Maxwell equations in general relativity and well known experimental facts, it is proved that e and ℏ are absolute constants. On the other hand, the speed of light need not be constant.

Fine structure of spectral lines in LiYF 4:Er 3+ due to isotopic disorder in the lattice

We report the first observation of the resolved structure in the 4I 15/2→ 4I 13/2 infrared transition of LiYF 4:Er caused by lithium isotopes of the lattice. Isotope shifts of 0.019 and 0.016 cm −1 and inhomogeneous linewidths of 0.010 and 0.007 cm −1 were measured for the lines 6534.3 and 6538.3 cm −1, respectively. Unresolved structure due to different erbium isotopes totals ∼0.010 cm −1.

Analysis of single- and double-crystal spectrometers using three-dimensional DuMond diagrams and the high-precision measurement of the Cu Kα1 line profile

The general principles of single- and double-crystal spectrometers are described using the three-dimensional DuMond diagram and new formulae for the resolution of the spectrometers are deduced. A method for measuring the fine structure of spectral lines with high precision is suggested and a generalized method of refraction correction is discussed. The Cu Kα line profile is measured carefully by double-crystal spectrometers using (nS, nS) and (nV, nR) arrangements, and a hump is found unambiguously on the long-wavelength side of the Cu Kα1 line.

Influence de la Structure Fine des Raies de l'Hélium sur les Mesures de Concentration d'Atomes Métastables par Absorption Optique

We have obtained an algebraic relation taking into account the fine structure of spectral lines in the calculation of metastable atom density. Typical numerical results show that at high optical absorption errors of the order of 100% will result if we neglect the fine structure of lines.

The Optical Properties of the Grating Interferometer

Observations made with the grating interferometer suggest that it may be useful for the study of fine structure. It is hoped that the peculiarities of the instrument and a satisfactory procedure for its application to a study of fine structure of spectral lines can be described in a later paper. At present certain optical properties of the instrument are catalogued. The optical properties are themselves interesting and will be found useful in discussing applications which may be described subsequently.

The Fine Structure of Spectral Lines of Light Scattered by Liquids

GROSS1 has investigated by means of an echelon grating the fine structure of spectral lines scattered by liquids, and has found that in addition to the lines scattered without change of wave-length there appear new lines symmetrically situated relatively to the primary ones. The number of those new lines depends from the substance investigated, and the distance between them depends upon the angle formed by the incident and the dispersed rays.

Zeeman effects for fine structure components of thallium spectral lines

For many years the study of the Zeeman effect with various types of spectra lines has been a very successful method of investigating the electronic features of atomic structure. More recently it has proved to be a successful means of investigating some of the characteristics of atomic nuclei. Certain considerations now being brought forward, associate the fine structure of spectral lines with the spin of the nuclei of the atoms in which the radiation originates. As spectral lines with fine structure components having separations of a considerable magnitude have been found in the spectra of thallium and other elements, it is evident that in a study of the Zeeman effects for these components with magnetic fields of various strengths, a very promising filed of investigation has been created. In the investigation top be described initially to securing Zeeman effects for certain prominent lines in the spark spectrum of thallium in order to obtain information which would lead to their correct classification. While this work was in progress, other investigators, utilising the information at hand concerning the spectra of Hg I and Pb III, were able to assign classifications to a few of the wave-lengths of thallium II in question. These results are now embodied in the publication of a more extensive analysis by McLennan, McLay and Crawford ( loc. cit .). It was thought well, however, to continue the Zeeman effect investigation having in mind either the confirmation of their classification or the extension of the information available regarding the Zeeman effect with elements of high atomic number. In general, the spectra of such atoms indicate interesting quantum vector coupling types.

A Theory of the Gravitational Field in the Light of Maxwell's Theory

In this paper, a complete physical theory of the gravitational field is formulated, which, without recourse to the hypothesis of equivalence or of non-Euclidean geometry, has yet all the advantages of Einstein's theory for describing inertial and gravitational phenomena. The theory starts from the fact that gravitational forces obey the inverse square law in common with electric and magnetic forces; from this it is inferred that Newton's law of gravitation must be developed into a theory of field-action on much the same lines as Coulomb's law has followed; as a first step towards this, the two principles, namely, Hamilton's principle and the special principle of relativity, on which Maxwell's theory is founded, are shown to be sufficient to determine uniquely Lorentz's law of electromagnetic force. Analogous considerations on the same two principles are also found to determine uniquely the law of motion in a gravitational field represented by an invariant potential. The law is found to be a comprehensive law of motion under both inertia and gravitation---the two effects being recognised as only different aspects of the same phenomenon; all the principles of mechanics including the theorems of energy and momentum are actually deduced from the laws of gravitation and the equality of inertial and gravitational mass is proved. Newton's inertial frame is also shown to mark a fundamental physical medium in which matter is embedded---a conclusion confirmed by the experimental detection of this frame by Foucault's pendulum and by the gyro-compass.Applications of the theory.---The theory also shows that this medium is modified near large masses such as the sun and this modification is found to be responsible for the observed values of the spectral shift and of the deflection of light. The fine-structure of spectral lines and the so-called variation of electronic mass with velocity also follow from the theory. The question of Mercury's perihelion is also discussed and it is considered that the problem of perturbations must be treated as a whole in the light of the present law, and a re-examination on the observational side also must be entered into, before the Mercury problem can be dealt with with certainty.

II—Observations on the Structure of the Hydrogen Lines Hα and Hβ

According to Sommerfeld's theory of the fine structure of spectral lines, the magnitude of the separation of the doublets for all the members of the Balmer series of hydrogen should be constant, and have a value of 0·365 cm.−1. Now, owing to the extreme lightness of the hydrogen atom, a direct proof of Sommerfeld's theory by observation of the hydrogen lines is a somewhat difficult undertaking. At ordinary temperatures the Doppler effect is considerable, so that the lines are broadened out and the components of the doublets tend to overlap. The atom of helium, however, is four times as heavy as that of hydrogen, while the nuclear charge is double, so in consequence the separation of the doublets should be, according to the theory, sixteen times as great.

Spectra of Isotopes

THE quantum theory of line spectra developed by Bohr has been most successful in explaining the spectrum of hydrogen and helium, and by a further hypothesis the spectra of the alkali metals. By asserting that elliptic orbits are possible, as well as circular orbits, Sommerfeld succeeded in explaining the Stark and Zeeman effects and the fine structure of spectral lines. It is significant that Bohr's equation for the frequency of the spectral series also explains the difference between the series spectra of isotopes of the same element. The experiments of Aronberg and Merton on the structure of 4058 A. of isotopes of lead showed, however, a remarkable discrepancy between the shift predicted by the theory and that actually observed. Similarly Merton's experiments on the line 6708 of lithium showed that the line consisted of two components 0·151 A. apart, while the theoretical shift was 0·087 A. The quantum theory is unable to account for this large separation observed.

A Combination of a Concave Grating with a Lummer-Gehrcke Plate or an Echelon Grating for Examining Fine Structure of Spectral Lines

A Combination of a Concave Grating with a Lummer-Gehrcke Plate or an Echelon Grating for Examining Fine Structure of Spectral Lines