scholarly journals The spectra of the halogen molecules. Part I.-Iodine

1933 ◽  
Vol 141 (845) ◽  
pp. 603-625 ◽  
Keyword(s):  
Emission Spectrum ◽  
Intensity Distribution ◽  
Wave Length ◽  
The Other ◽  
Comparable Data ◽  
General Survey ◽  
Band Spectra ◽  
Low Dispersion ◽  
Existing Data

The term “halogen molecule” is intended to include the interhalide compounds as well as the elementary molecules. The existence of three of the ten possible molecules of this type, namely, IF, BrF, and CIF, has not yet been established, and we have not attempted any spectroscopic search for them. For F 2 the data are meagre, only an emission spectrum being known, and we have therefore confined our attention to the other six molecules, namely, CI 2 , Br 2 , I 2 , BrCl, ICI, and IBr. The spectra of these, with the exception of BrCl, have been extensively investigated, and partially interpreted. There are certain features, however, notably the continua and diffuse bands observed in emission, which have not yet been satisfactorily explained, and we have set out to survey the existing data systematically and, where necessary, to obtain new data with the object of accounting for these features. The problem of obtaining satisfactory data of continua and diffuse bands is definitely different from that involved in the case of line and ordinary band spectra. Not only is it more difficult to make accurate visual settings for the purpose of wave-length determinations, but it becomes of much more importance to record the intensity distribution, which is often very characteristic and undoubtedly significant. For these reasons we have thought it essential to obtain and reproduce microphotometer records in all experiments, and to determine wave-lengths solely from these records. Quite low dispersion has been used, and appears very suitable for a general survey, although a more detailed investigation using higher dispersion may well prove profitable later. It seemed important to us to get strictly comparable data in all observations, and it has therefore been necessary to redetermine some of the existing data, which although numerous are seldom complete or homogeneous. A number of entirely new data are also presented. Some consideration must first be given to the known band systems of these molecules, since they provide evidence relating to the location and characteristics of molecular levels, some at least of which may be expected to be concerned in the emission of the continua and diffuse bands.

scholarly journals Interferential comparison of the red and other radiations emitted by a new cadmium lamp and the michelson lamp

1933 ◽  
Vol 139 (837) ◽  
pp. 202-218 ◽  
Keyword(s):  
Fine Structure ◽  
High Temperature ◽  
Wave Length ◽  
The Other ◽  
Reference Standard ◽  
Definite Evidence ◽  
Electro Magnetic ◽  
The Many ◽  
Red Radiation ◽  
Red Line

It is now generally recognised that future definitions of the units of length will probably be based on the length of a wave of visible light. At present the wave-length of the red radiation of cadmium serves as the basis of all measurements of the lengths of electro-magnetic waves which are perceptible by optical means, and provisional sanction has been given to measurements of length on the same basis, as an alternative to direct reference to the metre. Whether the cadmium red radiation provides the best reference standard for all measurements of length has not yet been definitely established. Two international committees, one representing spectroscopists and the other metrologists, have sanctioned standard specifications for cadmium lamps of the Michelson type from which the red radiation may be produced. The two specifications differ from one another in certain details, but both are subject to the same objections. These objections are directed partly against the high temperature at which it is necessary to run the lamp and partly against the high voltage required to excite the radiation. Therefore, such hyperfine structure and asymmetry as may be present in the red line of cadmium is likely to be masked in the Michelson lamp by a combination of two phenomena —the enhanced Doppler effect due to the high temperature of the radiating cadmium atoms, and the effect of the moderately high intensity of the electric field. Were this not so, it might be somewhat surprising that no definite evidence of fine structure or asymmetry had so far been observed in the red line from the Michelson lamp, notwithstanding the many careful examinations, with the aid of the most sensitive interferometers, to which this line has been subjected, in view of its importance as the reference standard for all other wave-lengths. Recently Nagaoka and Sugiura have recorded that they have observed slight evidences of structure in the red radiation when excited under special conditions in which great precautions were taken to ensure extreme sharpness of the line. It is believed, however, that no subsequent confirmation of this effect has yet been published.

scholarly journals The spectrum of thallium chloride

1938 ◽  
Vol 166 (925) ◽  
pp. 238-249 ◽  
Keyword(s):  
The Other ◽  
Electronic Transitions ◽  
Sufficient Information ◽  
Thallium Chloride ◽  
Band Spectra ◽  
Vibrational Constants

The results of a study of the spectrum of thallium fluoride (TIF) which have already been published (Howell 1937) contained so many points of unusual interest that it was considered desirable to extend the investigation to the other halides of thallium. In particular it was hoped to acquire sufficient information concerning the electronic transitions in TICI to enable a comparison to be made of the electronic levels of this molecule with those of TIF. Furthermore, certain of the vibrational constants of TICI, as listed in such reference works as Jevons' "Report on Band Spectra" (1932) and Sponer’s "Molekülspektren" (1936) seemed so abnormal as to justify a re-examination of this spectrum.

