scholarly journals Further spectra associated with carbon

1925 ◽  
Vol 108 (746) ◽  
pp. 343-355 ◽  
Keyword(s):  
Visible Spectrum ◽  
Ultra Violet ◽  
Line Spectrum ◽  
Band Spectrum ◽  
Comet Tail ◽  
Experimental Conditions ◽  
Negative Band ◽  
In Series ◽  
Condensed Discharge ◽  
Band Spectra

In a recent paper by Professor Merton and myself, an investigation was made of the experimental conditions effecting the isolation of some familiar band-spectra of Carbon. In particular, we made a study of the action of Helium in isolating and modifying spectra associated with this element. It was found that under appropriate conditions some new spectra of Carbon were isolated. With a trace of an oxide of Carbon in some 20 to 30 mm. of Helium an uncondensed discharge produced a band system identical with that found by Pluvinet and Baldet in the spectrum of comet tails, and which was afterwards discovered by Fowler to be characteristic of CO at extreme low pressures. Tubes prepared in this way and subjected to a mild condensed discharge yielded a spectrum consisting only of the lines and bands of Helium, and a number of new lines which were attributed to Carbon. A notable feature of the latter spectrum was the bright line at λ 5380, recorded previously only as a Carbon line of small intensity. The characteristic spark lines λλ 6583, 6578, 4267, were also absent, or of very doubtful occurrence, and the conditions of excitation led us to suggest that this line spectrum might be the true “arc” spectrum of Carbon, which the energy of the ordinary arc was insufficient to produce, and that of the condensed spark sufficient to repress. Both the line-spectrum and the Comet-Tail bands were investigated only in the visible spectrum; in the present paper observations and measurements of these spectra in the ultra-violet are recorded. In addition, a new band-spectrum apparently associated with the Comet-Tail bands has been measured and expressed by a series formula. The opportunity afforded by the exceptionally strong development of the first negative band-spectrum of Carbon has been taken to re-measure these bands and dispose them in series. Finally, the significance of some of these phenomena is discussed.

scholarly journals Ultra-violet emission bands associated with oxygen

1924 ◽  
Vol 105 (734) ◽  
pp. 683-691 ◽  
Keyword(s):  
Wave Length ◽  
Negative Electrode ◽  
Ultra Violet ◽  
Pure Oxygen ◽  
High Dispersion ◽  
Band Spectrum ◽  
Absorption Bands ◽  
Violet Emission ◽  
Negative Band ◽  
Band Spectra

Of emission band spectra generally attributed to oxygen the best known is the negative band spectrum with four strong heads at λλ6420-6300; λλ6010- 5960; λλ5630-5550; λλ5290-5200. In addition there are several other fainter bands about λλ5900-5840; λλ6790-6700; λ6200; λ4980, etc. This spectrum appears with considerable intensity in the yellowish-white glow surrounding the negative electrode of a discharge tube containing pure oxygen, while at lower pressures it is visible along the capillary of the tube. The diffuse character of the bands under the dispersion of an ordinary prism spectrograph renders such wave-length determinations of little value however, except as serving for identification of the bands, and they do not appear to have been measured under high dispersion. The spectrum has been investigated by numerous observers, and although it has not been found in absorption there is general agreement that it arises from an oxygen molecule. In the far ultra-violet (λλ1830-1920) Schumann, using a fluorite spectrograph, was the first to obtain emission and absorption bands of oxygen. These bands were investigated in some detail by Steubing ( loc. cit. ), who confirmed Schumann's observations and showed that the system consists of some five bands extending from λλ1831—1845; λλ1848—1863; λλ1864—1881; λλ1882—1899; λλ1900-1919. Each head consists of about eleven lines giving the appearance of being degraded to the red; and the most refrangible head is the strongest of the five. He was also able to excite in this region the fluorescence spectrum of oxygen. It was found to coincide in position with the emission bands, though the intensity distribution in the spectrum was somewhat different. The two less refrangible heads, it should be mentioned, were observed in fluorescence only. The bands were attributed by him to an O 2 molecule and this appears to have been accepted by later workers; though Kayser took exception to these views.

