scholarly journals Intensity measurements in a fine structure multiplet of As II

1934 ◽  
Vol 146 (859) ◽  
pp. 818-824 ◽  
Keyword(s):  
Fine Structure ◽  
Intensity Distribution ◽  
Nuclear Spin ◽  
Inherent Difficulty ◽  
Intensity Measurements ◽  
Fine Structures ◽  
Intensity Ratios ◽  
Instrumental Intensity ◽  
Spin Multiplet

The present work was undertaken with the object of testing the fine structure intensity formulæ deduced by Hill. Up to the present very few intensity measurements have been made on the fine structures arising from nuclear spin. The principal difficulty in such measurements arises from the smallness of the structures which are usually incompletely resolved by the interferometers employed. The use of the interferometer in any event necessitates careful corrections for the instrumental intensity distribution. Schüler and Keyston have made photometric determinations of the intensity ratios in the fine structures of two Cdl lines and have verified the intensity rules for these lines. An inherent difficulty in the examination with a FabryPerot interferometer of Cdl structures lies in the presence of an intense evei isotope line within the pattern due to the nuclear spin of the odd isotopes The even isotope component contributes 77% of the intensity of the line and the remaining 23% is distributed amongst the members of the nuclear spin multiplet. The authors do not describe their method of coping with this difficulty which, judging from the experience of the present writers, must have been serious.

scholarly journals The nuclear spin of iodine I— fine structure in the first spark spectrum

1935 ◽  
Vol 149 (867) ◽  
pp. 269-281 ◽  
Keyword(s):  
Fine Structure ◽  
High Resolution ◽  
Nuclear Spin ◽  
High Frequency ◽  
Complete Resolution ◽  
Electrodeless Discharge ◽  
A Value ◽  
Fabry Perot ◽  
Fine Structures ◽  
The Individual

In an earlier paper on the fine structures of the visible lines in the arc spectra of bromine and iodine an attempt was made to estimate the nuclear spin of iodine, and a tentative value of 9/2 was proposed. The iodine arc lines were excited by a high frequency electrodeless discharge in pure iodine vapour and examined with a silvered Fabry-perot interferometer. The fine structures in the arc lines are small, and as the patterns are highly complex and the individual components not very sharp, interpretation was difficult. It was concluded with certainty that the nuclear spin was at least equal to 5/2, but one line in particular suggested a value of 9/2. This was indefinite, and in view of the uncertainty a thorough examination of both the arc and spark spectra of iodine has been undertaken. A preliminary notice has already appeared. The first spark spectrum can be more easily studied than the arc spectrum, since the structure are on a very much bigger scale and more complete resolution can be attained. The present work is concerned with the spark lines excited in a hollow cathode discharge. Fine structures in iodine spark lines were first recorded long ago by Wood and Kimura who excited the lines in a Geissler tube and examined them with a transmission echelon. Murakawa attempted to analyse the fine structure data, but as the source and instrument employed by Wood and Kimura were not able to give the high resolution attained here, the deductions made from these data, although generally correct, are uncertain and require further examination; for many of the line structures are much more complex than as reported by these earlier observers.

scholarly journals The nuclear spin of arsenic

1932 ◽  
Vol 137 (833) ◽  
pp. 541-558 ◽  
Keyword(s):  
Fine Structure ◽  
Nuclear Spin ◽  
Ultra Violet ◽  
Resolving Power ◽  
Coupling Scheme ◽  
Vector Coupling ◽  
Theoretical Significance ◽  
Fine Structures ◽  
Multiplet Analysis ◽  
Interval Ratio

No fine structure has yet been recorded in any of the lines of the spectra of arsenic. The present paper gives an account of the fine structures of the majority of the visible lines of As II. This spectrum is very rich in strong lines and has been observed here in the region λλ 6400-4300 with high resolving power. The gross structure multiplet analysis of As II has been made by K. R. Rao, and the fine structure observations recorded here support this analysis. The terms expected and found in this spectrum are shown in Table I. All lines involving the 4 s 2 . 4 p 2 configuration lie in the deep ultra-violet region; therefore this configuration will be disregarded in the present investigation. According to the vector coupling scheme of White and Ritsehl it will be expected that the 4 s 2 . 4 p . 5 s configuration will show wide hyperfine structure separations, since it involves an unpaired penetrating s electron; this is actually verified here with some modification. As the 4 s 2 . 4 p . 5 p configuration has no penetrating s electron, only narrow structures are to be expected, but this, however, is not observed, since structures occur in this configuration which are of the same order as those found in the previous case. This has important theoretical significance and will be discussed later. The intervals in the 4 s 2 . 4 p . 5 s triplet terms which are 3 P 0 — 3 P 1 = 397 cm. -1 and 3 P 1 — 3 P 2 = 2382 cm. -1 show that the electron coupling is by no means pure (LS) since the interval ratio deviates widely from the Landé interval rule. In the 4 s 2 . 4 p . 5 p and in the 4 s 2 . 4 p 2 terms the deviations are much less marked. This incomplete (LS) coupling affects the structure and will be considered later.

