scholarly journals The structure of the molecule of nitrogen dioxide from a study of its infra-red absorption spectrum

1934 ◽  
Vol 145 (854) ◽  
pp. 278-287 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Absorption Band ◽  
Carbon Disulphide ◽  
High Dispersion ◽  
Detailed Knowledge ◽  
Absorption Bands ◽  
Nitrogen Tetroxide ◽  
Triangular Form ◽  
Infra Red ◽  
A Cell

In a previous paper, which gave an account of work on the infra-red absorption spectrum of nitrogen tetroxide there was necessarily included a preliminary survey of the spectrum of the dioxide, but no detailed description was given of the absorption bands, nor was any attempt made to deduce the structure of this molecule. Since that paper was communicated several other investigators have published accounts of work on the infra-red and electronic spectra of these two molecules and conflicting views have been expressed regarding the structure of the dioxide molecule. Bailey and Cassie ( loc. cit. ) have favoured a liner symmetrical structure resembling that of carbon dioxide or carbon disulphide, while Harris, Benedict and King and also Schaffert ( loc. cit. ) have contended that the form of the molecule is triangular with the nitrogen atom at the apex of an isosceles triangle. None of these workers report having examined any of the infra-red bands under high dispersion, although the contours of two of the strongest of the dioxide bands were reported by Bailey and Cassie. Yet a detailed knowledge of any possible fine structure in the strongest bands and of the contours of at least some of the weaker bands is of supreme importance in deciding the structure of the molecule. The purpose of the present paper is to give an account of the examination of the infra-red spectrum of the dioxide under high dispersion and from a critical discussion of the present date to show that all the evidence is in favour of this molecule having a triangular form. Experimental . For details of the experimental procedure the reader is referred to the earlier paper on nitrogen tetroxide and Table I contains a list of the observed bands as there given. Since the examination of the absorption beyond 1450 cm. -1 was done using a cell with rock-salt windows, it was not possible at that time to decide whether the absorption near 1350 cm. -1 was a true absorption band of NO 2 or whether it was due to the sodium nitrite which formed on the windows of the cell. The work of Schaffert ( loc. cit. ) in which a cell with very thin mica windows was used proves beyond doubt that there is an absorption band of NO 2 at 1373 cm. -1 . Again our observations were confined to wave-lengths less than 14 μ so we did not observe the absorption, which has also been confirmed by Schaffert ( loc. cit. ), reported by Bailey and Cassie ( loc. cit. ) at 15⋅6 μ (641 cm. -1 ).

scholarly journals The infra-red absorption spectrum of nitrogen tetroxide and the structure of the molecule

1933 ◽  
Vol 141 (844) ◽  
pp. 342-362 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Rock Salt ◽  
Research Work ◽  
The Other ◽  
Resolving Power ◽  
Absorption Cell ◽  
Nitrogen Tetroxide ◽  
Degree Of Dissociation ◽  
Infra Red ◽  
The Individual

The earliest observations on the infra-red absorption spectrum of nitrogen peroxide were made by Warburg and Leithauser, who found that at ordinary temperatures the mixture of the tetroxide and dioxide had strong absorption maxima at 3•4 μ, 5•7μ, and 6•1μ. By varying the temperature, and so the degree of dissociation of tetroxide molecules into dioxide molecules, they were able to attribute the absorption band at 5•7μ, to the nitrogen tetroxide molecule, and show that the other two bands were due to the molecule of nitrogen dioxide. A later investigation by Eva von Bahr confirmed these observations and disclosed another band due to the dioxide at 7•3μ. None of these investigators examined the region beyond 8 μ, and all the work was done using low dispersion. Recently Strong and Woo have examined the spectrum between 23 μ, and 150 μ, and find two main regions of absorption, one near 26 μ and 150 μ and the other around 80 μ. Experimental. The spectrometer used in the first survey of the spectrum was a prism instru­ment having a 60° rock salt prism in the Wadsworth mounting. Subsequently several of the bands were examined on grating instruments of high resolving power. The absorption cell used in the preliminary work was of brass, 20 cm. in length, and with rock salt windows. This cell was lagged with asbestos and could be heated electrically until the temperature of the gas which it contained was as high as 160° C. The absorption cell used in the examination of the individual bands was of glass, 10 cm. long, and with mica windows. For work in the region beyond 7 μ. the mica windows were replaced by ones of rock salt. The nitrogen peroxide was taken from a very pure sample specially prepared for research work. It was kept in a sealed pyrex tube as a liquid (under its own pressure) and the gas was transferred to the cells as required, drying tubes containing phosphorus pentoxide being used to avoid con­tamination from water vapour in the atmosphere.