scholarly journals The origin of the “cyanogen” bands

1920 ◽  
Vol 98 (688) ◽  
pp. 40-49 ◽  
Keyword(s):  
Band Spectrum ◽  
Positive Group ◽  
Positive Band ◽  
Negative Band ◽  
Spark Discharges ◽  
Carbon Arc ◽  
Vacuum Tubes ◽  
Band Spectra ◽  
Oxygen Complexes

There are, in addition to the line and the positive and negative band spectra of nitrogen, several other series of bands, in the production of which this element plays some part. The emission centres responsible for these bands have generally been identified with the molecules of compounds of nitrogen with other elements, though these molecules are not necessarily those of compounds which can be isolated under normal circumstances, and possibly may prove to be more of the nature of temporary associations. Such spectra include the so-called third positive band spectrum of nitrogen, the various spectra attributed to ammonia or other nitrogen-oxygen complexes, and also the cyanogen bands. The NO bands, Deslandres’ third positive group of nitrogen bands, are found in vacuum tubes filled with nitrogen, when they contain a trace of oxygen as impurity. They have also been observed in the carbon arc surrounded by a magnesia block, in uncondensed spark discharges in air and nitrogen, and in the flames of cyanogen and ammonia. They were formerly believed to be due to nitrogen alone, but Deslandres, Schniederjost, Lewis and others have proved that their production is dependent upon the presence of oxygen.

scholarly journals The spectrum of H 2 : The bands analogous to the ortho-helium line spectrum

1929 ◽  
Vol 122 (790) ◽  
pp. 688-718 ◽  
Keyword(s):  
Preliminary Investigation ◽  
Rotational Quantum Number ◽  
Principal Series ◽  
Visible Spectrum ◽  
Ultra Violet ◽  
Line Spectrum ◽  
Final States ◽  
Combination Principle ◽  
S States

In “Structure in the Secondary Spectrum of Hydrogen—Part V” it was shown that there existed in this spectrum a very extensive series of bands whose null lines were related by a Rydberg-Ritz formula and whose electronic terms were very close to those of the principal series of the so-called helium doublets (orthohelium) showing that the spectrum of H 2 is closely analogous to the line spectrum of He. [It is also very similar to the spectrum of He 2 .] This similarity has since been confirmed by the discovery and investigation of the absorption spectrum of unexcited H 2 by Dieke and Hopfield from which it appears that none of the final 2 states of that spectrum, in which the transitions are from 1 1 S to an upper 2 state, are the same as the final 2 states of these emission bands. On the other hand their 2 1 S states do agree, to the accuracy of the ultra-violet data, with the final states of an entirely different set of band systems in the visible spectrum which are therefore analogous to the parhelium spectrum. The conclusions of Part V were drawn from a study of the Q branches of the bands only. In an earlier paper (Part IV) a preliminary investigation of some of the accompanying P and R branches had been made by a study of the intensity distribution in these bands in the first type discharge. This method enables the lowest rotational quantum number lines of the bands to be picked out with some certainty but the upper lines cannot in general be recognised on account of the faintness of the discharges. These can only be located by finding lines which satisfy some reasonable combination principle. An attempt made by one of us (O. W. R.) in collaboration with Dr. D. B. Deodhar to extend the classification of Part IV led us to the conclusion that the existing data were inadequate, mainly owing to insufficient resolution, to enable a satisfactory decision to be formed as to whether the details of Part IV were correct or ought to be modified.

scholarly journals The band spectrum associated with helium

1915 ◽  
Vol 91 (631) ◽  
pp. 432-439
Keyword(s):  
Principal Series ◽  
Universal Constant ◽  
Band Spectrum ◽  
Wave Numbers ◽  
In Series ◽  
Limiting Behaviour ◽  
The Difference ◽  
Band Spectra ◽  
Regular Manner ◽  
Significant Addition