scholarly journals Fine structure in the mercury singlet terms

1931 ◽  
Vol 130 (815) ◽  
pp. 558-578 ◽  
Keyword(s):  
Fine Structure ◽  
Experimental Work ◽  
Nuclear Spin ◽  
Short Note ◽  
Preliminary Note ◽  
Singlet Level ◽  
Fabry Perot ◽  
Comprehensive Survey ◽  
Fine Structures ◽  
Work Done

The fine structure occurring in a number of line spectra has been reasonably accounted for by the theory of nuclear spin, but up to the present the complexity of the fine structure in mercury lines has remained unexplained, more lines occurring than theory demands. Because of the weakness of the singlets in the sources usually employed most of the investigations on mercury fine structure have been carried out on triplet and intercombination lines. The fine structures in the singlest series should yield more readily to analysis than in the triplet series, being simpler, and for this reason are investigated here. A comprehensive survey of the experimental work done up to 1926 in mercury was given by Ruark who succeeded in accounting for the majority of the components in several triplet lines by giving a number of levels as threefold multiplicity. Only one singlet level 6 1 P 1 was discussed and the multiplicity attributed to this was seven. In a previous communication an account was given of a method for increasing the relative and intrinsic intensity of the singlet series and of inter-combination lines involving upper singlet levels. The series 6 1 P 1 — m 1 S 0 , 7 1 S 0 — m 1 P 1 and 7 3 S 1 — m 1 P 1 are particularly strengthened and these have been examined for fine structure with a Fabry-Perot interferometer. It was stated in a preliminary note that λ 4916 (6 1 P 1 — 8 1 S 0 ) had four components and that the members of the series 7 1 S 0 — m 1 P 1 , 7 3 S 1 — m 1 P 1 were sextet. These observations are now somewhat extended, fainter components having been found. Whilst this paper was in the course of preparation, a communication was received from Venkatesachar and Sibaiya giving the structures of some of these lines. Venkatesachar also stated, that in a short note to 'Nature,' which was overlooked by the writer, Hansen found that λ 4916 was a quintet. These results will be discussed later.

scholarly journals The nuclear spin of iodine II-Fine structure in the arc spectrum and a fine structure perturbation effect

1935 ◽  
Vol 152 (877) ◽  
pp. 663-672 ◽  
Keyword(s):  
Fine Structure ◽  
Hollow Cathode ◽  
Nuclear Spin ◽  
High Frequency ◽  
Electrodeless Discharge ◽  
Partial Resolution ◽  
Fabry Perot ◽  
Fine Structures ◽  
The Individual ◽  
Perturbation Effect

The arc spectrum of iodine was first examined for fine structure by Wood and Kimura,* who failed to detect structure in any of the fines. The failure was probably due to the use of an unsatisfactory source and to the smallness of the resolving powers employed. The author then examined the iodine arc spectrum that was emitted by a high frequency electrodeless discharge in pure iodine vapour, using a variable gap Fabry-Perot interferometer as the resolving instrument. Structure was observed in eleven fines and an attempt at analysis was made. The nuclear spin of iodine was then unknown and, as only partial resolution was achieved, interpretation proved to be very difficult and ambiguous. Furthermore, at that time the existence of fine structure perturbations was not yet even suspected and, as will be shown later, one of the important s terms is perturbed. The nuclear spin of iodine was determined* from extensive measurements of the fine structures in the lines of the first spark spectrum. The lines produced in a water-cooled hollow cathode were investigated and, owing both to the sharpness of the individual components and to the relatively wider structures associated with the ionized atom, an unambiguous value for the spin was found (5/2). Knowing the spin with certainty, this can now be applied to the interpretation of the structures in the arc lines. However, realizing the superiority of the hollow cathode as a source, a complete re-examination of the spectrum was made. This revealed the fact that the previous measurements were all approximately correct, the differences being accounted for by the higher resolution now attained.