scholarly journals Investigations in the infra-red region of the spectrum. Part V.— The absorption spectrum of carbonyl sulphide

1932 ◽  
Vol 135 (827) ◽  
pp. 375-391 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Absorption Spectrum ◽  
Carbon Disulphide ◽  
Linear Structure ◽  
Potassium Thiocyanate ◽  
Gaseous Product ◽  
Infra Red ◽  
Glass Seals ◽  
Carbonyl Sulphide

The symmetrical linear structure of both carbon dioxide and carbon disulphide is now well established. Recent developments in theory make it highly probable that a complete explanation of the Raman and infra-red spectra of these substances, with the concomitant selection rules, will shortly be available. It is in the meantime of consequence to examine the absorption spectrum of carbonyl sulphide, since the chemical and external physical properties of this molecule are intermediate to those of the other two, though the lack of symmetry in its structure predicts more complex intramolecular relationships. No previous determination of this spectrum appears to have been made. Experimental . Carbonyl sulphide was prepared by dropping sulphuric acid (5 parts of acid to 4 of water by volume) on to potassium thiocyanate in a flask maintained at 21° C. by means of a water bath. The chief impurities generated in the reaction are carbon disulphide, carbon dioxide, and carbon monoxide* ; the gaseous product was led firstly through a trap immersed in a freezing mixture of salt and ice, secondly through a bubbler containing a 33 per cent, solution of potassium hydroxide, thirdly through a tube of active charcoal, fourthly through calcium chloride, and finally, through a trap immersed in a saturated solution of carbon dioxide snow in acetone, to the fume cupboard v en t; glass to glass seals were used throughout. The traps and tubes removed in succession the major portion of the carbon disulphide, the carbon dioxide, the remaining carbon disulphide, and the water vapour ; carbonyl sulphide boils at —50° C. and was condensed in the last trap at a temperature of —78°, any carbon monoxide passing on unabsorbed. When sufficient of the required substance had been collected, the trap was disconnected from the generating apparatus and connected to the absorption tube system, where the gas was transferred to an evacuated aspirator and stored over phosphoric oxide. The aspirator was totally enclosed to obviate possible decomposition of the carbonyl sulphide by light.

Ultra-violet and infra-red investigations on muscle

1950 ◽  
Vol 137 (886) ◽  
pp. 80-87 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Visible Region ◽  
Ultra Violet ◽  
Muscle Fibres ◽  
Absorption Bands ◽  
Important Region ◽  
Infra Red ◽  
New Type ◽  
Single Fibres ◽  
Red Radiation

Infra-red absorption spectroscopy of muscle has already been carried out, using the Burch reflecting microscope (Barer, Cole & Thompson 1949: Barer, Thompson & Williams unpublished). There are considerable difficulties involved in this type of work. In the first place it is rather doubtful whether such measurements will ever be possible on living muscle owing to the presence of water, which possesses intense absorption bands in some of the most useful regions of the infra-red spectrum. It may be possible to overcome this difficulty to some extent by using heavy water which has a different absorption spectrum. It is in principle possible to obtain information similar to that given by infra-red spectroscopy, even in the presence of water, by means of Raman spectroscopy, but the technical difficulties involved, particularly fight scattering by colloids, would seem to preclude this method of attack so far as muscle is concerned. Our infra-red measurements have hitherto been confined to dried material. The results indicate that there is little prospect of working with whole muscles, as even single isolated striated fibres of the frog, rabbit and crab were usually too thick. However, it was possible to obtain good spectra in the chemically important region from 3 to 14/ µ on exceptionally thin single fibres or on artificially compressed fibres. An attempt was made to detect dichroism by means of polarized infra-red radiation, but to our surprise none was observed throughout the 3 to 14 µ range, even though the material used showed strong birefringence in the visible region. Hr Stocken and I have recently examined certain molecular models of muscle, in the fight of the work of Ambrose, Elliott & Temple (1949) on myosin, and it now appears possible that infra-red dichroism of muscle might be expected to manifest itself only under rather special conditions. We hope to put these theoretical deductions to experimental test. As regards measurements on muscle in the ultra-violet region, the position is much more promising. It is quite possible to determine the absorption spectrum of the A or I band in living single fibres. The entire spectrum from about 230 m µ in the ultra-violet to over 600 m µ , in the visible can be recorded simultaneously, using the reflecting microscope. This technique can also be used with polarized ultra-violet fight, in order to detect variation of dichroism in crystals at different wave-lengths (Barer, Jope & Perutz unpublished), and I intend to apply it to the study of dichroism in muscle fibres. Another new possibility is the observation of birefringence, as well as dichroism, in the ultra-violet. I have recently carried out experiments with a view to developing a new type of ultra-violet polarizer and it should now be possible to use the reflecting microscope as an ultra-violet polarizing microscope.