A very significant addition to our knowledge of the nature of band spectra has been made by Prof. Fowler, who has lately described the results of his examination of the band spectrum found in connection with helium and hydrogen, and believed to be a spectrum of helium. For Halm has maintained that the formulæ which must be used to represent line and band spectra are intimately associated, and, in fact, spectroscopists have been generally inclined to suspect that the laws of line spectra have some counter-part in band spectra also. Fowler has taken the first step in the elucidation of this connection by showing that the universal constant of Rydberg belongs to this individual band spectrum, which contains two series of double "heads" arranged essentially in the same manner as the lines in a series spectrum. One feature, however, of these double "heads" or doublets appears at first sight to differentiate them from the doublets found in line spectra, and one purpose of this paper is to show that the difference in character is only apparent, and that the formal analogy with line spectra extends very far. In ordinary Diffuse or Sharp series of doublets, the intervals between the components, when expressed in wave numbers, are constant, whereas in a Principal series the intervals rapidly become smaller, and vanish at the limit of the series. The intervals decrease, moreover, in a very regular manner. In the band-doublets discussed by Fowler, although the intervals decrease as the series proceed towards their limits, the decrease is not very regular, as shown by the differences, and the intervals do not obviously vanish at the limits. Without a very precise arrangement in series, it is not possible to judge of their limiting behaviour.

scholarly journals Measurement of rotatory dispersive power in the visible and ultra-violet regions of the spectrum

1908 ◽  
Vol 81 (550) ◽  
pp. 472-474 ◽  
Keyword(s):  
Photographic Plate ◽  
Monochromatic Light ◽  
Green Light ◽  
Visible Spectrum ◽  
Ultra Violet ◽  
Narrow Strip ◽  
In Series ◽  
Limited Scale ◽  
Dispersive Power ◽  
Constant Deviation

The following is a brief preliminary account of improvements effected in the method of determining rotatory dispersive power which have made it possible to observe accurately not only in the bright regions of the visible spectrum, but throughout the scale from the region of the lithium red line into that commanded by the photographic plate. Two methods have generally been used for the purpose, namely, (1) Broch’s method, in which a spectroscope is arranged in series with the polarimeter and a narrow strip of a continuous spectrum is picked out for observation—a method which is much improved by using a constant-deviation spectroscope in place of one of the variable-deviation type, and .(2) Landolt’s method, in which a white light is reduced by means of filters to approximate homogeneity in the red, green, light-blue, or dark-blue parts of the spectrum. Neither method fulfils the fundamental condition that the field of the polarimeter shall be uniformly lighted with monochromatic light—many of the measurements that have been made, therefore, possess only a qualitative value. A much better method is due to the late Sir William Perkin, who introduced the use of a spectroscope-eyepiece as a means of purifying the sodium light, and used it on a limited scale for measuring rotatory dispersive power in the red (lithium), yellow (sodium), and green, thallium) parts of the spectrum.

scholarly journals Rotational analysis of the first negative band spectrum of oxygen

1938 ◽  
Vol 237 (783) ◽  
pp. 471-507 ◽  
Keyword(s):  
Hollow Cathode ◽  
High Frequency ◽  
Ultra Violet ◽  
Hollow Cathode Discharge ◽  
Rotational Structure ◽  
Band Spectrum ◽  
First Order ◽  
Negative Band ◽  
Quantum Numbers ◽  
Low Dispersion

The first negative bands of oxygen, A 6856, (0, 2), A 6419, (0, 1), A6026, (0, 0), A 5632, (1, 0) and A 5295, (2, 0) appear in the negative glow when a discharge is passed through oxygen at low pressure. Under low dispersion the bands appear very diffuse, but each exhibits on the long-wave side a well-defined head degraded to the violet, to which the wave-lengths given above refer, accompanied by a less well-defined head about 30 cm.-1 towards shorter wave-lengths. Though they have no state in common with the ultra-violet negative bands they are generally attributed to the O j molecule. References to earlier work are given by Frerichs (1926), who excited the spectrum with high intensity in a hollow-cathode discharge in oxygen and photographed it in the first order of a 21 ft. grating. In each band he found two branches, one of which formed the sharp head referred to above. On the basis of a combination relation between the branches he assigned vibrational quantum numbers to the bands. Bands additional to those given above have been discovered by Mulliken and Stevens (1933) and Bozoky and Schmid (1935). It was found by the latter workers that the bands given above, with the exception of A6856, were not single but formed the first band in each of the progressions v' — v" = — 1, 0, +1, +2, respectively. They excited the spectrum by a high-frequency discharge which seemed to have a lower effective temperature than the hollow.-cathode discharge, so that the rotational structure was not well developed and the later bands in each progression were not masked by the overlapping rotational structure of the first band

scholarly journals The spectrum of ionised oxygen (O II)