An experimental investigation of the nature and origin of microseisms at St. Louis, Missouri

1940 ◽  
Vol 30 (2) ◽  
pp. 139-178
Author(s):  
J. Emilio Ramirez
Keyword(s):  
Wave Length ◽  
Vertical Axis ◽  
The Other ◽  
Wave Form ◽  
Stationary Waves ◽  
Retrograde Motion ◽  
Time Signals ◽  
Group Form ◽  
Triangular Network ◽  
The Waves

Summary Over a period of six months, from July to December, 1938, an investigation on microseismic waves has been carried out in the Department of Geophysics of St. Louis University. Four electromagnetic seismographs, specially designed for recording microseisms, were installed in the city of St. Louis in the form of a triangular network. Two of these were E-W components, one at the St. Louis University Gymnasium and the other 6.4 km. due west at Washington University. The other two were arranged as N-S components, one at the St. Louis University Gymnasium and one 6.3 km. due south at Maryville College. The speed of the photographic paper was 60 mm/min., and time signals were recorded automatically and simultaneously on each paper from the same clock every minute and at shorter intervals from a special pendulum and “tickler” combination by means of telephone wires. The results have demonstrated beyond doubt that microseismic waves are traveling and not stationary waves. The same waves have been identified at each one of the stations of the network, and also at Florissant, 21.8 km. away from St. Louis University. The speed of microseismic waves at St. Louis was determined from several storms of microseisms and it was found to be 2.67±0.03 km/sec. The direction of microseisms was also established for most of the storms and it was found that about 80 per cent of incoming microseisms at St. Louis were from the northeast quadrant during the interval from July to December, 1938. No microseisms were recorded from the south, west, or southwest. The period of the waves varied between 3.5 and 7.5 sec. The average period was about 5.4 sec. The microseismic wave length was therefore of the order of 14¼ km. A study of the nature of microseismic waves from the three Galitzin-Wilip components of the Florissant station reveals in the waves many of the characteristics of the Rayleigh waves; that is, the particles in the passage of microseismic waves move in elliptical orbits of somewhat larger vertical axis and with retrograde motion. A comparison carried over a period of more than a year between microseisms and microbarometric oscillations recorded by specially designed microbarographs showed no direct relationship between the two phenomena in wave form, group form, period, or duration of storms. The source of microseisms is to be found not over the land, but rather out over the surface of the ocean. The amplitudes of microseisms depend only on the intensity and widespread character of barometric lows traveling over the ocean. Several correlations between the two phenomena seem to make this conclusion rather evident. Special emphasis is laid on the fact that all the determined directions of incoming microseisms at St. Louis point to a deep barometric low over the ocean. The period of microseisms seems to be a function of the distance between the station and the source of microseisms. The exact mechanism by which barometric lows over the ocean water result in the production of microseisms needs further investigation. Large microseisms have been produced without any indication of surf near the coasts, or with winds blowing from the land toward the ocean.

scholarly journals I. A wave-length comparator for standards of length: An instrument for fine measurement in wave-lengths of light. - With an appendix on the use of wave-length rulings as defining lines on standards of length

1911 ◽  
Vol 210 (459-470) ◽  
pp. 1-34
Keyword(s):  
Wave Length ◽  
The Other ◽  
Single Spectrum ◽  
Interference Band ◽  
Half Wave ◽  
Autocollimation Method ◽  
New Apparatus ◽  
Reference Spot ◽  
The Difference ◽  
Reflecting Surfaces

