scholarly journals On the fluorescence and channelled absorption spectra of cæsium and other alkali elements

1923 ◽  
Vol 103 (721) ◽  
pp. 304-314 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Fluorescence Spectrum ◽  
Absorption Spectra ◽  
Wave Length ◽  
Monochromatic Light ◽  
Exciting Light ◽  
Absorption Bands ◽  
The Mean ◽  
Alkali Elements ◽  
Different Sources

In 1874 it was shown by Roscoe and Schuster that channelled absorption spectra can be obtained with the vapours of the alkali elements sodium and potassium, and later on these spectra were investigated in some detail by Liveing and Dewar. It was also shown in 1896 by Weidemann and Schmidt that the vapours of these same metals emitted a radiation possessing characteristics of a fluorescence spectrum when they were traversed by white light. Since 1903 exhaustive studies have been made of both the fluorescence and the channelled absorption spectrum of sodium by R. W. Wood, together with a number of collaborators, Including J. H. Moore and F. E. Hackett. In these investigation it was shown that the channelled absorption spectrum of sodium was made up of a number of series of absorption bands, one set of series being on the red wave-length side of the D lines, and another lying in the visible blue-green region. In addition, series of absorption bands were found by them with approximately regular spacing in the neighbourhood of λ = 3303 A, the second member of the doublet series of this element. As regards the fluorescence spectrum of sodium, they found that, by stimulation of the vapour with approximately monochromatic light, there resulted an emission of light, the spectrum of which consisted of a number of bright but narrow bands of varying intensity, more or less regularly spaced both above and below the mean wave-length of the exciting light. They observed, too, that the slightest change in the wave-length of the exciting light resulted in the disappearance of one set of lines and in the appearance of another of different wave-lengths. In the various florescence spectra obtained by R. W. Wood when stimulating sodium vapour by monochromatic light from different sources, it was noted that there was a remarkable recurrence of the interval, ∆ λ = 52·3 A. in the spacing of the fluorescence bands.

scholarly journals The absorption spectra of halogens and inter-halogen compounds in solution in carbon tetrachloride

1929 ◽  
Vol 124 (795) ◽  
pp. 604-616 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Carbon Tetrachloride ◽  
Absorption Spectra ◽  
Spectroscopic Data ◽  
Chemical Interaction ◽  
Chemical Compounds ◽  
Absorption Bands ◽  
Halogen Compounds ◽  
Inert Solvent ◽  
The Mean

When two solutions are mixed the absorption spectrum of the new solution will be the mean of those of the separate solutions provided that no chemical interaction occures. The mere fact of a departure from additivity does not, however, necessarily denote the formation of true chemical compounds. The solute or solutes may undergo solvation, loosely bound aggregates may occur, and even when marked deviations from the simple law of mixtures are observed it is rarely possible to prove the quantitative formation of a given chemical compound from spectroscopic data alone. The above considerations apply with some force to the problem of the absorption spectra of halogens and inter-halogen compounds in an inert solvent. The three elements show perfectly characteristic absorption bands, they are known to interact with the formation of some quite stable compounds, some relatively stable compounds, and some apparently very unstable compounds.

scholarly journals IV. On the absorption-spectra of bromine and iodine monochloride

1877 ◽  
Vol 25 (171-178) ◽  
pp. 4-4
Keyword(s):  
Absorption Spectrum ◽  
Absorption Spectra ◽  
Graphical Method ◽  
Wave Length ◽  
Iodine Monochloride ◽  
Absorption Bands ◽  
General Applicability ◽  
Molecular Weights

The paper contains the results of an exact series of measurements of the absorption-spectra of the vapours of the element bromine and of the compound iodine monochloride, made with the object of ascertaining whether the molecules of these two gases vibrate identically or similarly, their molecular weights and colour of the vapours being almost identical. The two spectra, which are both channelled, were compared simultaneously by means of one of Kirchhoff’s 4-prism spectroscopes, the position of the lines being read off by reflection on an arbitrary scale. In order to determine the wave-lengths of these bands, the wave-length of each of 27 air-lines lying between the extremes of the absorption-spectra was ascertained by reference to Thalén’s numbers; whilst for the purpose of reducing the readings of the absorption-bands to wave-lengths a graphical method was employed, the details of which are given in the paper. This method appears to be one of general applicability for the plotting of spectra. Tables then follow giving the wave-lengths of 66 bands of each absorption-spectrum; and a map accompanies the text in which the bands are drawn to a scale one half that of Ångström’s “Spectre Normal.”