scholarly journals Investigations in the infra-red region of the spectrum. Part X.―The asymmetrical molecule nitrosyl chloride, NOCl

1934 ◽  
Vol 145 (854) ◽  
pp. 336-344 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Experimental Fact ◽  
Nitrosyl Chloride ◽  
Characteristic P ◽  
Absorption Bands ◽  
Vertical Angle ◽  
Force System ◽  
Valence Force ◽  
Infra Red

The infra-red absorption spectrum of nitrosyl chloride was investigated with two objects in view. Firstly, if the substance is a covalent compound with normal valency linkings, the molecule will probably be asymmetrical and triangular. If this is so, the absorption bands will show no pronounced branch maxima such as are predicted and observed for symmetrical molecules, and the presence or absence of these maxima in the same conditions of resolution and concentration provides a test of the theory according to which the spectra of such gases as SO 2 , ClO 2 , and Cl 2 O have been interpreted. The two former molecules are required by the theory to be symmetrical, although such symmetry is not to be expected from the ordinary rules of valence. The experimental fact that the characteristic P, Q, and R branch maxima are absent in NOCl thus provides a verification of the theory. Secondly, six electrons are effectively available for binding in the molecule, and accordingly the structure should be triangular with a vertical angle ONCl approximately 120°, and governed by a valence force system. The molecule should, therefore, show whether or not the structure of triatomics is determined primarily by the number of available binding electrons.

Electronic spectra of salts of dithiocarbamic acids

1979 ◽  
Vol 44 (8) ◽  
pp. 2487-2493 ◽  
Author(s):  
Drahomír Oktavec ◽  
Jozef Štefanec ◽  
Bohumil Síleš ◽  
Václav Konečný ◽  
Ján Garaj
Keyword(s):  
Absorption Band ◽  
Electronic Spectra ◽  
Alkyl Chain ◽  
Carbon Disulphide ◽  
Blue Shift ◽  
Uv Spectra ◽  
Red Shift ◽  
Ammonium Salts ◽  
Absorption Bands

The report gives synthesis and UV spectra of a series of alkali and ammonium salts of the dithiocarbamic acids derived from dimethyl-, diethyl-, dipropyl-, dibutyl-, dipentyl-, dihexyl-, diheptyl-, dioctyl-, diisopropyl-, diisobutyl-, methylisopropylamine, piperidine, morpholine, piperazine and pyrrolidine. The absorption bands due to transitions localized in the groups CSS (λmax ~ 260 nm) and NCS (λmax ~ 280 nm) show a red shift with increasing length of the alkyl chain. Increasing polarity of solvent causes, with some of the compounds, a small red shift of λmax of the band due to CSS group, but it causes a considerable blue shift of λmax of the band due to NCS group in all the studied compounds. The absorption band near 207 nm is ascribed to the carbon disulphide produced by decomposition of the dithiocarbamates.

scholarly journals Absorption bands of HCN in the photographic infra-red

1934 ◽  
Vol 147 (862) ◽  
pp. 434-442 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Line Width ◽  
Vibrational Energy ◽  
Pressure Effect ◽  
The Sun ◽  
Absorption Bands ◽  
Infra Red ◽  
Tungsten Lamp

The infra-red absorption spectrum of HCN has previously been investigated photographically by Badger and Binder. Since their publication, plates have been available which are sensitive much further into the infra-red. The most recent Agfa plates have their maximum of sensitivity at 10600 A and have been used by us as far as 12300 A with a tungsten lamp or even 12900 A with the sun. We have now used these plates to investigate the infra-red absorption spectrum of HCN up to 12300 A. While Badger and Binder found only two very weak bands at 7912 and 8563 A we have found two rather strong bands at 10385 A and 11645 A which could be accurately measured and analysed. In adition we have found an interesting pressure effect on the line width. The whole infra-red spectrum of this molecule and the vibrational energy scheme has recently been discussed by Adel and Barker who have also measured several new bands in the far infra-red.