1926 ◽  
Vol 110 (755) ◽  
pp. 476-501 ◽  
Keyword(s):  
Laboratory Experiments ◽  
Capillary Tube ◽  
Ultra Violet ◽  
Line Spectrum ◽  
Narrow Capillary ◽  
Points Of Interest ◽  
Condensed Discharge ◽  
Stellar Temperatures

Two different line spectra of oxygen have long been known under the names "compound line" elementary line” spectra, assigned by Schuster in 1879 on the supposition that complex and simplified molecules or “molcular groupings” were respectively involved in their production. The possibility of a further modification of the line spectrum was also foreshadowed by Schuster, in collaboration with Roscoe, in the observation of a line at λ 5592 when a condensed discharge was passed through oxygen in a short and narrow capillary tube. Additional lines of this third type were observed later by Lunt, and further investigated by Fowler and Brooksbank. In accordance with present views as to the origin of spectra, the three spectra are attributed to neutral, singly-ionised, and doubly-ionised atoms, are designated O I, O II, O III, or O, O + , O ++ . Other spectra representing higher degrees of ionisation are theoretically possible, and evidence of the production of O IV and O V in the spectra of vacuum sparks has been obtained by Millikan and Bowen. The first three spectra are of considerable interest to astrophysicists on account of their occurrence in stars of successively higher temperatures, in strict accordance with the results of laboratory experiments. Among other points of interest, the analysis of these spectra may eventually lead to trustworthy values of the successive ionisation potentials, and thence to important deductions as to stellar temperatures. This result, however, has only at present been finally attained with respect to O I, through the extension of the observations into the extreme ultra-violet by Hopfield.

scholarly journals The band spectrum of silicon monosulphide and its relation to the band spectra of similar molecules

1938 ◽  
Vol 169 (936) ◽  
pp. 45-65 ◽  
Keyword(s):  
Band System ◽  
Ground States ◽  
Ultra Violet ◽  
Group Iv ◽  
Band Spectrum ◽  
Positive System ◽  
System A ◽  
Band Spectra

In a recent paper (Jevons, Bashford and Briscoe 1937) on the ultraviolet band system of GeO, a survey was made of the band systems of the monoxides and monosulphides of the Group-IV(B) elements which appeared to be analogous to the “Fourth Positive” system (A 1 II -> x 1 Σ) of CO and the well-known ultra-violet systems of CS and SiO It was found that when the observed values of the vibrational coefficients w e and x e w e were plotted against the number of electrons in the molecule two pairs of uninflected curves were obtained for the lower states of the monoxides and monosulphides, these states being probably all 1 Σ ground states, and two similar pairs of curves were obtained for the upper states.

scholarly journals An improved method of ultra-violet anomalous rotary dispersion of sodium tartrate

1928 ◽  
Vol 119 (783) ◽  
pp. 706-709
Keyword(s):  
Wave Length ◽  
Visible Spectrum ◽  
Ultra Violet ◽  
Rotatory Power ◽  
Rotatory Dispersion ◽  
Improved Method ◽  
Sodium Tartrate ◽  
Approximate Form ◽  
Rotary Dispersion ◽  
In Series