Electronic Spectroscopy of Mixed Cyclophanes: [2.2](9,10)Anthraceno(1,4)naphthalenophane

1989 ◽  
Vol 42 (12) ◽  
pp. 2201 ◽  
Author(s):  
J Ferguson ◽  
RJ Robbins ◽  
GJ Wilson
Keyword(s):  
Absorption Spectrum ◽  
Single Crystal ◽  
Fluorescence Spectrum ◽  
Absorption Spectra ◽  
Fluorescence Polarization ◽  
Fluorescence Spectra ◽  
Electronic Spectroscopy ◽  
Absorption And Fluorescence Spectra ◽  
Absorption Bands ◽  
Absorption Intensity

The absorption and fluorescence spectra of [2.21(9,10) anthraceno (1,4) naphthalenophane are reported. The anisotropy of the absorption bands was measured by two methods, ( i ) from fluorescence polarization ratios in a rigid glass and (ii) from single crystal absorption spectra at 23 K. The two states arising from the 1La states of the two chromophores were identified together with two states arising from other chromophore 1B2u states. Two states arising from the 1La states of the two chromophores were also identified. Whereas a coupled chromophore model accounts reasonably well for the latter two states, the energies and intensities of the bands arising from 1La chromophore states cannot be reconciled with this approach. Long axis polarized absorption intensity lying under the 1La, bands appears to be vibronically induced and not due to the 1Lb states. The absorption spectrum, fluorescence spectrum and fluorescence polarization ratios of a stable dimer were also observed. Its structure is similar to that of the stable dimer of anthracene in which the molecular long axes are parallel but the short axes make an angle of about 70� with each other.

scholarly journals The infra-red absorption spectra of quartz and fused Silica from 1 to 7·5 μ II-Experimental results

1936 ◽  
Vol 153 (879) ◽  
pp. 328-339 ◽  
Keyword(s):  
Water Vapour ◽  
Absorption Spectra ◽  
Wave Length ◽  
Fused Silica ◽  
Experimental Results ◽  
Wave Number ◽  
Infra Red ◽  
The Mean ◽  
Point To Point ◽  
Maximum Discrepancy

The accuracy of calibration, as already mentioned, was checked against CO 2 and water vapour bands. With the quartz prism the instrument could be set to show the 2·7 μ CO 2 bands resolved and within about 0·003μ of their known wave-lengths*; i. e., within 4 cm -1 . With the fluorite prism, resolution at 2·7 μ was inferior, but the structure of the water vapour band centred at 6·3 μ provided about 20 points for the checking of wave-lengths. Here the maximum discrepancy was 5 cm -1 and the mean discrepancy about 1·5 cm -1 , The wave-number error, therefore, is not libels to exceed 5 cm -1 in any part of the range investigated. The fraction of radiation transmitted by a specimen was measured to three figures and a mean of two or three observations at least taken for each wave-length setting. The accuracy varies from specimen to specimen and from point to point throughout the spectrum, depending on the magnitude of the galvanometer deflexions obtainable. The error is, however, nowhere likely to be greater than 0·01 and for much of the work is of the order of 0·002.

Thickness-Dependent Optical Effects in Infrared Reflection-Absorption Spectra of a Fairly Thick Polymer Layer

2002 ◽  
Vol 56 (1) ◽  
pp. 24-30 ◽  
Author(s):  
Marta KlanjšEk Gunde ◽  
Zorica Crnjak Orel
Keyword(s):  
Absorption Spectra ◽  
Normal Incidence ◽  
Peak Position ◽  
Mean Value ◽  
Absorption Bands ◽  
Medium Thickness ◽  
Peak Intensity ◽  
Infrared Reflection ◽  
Optical Effects ◽  
The Mean

