A General Method for the Localization of Electronic Transition Frequencies in Continuous Absorption Spectra

Nature ◽  
1950 ◽  
Vol 165 (4206) ◽  
pp. 931-932
Author(s):  
A. LANGSETH ◽  
SVEND BRODERSEN
Keyword(s):  
Absorption Spectra ◽  
Electronic Transition ◽  
Continuous Absorption ◽  
General Method

The absorption spectra of irradiated diamonds after heat treatment

1956 ◽  
Vol 237 (1208) ◽  
pp. 75-89 ◽  
Keyword(s):  
Absorption Spectra ◽  
Absorption Lines ◽  
Type I ◽  
Type Ii ◽  
Large Reduction ◽  
Isothermal Heating ◽  
Interstitial Carbon ◽  
Crystal Imperfections ◽  
Continuous Absorption ◽  
Kinetics Of

The absorption spectra of eight type I and three type II a diamonds irradiated with neutrons, electrons or y-rays have been recorded at 80 and 290°K after various heat treatments in the temperature range 0 to 900°C. It is found that heating in the range 350 to 450°C causes a general reduction in the irradiation-induced absorption owing to the recombination of those interstitials and vacancies which are near neighbours. Heating type II a diamonds at 600°C causes a large reduction in the irradiation-induced lines and new lines appear. These are probably due to pairs of identical defects, and the kinetics of their formation during isothermal heating at 600°C are presented. At higher temperatures all absorption lines in type II a diamonds disappear and only continuous absorption remains. This is probably due to amorphous or graphitic regions produced by agglomeration of defects. Type I diamonds show the same kind of absorption, but in addition show an increase in strength of the natural lines and also some new absorption lines which are not removed by heating at 900°C. It is suggested that these additional processes are due to the anchoring of vacant atomic sites and interstitial carbon atoms at crystal imperfections present only in type I diamonds.

Polarisationsgradspektren mehrkerniger Aromaten: Tetracen, 3.4-Benztetraphen, 1.2, 3.4-Dibenzanthracen, 1.2, 5.6-Dibenzanthracen, Picen, Pentaphen

1967 ◽  
Vol 22 (7) ◽  
pp. 1097-1108
Author(s):  
Reiner Kiessling ◽  
Georg Hohlneicher ◽  
Friedrich Dörr
Keyword(s):  
Absorption Spectra ◽  
Electronic Transition ◽  
Relative Polarization ◽  
Vibronic Transitions ◽  
Polarization Spectra ◽  
Α Band

Absorption, luminescence and polarization spectra of tetracene and five five-ringed catacondensed aromatics have been analysed. The relative polarization of vibronic transitions is given for molecules of symmetric D2h and C2v. A new electronic transition, not detectable in the absorption spectra, has been found in all five-membered compounds, lying between 30 000 and 42 000 cm-1. The vibrational pattern of the α-band is determined by at least two series of vibrations.

scholarly journals Transient absorption and laser gain in e-beam-excited Ar/Kr/NF3(F2 + N2) gas mixtures

2011 ◽  
Vol 29 (1) ◽  
pp. 141-152
Author(s):  
N.N. Ustinovskii ◽  
A.O. Levchenko ◽  
V.D. Zvorykin
Keyword(s):  
Absorption Spectrum ◽  
Absorption Spectra ◽  
Transient Absorption ◽  
Optical Gain ◽  
Plasma Source ◽  
Single Shot ◽  
Optical Amplification ◽  
Excitation Rate ◽  
Broadband Absorber ◽  
Continuous Absorption

AbstractNewly developed erosion-plasma-source probe technique has been applied for virtually single shot recording of absorption/fluorescence spectra in the 190–510 nm spectral range of e-beam-excited Ar/Kr/NF3(F2 + N2) mixtures. The e-beam excitation rate of about 1 MW/cm3 is typical of large-volume rare-gas halide lasers. It is experimentally observed that, in Kr/F2 and Ar/F2 mixtures, fluorescence and absorption spectra of Rg2F species are shifted with respect to each other in the opposite direction. Continuous absorption spectrum of Ar2F excimer is reported, as far as we know, for the first time in the refereed literature. Strong overlapping between the fluorescence and absorption spectra of Ar2F is responsible for absence of lasing on Ar2F molecule. Absorption spectrum of Kr2F excimer is recorded in pure form using the mixture (Ne/Kr/F2) with no alternative broadband absorber. Minor additive of nitrogen to Ar/Kr/F2 mixture or use of NF3 instead of F2 has been found to result in broadband optical amplification centered at λ ~ 460 nm. The maximum optical gain is estimated as about 0.1 ± 0.05 m−1.

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 ).