scholarly journals The optical rotatory power of quartz on either side of an infra-red absorption band

1930 ◽  
Vol 127 (805) ◽  
pp. 271-278 ◽  
Keyword(s):  
Absorption Band ◽  
Characteristic Frequency ◽  
Ultra Violet ◽  
Rotatory Power ◽  
Experimental Result ◽  
Physical Optics ◽  
Alternative View ◽  
Absorption Bands ◽  
Infra Red ◽  
Optical Rotations

Drude’s equation for natural optical rotations depends on the existence of “ions” of characteristic frequency, of which each type contributes a partial rotation to the total rotatory power of the medium. There is nothing in the equation to limit the range of these frequencies, but in discussing the rotatory power of quartz (the only substance for which sufficient data were then avail­able), Drude himself concluded that “the kinds of ions whose natural periods lie in the infra-red are inactive” (‘Physical Optics,’ 1907, translation, p. 413). An alternative view was put forward by R. W. Wood, who concluded that a "spurious” anomaly could be produced in colourless media by the combined influence of an infra-red and an ultra-violet absorption band (‘Physical Optics,’ 1919 edition, p. 492); and C. E. Wood and Nicholas have applied the same theory in the hope of deducing the configuration of the molecule from the sign of an infra-red term of which the existence is not yet established by experiment. Experiments on these lines have, however, already been made by Ingersol, who found that the rotatory powers of a series of typical compounds decreased progressively in the infra-red region, right up to the limit of transparency of the medium. This experimental result is in agreement with the conclusions of Kuhn (private communication, of ‘Z. Phys. Chem.,’ B, vol. 4, p. 14 (1929), who anticipates that all rotations will diminish asympto­tically to zero in the infra-red; but it is directly opposed to the theoretical deductions of the authors cited above, whose diagrams represent the rotations as increasing asymptotically to ± ∞ on approaching a characteristic frequency in the infra-red. Moreover, since the rotatory powers of linonene and pinene decrease progressively, even when passing through a region which includes three absorption bands, it is clear that the phenomenon discovered by Cotton in coloured organic compounds is not reproduced in these infra-red bands.

scholarly journals Studies in the infra-red region of the spectrum. Part I.—Description of prism spectrometer and apparatus

1928 ◽  
Vol 120 (784) ◽  
pp. 128-148 ◽  
Keyword(s):  
Molecular Structure ◽  
Absorption Spectrum ◽  
Absorption Bands ◽  
Infra Red

For a projected investigation on the rate of decomposition of an explosive gas, arsenic hydride, it became necessary to know its absorption in the region of the infra-red. From preliminary trials with a small infra-red spectrometer, a series of absorption bands possessing certain regularities was observed in this region, whereupon a larger prism instrument was obtained capable of giving values up to 17 μ. Interest in the absorption spectrum of arsenic hydride led to the exploration of the same region for phosphine and for ammonia. In the following papers will be described the apparatus and methods adopted and the results found for these three gases, together with a comparison of inter-relationships and their bearing on molecular structure.

scholarly journals Investigations in the infra-red region of the spectrum. Part III.—The absorption spectrum of carbon disulphide

1931 ◽  
Vol 132 (819) ◽  
pp. 236-251 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Carbon Disulphide ◽  
Present Series ◽  
Liquid Carbon ◽  
Vapour State ◽  
Infra Red

The absorption spectrum of liquid carbon disulphide has been previously determined by Coblentz. The apparatus described in Part I of the present series offers a higher degree of resolution and a greater range of the spectrum than were available to the former worker. It was accordingly decided to examine this substance in the vapour state, and this paper gives an account of the absorption spectrum between 1 and 22 μ .

Vibration-rotation bands of methane

1952 ◽  
Vol 213 (1112) ◽  
pp. 42-54 ◽  
Keyword(s):  
Complex System ◽  
Absorption Spectrum ◽  
Fine Structure ◽  
Resolving Power ◽  
Absorption Bands ◽  
Infra Red ◽  
Vibration Rotation

The infra-red absorption spectrum of methane 12 CH 4 in the region of 3 μ has been re-investigated with higher resolving power than has been used previously. A very complex system of overlapping vibration bands has been revealed. The rotational fine structure of these bands has been partially analyzed, particularly having regard to the Coriolis interactions which occur in this case. The corresponding absorption bands of 13 CH 4 have also been examined.

Sign in / Sign up

Export Citation Format

Share Document