Thickness-dependent intensities and positions of absorption lines in infrared reflection-absorption spectra of thin films on reflective substrates at near-normal incidence are investigated. Two types of absorption bands in a polymer, the weak and the strong, were examined. Their optical properties were determined by the dielectric response function. The optical path of the beam was described by the coherent sum of all successively reflected beams. The thickness-dependent properties of absorption bands were examined in three typical thickness regions. At small thickness, the peak intensity oscillates around the mean value defined by the simple internal absorptance of the beam crossing the double layer. For medium thickness, the peak position swings around the original frequency and its intensity oscillations move above the simple internal absorptance. In layers within the high-thickness region, optical distortions cause large changes in line shape due to approaching the bulk reflectance. A simple analytical interpretation is possible only within the low-thickness region. The width of these thickness regions depends on the absorptivity of the considered band; for strong bands they are considerably narrower than for weak bands. The theoretically predicted effects compare well with those measured in RAS spectra of variously thick silicon resin layers on aluminium substrates.

The A2Πi–X2Πi absorption spectrum of BrO

1981 ◽  
Vol 59 (12) ◽  
pp. 1908-1916 ◽  
Author(s):  
M. Barnett ◽  
E. A. Cohen ◽  
D. A. Ramsay
Keyword(s):  
Absorption Spectrum ◽  
Absorption Spectra ◽  
Ground State ◽  
Flash Photolysis ◽  
Absorption Bands ◽  
Long Wavelength ◽  
Numbering Scheme ◽  
Ozonized Oxygen ◽  
Good Agreement

Absorption spectra of isotopically enriched 81Br16O and of normal BrO have been obtained by the flash photolysis of mixtures of bromine and ozonized oxygen. Rotational analyses are given for the 7–0, 12–0, 18–0, 19–0, 20–0, 21–0, 7–1, and 20–1 A2Π3/2–X2Π3/2 sub-bands of 81Br16O. The value for [Formula: see text] is found to be 722.1 ± 1.1 cm−1 in good agreement with the value calculated from microwave constants. Several additional bands have been found at the long wavelength end of the spectrum, necessitating a revision of the vibrational numbering scheme for both the emission and absorption bands. "Hot" bands up to ν″ = 6 have been observed in the absorption spectrum for the 2Π3/2 component of the ground state but no bands have yet been identified from the 2Π1/2 component.

The absorption spectrum of liquid bromine

1937 ◽  
Vol 162 (910) ◽  
pp. 414-419 ◽  
Author(s):  
D. Porret ◽  
Frederick George Donnan
Keyword(s):  
Absorption Spectrum ◽  
Absorption Spectra ◽  
Ground State ◽  
Wave Length ◽  
Electronic States ◽  
Excited Electronic States ◽  
Long Wave ◽  
Liquid Bromine ◽  
Continuous Absorption ◽  
The Continuum

The continuous absorption spectra of gaseous bromine (Peskow 1917; Ribaud 1919; Gray and Style 1929; Acton, Aikin and Bayliss 1936) and of dissolved bromine (Bovis 1929; Gillam and Morton 1929) have been studied many times. They present a wide continuum (from about 30, 000 to 17, 000 cm. -1 .) with a maximum at 24, 000 cm. -1 . For the gas the continuum is preceded by two band systems on the long wave-length side. These systems converge at 19, 585 and 15, 896 cm. -1 . respectively. Acton, Aikin and Bayliss (1936) have shown that the continuum is not simple, and Mulliken (1936) and Darbyshire (1937) have pointed out that there are three overlapping continua corresponding to transitions from the ground state to three different excited electronic states. There are 3 II 0 + ← 1 Σ g , 3 II 1 ← 1 Σ g and 1 II ← 1 Σ g . The absorption spectrum of liquid bromine has been studied by Bovis (1929) form 18, 525 to 31, 750c cm. -1 . and by Camichel (1893) for two frequencies only (16, 978 and 18, 691 cm. -1 ).

scholarly journals The absorption spectra of conjugated dienes in the vacuum ultra-violet (1)

1940 ◽  
Vol 174 (957) ◽  
pp. 220-234 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Absorption Spectra ◽  
Electronic Structures ◽  
Spectroscopic Data ◽  
Ultra Violet ◽  
Conjugated Dienes ◽  
Strong Absorption ◽  
Absorption Bands ◽  
Lennard Jones ◽  
Vacuum Ultra Violet

Butadiene is important as the simplest example of resonance between two conjugated double bonds. The comparison of its ultra-violet absorption spectrum with that of ethylene might be expected to give some indication of the way the π electrons of the molecule are affected by the resonance. The electronic structures of a number of molecules for which resonance is important have been worked out theoretically by Hückel (1935), Lennard- Jones (1937), Sklar (1937) and Mulliken (1939 a and b ). The purpose of the present work is to obtain spectroscopic data with which the theoretical expectations can be compared. As most of the strong absorption bands of these molecules occur at wave-lengths less than 2000 A, the investigation falls naturally into the region of vacuum spectroscopy.