scholarly journals Fine structure in the arc spectrum of platinum (A) The nuclear spin of pt 195 (B) Even isotope displacement

1937 ◽  
Vol 158 (893) ◽  
pp. 110-127 ◽  
Keyword(s):  
Fine Structure ◽  
Nuclear Spin ◽  
Atomic Weight ◽  
Central Component ◽  
Nuclear Spins ◽  
Centre Of Gravity ◽  
Mass Spectrograph ◽  
Fine Structures ◽  
Magnetic Splitting ◽  
Platinum Isotope

The platinum isotope 195 has an odd atomic weight and an even atomic number, that is the nucleus contains an odd neutron. It has been shown elsewhere by one of us that the distribution of nuclear spins in the nuclei with an odd neutron is totally different to that in the nuclei containing an odd proton. The number of mechanical moments known for those nuclei with odd neutrons is considerably less than that known for the other type, and for this reason we undertook the examination of the arc spectrum of platinum with a view to ascertaining the nuclear spin from the fine structures. Dempster has investigated the isotopic constitution of platinum with the mass spectrograph and reports the following isotopes, 192, 194, 195, 196, 198, the relative abundances being such that 192 is extremely weak, 194, 195, 196 all about similar, and 198 somewhat weaker than these. It is to be expected from this that some of the arc lines of platinum will exhibit a fine structure pattern due to the magnetic splitting of the 195 isotope and at the centre of gravity of this pattern will be a strong central component due to the grouping together of the even isotope components. If there is even isotope displacement, the centre component will be split up into three, the intensities of which will be such that two are strong and one weak. (The 192 isotope is so weak that it is being entirely neglected in the whole of this discussion.)

scholarly journals Determinations of the Rydberg constants, e / m , and the fine structures of H α and D α by means of a reflexion echelon

1940 ◽  
Vol 174 (957) ◽  
pp. 164-188 ◽  
Keyword(s):  
Fine Structure ◽  
Quantum Theory ◽  
Electron Spin ◽  
Considerable Importance ◽  
Balmer Line ◽  
Fundamental Constants ◽  
Fine Structures ◽  
Intensity Ratios ◽  
Relativity Effect

During the last few years many investigations have been carried out with the object of determining the fine structure of the red Balmer line of Hydrogen, H α , and its corresponding analogue, D α , in the heavier isotope Deuterium. It is only in these cases that the positions and relative intensities of the components can be accurately calculated in terms of the fundamental constants e, h, c , etc. The results are thus of considerable importance as affording a direct check on the fundamental basis of the quantum theory. When account is taken of the effects of electron spin and the relativity variation of mass with velocity, the wave mechanical equations of Dirac give a result for the structure and intensity ratios identical with that given by the “Sommerfeld formula” which was an earlier attempt to make allowance for the relativity effect.

scholarly journals Fine Structure and Dynamics of the Inner Corona

1977 ◽  
Vol 43 ◽  
pp. 9-9
Author(s):  
G.E. Brueckner ◽  
J.D.F. Bartoe ◽  
M.E. VanHoosier
Keyword(s):  
Solar Wind ◽  
Fine Structure ◽  
Thermal Energy ◽  
Column Density ◽  
Line Profiles ◽  
Quiet Sun ◽  
Structure And Dynamics ◽  
Fine Structures ◽  
The Doppler Effect ◽  
Average Size

High spectral (0,05 Å) and spatial (⋍ 1000 km) resolution spectra of the Fe XII line 1349.4 Å reveal the existence of coronal fine structures in the quiet sun against the solar disk. These coronal bright elements have an average size of 2000-3000 km; their column density can be 3 x 1017 cm –2 . In the quiet sun, outward streaming velocities of 10-15 km sec –1 can be measured by means of the Doppler effect. The total kinetic and thermal energy of the outstreaming gas can be estimated to be larger than 1 x 10 5 ergs cm –2 sec –1, enough to account for the heating of the corona and the losses of the solar wind. At the outer limb (cos θ ⋍0.1) line profiles show a strong blue asymmetry, which could be caused by expanding material in a piston-driven shock, whereby the opaque, cool piston causes the asymmetry of the line profile.