The following is a brief account of a new apparatus for fine measurement in wavelengths of light, designed primarily as a comparator for the measurement in wavelengths of the difference between a standard of length, either a line or an end measure bar—the Imperial Standard Yard, for instance—and any duplicate or similar bar proposed to be employed as a derived standard. The instrument is also, however, the most perfect instrument yet devised for measurement in wavelengths in general, and performs its functions so admirably as to render it highly desirable that a description should now be published concerning it. It has been constructed to the designs and under the supervision of the author for the Standards Department of the Board of Trade, and this account of it is communicated to the Royal Society with the permission of the President of the Board of Trade. The principle underlying the instrument is that of the author’s interferometer, which has also proved so successful in its application, in the interference dilatometer, to the determination of the thermal expansion of small bodies by the Fizeau method, and in the elasmometer, to the measurement of the elastic bending of a small plate or bar under a given weight applied at the centre. The essence of the interferometer is that homogeneous light, of a definite wave-length, corresponding to a single spectrum line—isolated with the aid of a constant-deviation prism from the spectrum derived from a cadmium or hydrogen Geissler tube, or a mercury lamp—is directed by an autocollimation method, ensuring identity of path of the incident and reflected rays, normally upon two absolutely plane surfaces, arranged close to each other, and nearly, but not absolutely, parallel; the two reflected rays give rise, by their interference, to rectilinear dark interference bands on a brilliantly illuminated background in the colour corresponding to the selected wave-length. In the instrument now described, one of these two reflecting surfaces concerned in the production of the interference bands is carried by, and moves absolutely with, one of the two microscopes employed to focus the fiducial marks, or "defining lines", determinative of the length of the standard, the other surface being absolutely fixed. The movement of either of the surfaces with respect to the other causes the interference bands to move, and the extent of the movement of the surface is equal to half the wave-length of the light employed for every interference band that moves past a reference mark carried by the fixed surface. The movement of the microscope parallel to itself and to the length of the standard bar is thus measured by counting the number of bands and the initial and final fractions of a band which are observed to pass the reference spot during the movement, and multiplying that number by the half wave-length of the light radiation used in the production of the bands. It is only necessary, therefore, in order to compare the lengths of two bars, (1) to place the bar of known length, say, the Imperial Standard Yard, under the two microscopes so that the two defining lines are adjusted in each case between the pair of parallel spider-lines carried by each of the micrometer eye-pieces; (2) to replace the standard by the copy to be tested, so that the defining line near one end is similarly adjusted under the corresponding microscope, then, if the other defining mark is not also automatically adjusted under the second microscope which carries the interferometer glass surface, as it should be if it is an exact copy, (3) to traverse that microscope until it is so adjusted, and (4) to observe and count the number of interference bands which move past the reference spot during the process. The product of this number into the half wave-length of the light used to produce the bands thus obviously affords the difference between the two lengths included between the defining marks on the two bars.

scholarly journals Supersonic dispersion in gases

1934 ◽  
Vol 146 (856) ◽  
pp. 56-71 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Experimental Work ◽  
High Frequency ◽  
Response Curve ◽  
Wave Length ◽  
Soap Film ◽  
The Other ◽  
Rapid Degradation ◽  
Compressional Waves ◽  
Point Electrode

The rapid degradation of intensity suffered by compressional waves of high frequency in gases was first observed by pierce in carbon dioxide for frequencies in the neighbourhood of 2.10 5 cycles/sec. Although in the last few years a considerable number of measurements of the velocity of supersonic waves have been made, less experimental work has been done on the absorption . This present paper describes some work aimed at elucidating the mechanism of the phenomenon. Consideration was first given to the establishment of a source of vibrations of the requisite frequency. The possible apparatus reduces itself to four types: (1) edge-tones, (2) electric sparks, (3) small resonators of gas, (4) solid resonators; both of the latter types to be maintained by oscillating circuits incorporating valves. The frequency of an edge-tone depends directly on the velocity of the blast, and inversely on the distance from the blower to the edge, so that it should be possible to produce supersonic waves by making the former very large and the latter very small; in fact, Hartmann has already used such a source. The difficulty of maintaining constant blast velocity and the complications which the blast introduces in the propagation of such waves would, however, have made such a source unmanageable in the present work. Nekle-pajev has used sparks as sources in the examination of the absorption in air. But here again the frequency is difficult to measure or to maintain constant. Some success was obtained by the author with gaseous resonators consisting of short brass tubes terminated at one end by a brass stopper, and at the other end by a soap film, the distance between the two being half the wave-length at the frequency of excitation. The resonator was maintained in vibration by a valve oscillator, of which the plate was connected to a point electrode just above the soap film, while the grid was connected to the brass tube itself. Response of the resonator due to electrostatic attraction of the film was observed by the image of a glowing filament reflected from the slightly concave film on to a scale. By varying the tuning of the oscillator the response curve of the little resonator could be obtained.