Spectroelectrochemical Study of some μ3-Oxo-μ-acetato Trinuclear Rhodium(III) and Iridium(III) Complexes

1995 ◽  
Vol 50 (4) ◽  
pp. 551-557 ◽  
Author(s):  
Kenta Takahashi ◽  
Keisuke Umakoshi ◽  
Akihiro Kikuchi ◽  
Yoichi Sasaki ◽  
Masato Tominaga ◽  
...  
Keyword(s):  
Absorption Spectrum ◽  
Electronic Absorption Spectrum ◽  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Visible Region ◽  
Absorption Bands ◽  
Visible Absorption ◽  
The One ◽  
Species Being

New trinuclear rhodium(III) complexes, [Rh3(μ3-O)(μ-CH3COO)6(L)3]+ (L = imidazole (Him), 1-methylimidazole (Meim), and 4-methylpyridine (Mepy)) have been prepared. The Him, Meim, and Mepy complexes show reversible one-electron oxidation waves at E1/2 = +1.12, +1.12, and +1.28 V vs Ag/AgCl, respectively, in acetonitrile. Electronic absorption spectra of the one electron oxidized species of these complexes and [Rh3(μ3-O)(μ-CH3COO)6(py)3]+ (py = pyridine) (E1/2 = +1.32 V ) were obtained by spectroelectrochemical techniques. While the Rh3(III,III,III) states show no strong visible absorption, the Rh3(III,III,IV ) species give a band at ca. 700 nm (ε = 3390-5540 mol dm-3 cm-1). [Ir3(μ3-O)(μ-CH3COO)6(py)3]+ with no strong absorption in the visible region, shows two reversible one-electron oxidation waves at +0.68 and +1.86 V in acetonitrile. The electronic absorption spectrum of the one-electron oxidized species (Ir3(III,III,IV )) also shows some absorption bands (688 nm (ε, 5119), 1093 (2325) and 1400 (ca. 1800)). It is suggested that the oxidation removes an electron from the fully occupied anti-bonding orbital based on metal-dπ-μ3-O-pπ interactions, the absorption bands of the (III,III,IV ) species being assigned to transitions to the anti-bonding orbital.

Interpretation of the optical absorption spectrum of Ni-substituted lizardites

Clay Minerals ◽  
1984 ◽  
Vol 19 (1) ◽  
pp. 107-111 ◽  
Author(s):  
A. Julg ◽  
O. Julg
Keyword(s):  
Absorption Spectrum ◽  
Optical Absorption ◽  
Crystal Field ◽  
Optical Absorption Spectrum ◽  
Octahedral Site ◽  
Tetrahedral Site ◽  
Absorption Bands ◽  
The Mean

The spectrum of Ni-substituted lizardite, (Mg,Ni)3Si2O5(OH)4, has been discussed by many authors, who have successively given contradictory interpretations concerning the symmetry of the Ni-sites. Lakshman & Reddy (1973) affirmed that in garnierites Ni is in a tetrahedral site. Faye (1974) rejected this conclusion and showed that Ni2+ occupies an octahedral site. However, the Ni … O distance of 2·01 Å which he deduced from the intensity of the crystal field is unacceptable. Recently, using a completely different approach to the interpretation of the spectrum, Cervelle & Maquet (1982) claimed that Ni2+ occupies a six-coordinated site of C3v symmetry, and concluded that the mean Ni … O distance is 2·06 Å.The aim of this note is to show that it is possible to interpret the spectrum of Ni-lizardite as arising from a predominantly octahedral field with a weak C2v component which provokes a small increase in width of the absorption bands.

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