Spectra of (H2)2, (D2)2, and H2–D2 Van der Waals Complexes

1974 ◽  
Vol 52 (12) ◽  
pp. 1082-1089 ◽  
Author(s):  
A. R. W. McKellar ◽  
H. L. Welsh
Keyword(s):  
Fine Structure ◽  
Nuclear Spin ◽  
Selection Rule ◽  
Van Der Waals ◽  
Rotational Quantum Number ◽  
Van Der Waals Complexes ◽  
Not Given ◽  
Simple Effect ◽  
Anisotropic Force ◽  
Nuclear Spin Statistics

Spectra due to the Van der Waals complex (H2)2 have been obtained with greatly improved resolution, and analogous spectra of (D2)2 and H2–D2 have been observed. The experiments were conducted with an absorption path of 110 m in a multiple traversal cell at temperatures between 16 and 21 K. The spectra are manifested as fine structure accompanying the single and double H2 (or D2) transitions in the hydrogen (or deuterium) collision induced fundamental band. The observed structure for (H2)2 and H2–D2 can be unambiguously assigned to rotational transitions of the complex governed by the selection rule Δl = ± 1, ± 3, where l is the rotational quantum number of the complex. A detailed analysis must include anisotropic force effects, and is not given here. The spectrum of (D2)2 is complicated, not only by anisotropic force effects, but also by mutual perturbations between the rotational levels of the upper states of corresponding single and double D2 transitions; for this reason, the assignments suggested are somewhat uncertain. An interesting intensity alternation apparent in part of the (D2)2 spectrum is explained as a simple effect of nuclear spin statistics in the pseudodiatomic molecule (D2)2.

scholarly journals The effect of a nuclear spin on the optical spectra.—III

1930 ◽  
Vol 127 (805) ◽  
pp. 407-416 ◽  
Keyword(s):  
Interaction Energy ◽  
Nuclear Spin ◽  
Energy Levels ◽  
Optical Spectra ◽  
Wave Functions ◽  
Orbital Momentum ◽  
Multiplet Structure ◽  
Multiple Wave ◽  
First Approximation ◽  
Intensity Ratios

In two recent papers the author has discussed the effect of a nuclear spin on the optical spectra by the method of multiple wave-functions. In these papers the interaction energy of the nuclear and electron spins was not taken into account, as has been pointed out by Hill. By its omission the equations were simplified considerably, without affecting the intensity ratios of the lines of the multiplet. The problem of finding the relative intensities is a purely kinematical one, depending as it does, to the first approximation, on the un­perturbed wave-functions. In the papers cited we used the interaction energy of the nuclear spin and orbital momentum to find the 4 i n + 2 wave-functions ( i n being the number of quanta of nuclear spin) which must replace the two wave-functions necessary to describe the electron spin fine structure. In order to describe the multiple energy levels correctly we must calculate the interaction energy of the two spins in addition to the energy increments already calculated in I and II. This is the first purpose of the present paper, and the work is carried out for the cases i n = ½, 1, 1½, 4½. It is found that in the case of the p ½ levels the interaction energy of the two spins is equal to that of the nuclear spin and orbital momentum, while for the p 3/2 levels the ratio is — ⅕. It is further found that the energy levels of the S terms are correctly given in I and II. As regards comparison with Jackson’s results in the case of cæsium, it would seen that, the separation of the p -levels being very small in comparison with that of the S-level, he has been able to observe the multiplet structure of the lines due to the separation of the S-level only. If we make this assumption it will be seen on reference to I that our results agree quite well with his observations.

Brightness temperatures and intensity measurements in flash discharges

1961 ◽  
Vol 262 (1310) ◽  
pp. 409-419 ◽  
Keyword(s):  
Brightness Temperature ◽  
Wavelength Range ◽  
Intensity Distribution ◽  
Wave Number ◽  
Brightness Temperatures ◽  
Intensity Measurements ◽  
Capillary Type ◽  
Standard Lamp ◽  
The Continuum

The brightness temperature and the intensity distribution of the Lyman, coaxial and capillary-type flash tubes have been measured and compared over the wavelength range from 2580 to 4520 Å. The brightness temperature, obtained by comparison with a standard lamp, for these flash tubes ranged from 13 000 to 30 000 °K. The intensity per unit wave number was found to be independent of wave number over the above range for the Lyman and coaxial tubes. For the capillary flash the region independent of wave number extended up to 31 000 cm -1 beyond which the continuum decreased exponentially, in agreement with the predictions of the Unsöld-Kramers theory.

Sign in / Sign up

Export Citation Format

Share Document