scholarly journals Isotope shift in the resonance line of magnesium

1936 ◽  
Vol 154 (883) ◽  
pp. 679-683 ◽  
Keyword(s):  
Emission Line ◽  
Hyperfine Structure ◽  
Atomic Beam ◽  
Resonance Line ◽  
Isotope Shift ◽  
Wave Length ◽  
Spectral Lines ◽  
The Other ◽  
Absorption Lines ◽  
Doppler Width

By making use of an atomic beam instead of an ordinary gas or vapour, it is possible to observe structures of spectral lines very much smaller than the normal Doppler width. The structure of resonance lines can thus be observed as fine absorption lines on the background of the emission line possessing the full Doppler width. This method was used by the present authors for the detection and measurement of the hyperfine structure of the resonance lines of potassium and sodium. The following paper gives an account of the investigation of the structure of the singlet resonance line (2852 A) of magnesium by the same method. The line was found to possess two components at a separation of 0.033 cm -1 , the component of longer wave-length being very much stronger than the other.

The analysis of molybdates and tungstates

1966 ◽  
Vol 35 (275) ◽  
pp. 995-1002 ◽  
Author(s):  
A. J. Easton ◽  
A. A. Moss
Keyword(s):  
Optical Density ◽  
Wave Length ◽  
Ultra Violet ◽  
The Other ◽  
The Common ◽  
Significant Interference ◽  
And Tungsten

SummaryThe estimation of molybdenum and tungsten when present together has proved difficult, as is indicated by the large number of methods put forward for their determination. Many of the methods given are for one or other of these elements only, a note often being added that the presence of the other invalidates the method. The estimation of molybdate and tungstate in the mineral powellite has been briefly described by one of the authors (A. A. M.): molybdate and tungstate were precipitated as oxinates (Mo,W)O2(C9H6ON)2 and the molybdate (MoO4″) determined by measurement of the optical density at 230 mµ of a solution containing molybdate and tungstate. The amount of tungstate present was then estimated by difference. The property of the molybdate ion, MoO4″, to absorb strongly in the ultra-violet has been further investigated and it has been found that, if a wave-length of 240 mµ is chosen and the proper precautions taken, the MoO4″ ion can be estimated without significant interference by the WO4″ ion. Methods are given for the analysis of the common molybdate and tungstate minerals, together with results obtained during the course of this investigation.

The orientation behaviour of multiple chromosome configurations in acridid grasshoppers

Genome ◽  
1987 ◽  
Vol 29 (2) ◽  
pp. 292-308 ◽  
Author(s):  
B. John
Keyword(s):  
Key Words ◽  
Reciprocal Translocation ◽  
Chiasma Frequency ◽  
The Other ◽  
Robertsonian Fusion ◽  
Orientation Behaviour ◽  
Chiasma Distribution ◽  
First Time ◽  
Existing Data ◽  
Combined Data

The existing data on the behaviour of multiple chromosome configurations arising from single interchanges between either metacentric–telocentric or telocentric–telocentric nonhomologues in 10 species of acridid grasshoppers are compared with data from four new cases. Two of these new cases involve metacentric–telocentric exchanges but the other two, for the first time in acridids, deal with a reciprocal translocation between two nonhomologous metacentrics. The combined data are used to evaluate the factors that influence multiple orientation in this family of grasshoppers and reemphasize the importance of chiasma frequency and chiasma distribution for multiple behaviour. This conclusion is reinforced by a consideration of the known cases of chain of three multiples originating from the Robertsonian fusion of nonhomologous telocentrics in acridoids. Key words: acridid grasshoppers, multiple chromosome configurations, chiasma distribution, orientation behaviour.

THE EMISSION SPECTRUM OF ALUMINUM MONOFLUORIDE. II

1954 ◽  
Vol 32 (3) ◽  
pp. 246-258 ◽  
Author(s):  
S. M. Naudé ◽  
T. J. Hugo
Keyword(s):  
Emission Spectrum ◽  
Spectral Region ◽  
Single Band ◽  
The Other ◽  
Rotational Analysis ◽  
Infrared Spectral Region ◽  
Infrared Spectral

Four new band systems of the emission spectrum of AlF are described, viz. the DlΔ – A1II system in the yellow-green, the F1II – A1II and G1Σ – A1II systems in the blue, and the F1II – B1Σ system in the infrared spectral region. A vibrational as well as a rotational analysis of the D1Δ –A1II system is reported. The rotational analyses of the other systems, each of which consists of a single band, are described.

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