A large number of ultra-violet polarimetric measurements have been made by a method described by one of us in 1908.* In this method a triple-field polarimeter, with Foucault in place of Nicol prisms, is arranged in series with a quartz or quartz-calcite spectrograph. A quartz-calcite lens, replacing the eyepiece of the polarimeter, casts a real image of the triple field on the slit of the spectrograph, and thus gives rise to a triply divided spectrum, intersected by dark bands. The wave-length corresponding with a given rotation is determined by finding a line which is of equal intensity in the three fields. The approximate form of the curve of rotatory dispersion can be determined by setting the analyser in a series of positions separated by 5° or 10° ; but it is then advisable to “bracket” some of the more conspicuous lines by making fresh exposures at intervals of perhaps 0·2°, when the rotation corresponding with the wave-length of a given line can be determined within about 0·1°. This degree of accuracy is less than that which can be reached in the central part of the visible spectrum, where the readings may be reproduced under favourable conditions within about 0·01° ; but it is not appreciably less than the accuracy of visual readings in the red and violet regions, and for many purposes is quite satisfactory. Thus, with a column of quartz 496 mm. in length, readings to 1° sufficed to give the rotatory power in degrees per milli­metre within 0·002°, corresponding with an error of about 1 part in 100,000 at wave-length 2327. The present investigation was undertaken in order to find out whether the same apparatus could be used to record with sufficient accuracy the much smaller rotations of solutions which had been largely diluted, in order to render them transparent in a region near to (or covered by) an absorption band. For this purpose the concentration is often reduced to I per cent. : the observed rotations may then be of the order of 0·5°, and must be read to 0·01° or less in order to give a true impression of the form of the curve of rotatory dispersion.

scholarly journals On experiments relating to the spectrum of nitrogen

1925 ◽  
Vol 107 (743) ◽  
pp. 411-422 ◽  
Keyword(s):  
Nitrogen Atom ◽  
Atmospheric Pressure ◽  
Negative Band ◽  
Discharge Tubes ◽  
In Series ◽  
Striking Change ◽  
The Subject ◽  
Band Spectra ◽  
Low Pressures ◽  
Conventional Type

It is somewhat remarkable that the spectrum of the neutral nitrogen atom, nitrogen arc or NI spectrum, should be the least known of the spectra associated with nitrogen. The positive and negative band spectra, associated with nitrogen molecules, have been the subject of many investigations, and the line spectra which are developed when condensed discharges are passed rough nitrogen at atmospheric pressure or through nitrogen contained in ancuum tubes, the spectrum of singly ionised nitrogen, the NII spectrum, has recently been arranged in series by Fowler ( ‘Roy. Soc. Proc.,' vol. 107, A, p. 31,25), who has in an earlier investigation (‘Monthly Notices R. A. S.,’ vol. 80, 692, 1920) assigned a number of lines which have not yet been arranged in series to the doubly ionised nitrogen atom. It would appear that under ordinary conditions of excitation the lines of the arc or nitrogen I spectrum are not conspicuous, and we are indebted to Hardtke (‘Ann. der Phys.,’ vol. 3, p. 363, 1918) for the information at present available with respect to this Spectrum. Hardtke found that with discharge tubes of special construction containing nitrogen a number of lines were predominant in the spectrum of the positive rays observed in certain regions of the discharge tubes, and that the same lines were relatively enhanced in vacuum tubes of the conventional type when they were excited by condensed discharges of feeble moderate intensities. Hardtke gave approximate measurements of a Number of these lines, which he assigned to the arc spectrum. In a series of previous investigations (Merton, ‘ Roy. Soc. Proc.,’ A, vol. 96, 382, 1920; Merton and Barratt, ‘ Phil. Trans.,’ A, vol. 222, p. 369, 1922; Merton and Johnson, ‘ Roy. Soc. Proc.,’ A, vol. 103. p. 383, 1923) it has been Shown that profound modifications are sometimes observed in the spectrum of a substance when a very small quantity of that substance is present in a discharge tube containing helium at a comparatively high pressure, and the tube is excited by condensed or uncondensed discharges. Thus with uncondensed discharges there is a striking change in the distribution of intensity the lines of the secondary spectrum of hydrogen; a trace of carbon is recognised by the appearance of the ‘‘comet tail” spectrum, first observed by Fowler (‘Monthly Notices R. A. S.,’ vol. 70, p. 484, 1910) at very low pressures and when both carbon and hydrogen are present a new triplet series of band: are developed.

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