TRYPTAMINES, CARBOLINES, AND RELATED COMPOUNDS: PART IX. THE CYCLIZATION OF SOME NITRO- AND AZIDO-PHENYLPYRIDINES. PYRIDO[1,2-b]INDAZOLE

1961 ◽  
Vol 39 (12) ◽  
pp. 2516-2528 ◽  
Author(s):  
R. A. Abramovitch ◽  
K. A. H. Adams
Keyword(s):  
Absorption Spectra ◽  
Catalytic Reduction ◽  
Nitro Compounds ◽  
Ultraviolet Absorption ◽  
The Other ◽  
Azo Compounds ◽  
Minute Amount ◽  
Ferrous Oxalate ◽  
Related Compounds ◽  
General Method

Heating 2-o-nitrophenylpyridine with ferrous oxalate gives rise to pyrido[1,2-b]indazole (III). The evidence for the structure of this compound is discussed. Similarly, heating 2-o-nitrophenylpyridine methiodide and N-oxide with ferrous oxalate gives (III), in each case, demethylation and deoxygenation preceding the cyclization. In the latter case a minute amount of δ-carboline is also formed. Heating pyridine-N-oxides with ferrous oxalate is a potentially general method of effecting deoxygenations of these compounds. Contrary to the results of Smith and Boyer (11), it is found that heating 2-o-azidophenylpyridine also gives rise to (III). On the other hand, the action of heat on 2-o-azidophenyIpyridine-N-oxide gives a mixture of δ-carboline and δ-carboline-py-N-oxide in low yield. The mechanism of the cyclization of the azides and of the reaction taking place on heating nitro-compounds with ferrous oxalate is discussed briefly; the formation of a nitrene intermediate is favored.The catalytic reduction of 2-o-nitrophenylpyridine-N-oxide giving rise to the azoxy-, azo-, and hydrazo-derivatives is described and the ultraviolet absorption spectra of these compounds are discussed. It is concluded the steric inhibition of coplanarity exists in the azoxy- and azo-compounds leading to the lack of effective conjugation across the N=N bond.

Potential barrier effects beyond the 4f photoionization thresholds in Pb I

1976 ◽  
Vol 348 (1653) ◽  
pp. 235-238 ◽  
Keyword(s):  
Absorption Spectra ◽  
Potential Barrier ◽  
Central Field ◽  
Discrete Structure ◽  
Barrier Effects ◽  
Independent Particle ◽  
Continuous Absorption

New Pb I absorption spectra show discrete structure due to excitation of the 4f subshell and continuous absorption beyond the 4f thresholds. The results are compared with those previously obtained in Tl I and Hg I, and the presence of additional maxima in the Pb I spectrum is accounted for by comparison with recent independent-particle non-relativistic central field calculations.

The Electronic Absorption Spectra of Some N-Substituted Pyrroles—Molecular Orbital Calculations

1982 ◽  
Vol 36 (3) ◽  
pp. 297-301 ◽  
Author(s):  
R. Abu-Eittah ◽  
R. Hilal ◽  
M. S. El-Shall
Keyword(s):  
Absorption Spectra ◽  
Molecular Orbital ◽  
Electronic Absorption ◽  
Electronic Transition ◽  
Electronic Absorption Spectra ◽  
Experimental Results ◽  
Electronic Transitions ◽  
Molecular Orbital Calculations ◽  
Nonpolar Solvents ◽  
State Functions

The electronic absorption spectra of N-phenylpyrrole and some of its parasubstituted derivatives have been investigated in polar and nonpolar solvents. Such an investigation could predict the extent of resonance interaction between the pyrryl and phenyl moieties of the composite molecule. The direction and polarization of the electronic transitions were predicted. Molecular orbital calculations using the SCF-CI procedures were performed on N-phenylpyrrole and some of its p-substituted derivatives. The state functions and energies were computed. The weight of each configuration was evidence for the direction of the electronic transition. The correspondence between the theoretical and experimental results is satisfactory.

Studies of the explosive combustion of hydrocarbons by kinetic spectroscopy - II. Comparative investigations of hydrocarbons and a study of the continuous absorption spectra

1955 ◽  
Vol 227 (1171) ◽  
pp. 423-433 ◽  
Keyword(s):  
Absorption Spectra ◽  
Thermal Equilibrium ◽  
Flash Photolysis ◽  
Total Carbon ◽  
Carbon Particles ◽  
Continuous Absorption ◽  
Flash Spectroscopy ◽  
Characteristic Maximum ◽  
The Continuum ◽  
Carbon Molecule

The absorption spectra of explosions of ethylene, ethane and methane with oxygen, initiated by the flash photolysis of nitrogen dioxide, have been studied kinetically by flash spectroscopy and the results are compared with those already given for acetylene. The occurrence of the diatomic radical spectra is qualitatively similar in the four hydrocarbons, but there are important quantitative differences in the stoicheiometry of the mixtures which give equivalent spectroscopic results. The continuous spectra and the spectrum of C 3 have been studied in more detail. The continuum which is present after the explosion is shown to be due to absorption by carbon particles. A second intense continuous spectrum, which has a characteristic maximum at 3900 Å and whose occurrence follows closely that of the radicals C 2 and C 3 , is attributed to a carbon molecule which is in approximate thermal equilibrium and whose concentration must form a considerable fraction of the total carbon present in the vapour during the explosion.

Correlation of absorption spectra and structure of some Co(II)– and Ni(II)–2,2′-biquinoline complexes

1967 ◽  
Vol 45 (20) ◽  
pp. 2335-2345 ◽  
Author(s):  
G. H. Faye ◽  
J. L. Horwood
Keyword(s):  
Field Theory ◽  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Transition ◽  
Near Infrared ◽  
Magnetic Measurements ◽  
Electronic Absorption Spectra ◽  
General Interest ◽  
Ligand Field ◽  
Ligand Field Theory

Co(II)– and Ni(II)–2,2′-biquinoline (Biq) complexes of the type MBiqCl2 and MBiq(NO3)2 have been isolated. Electronic absorption spectra in the visible and near infrared, as well as magnetic measurements, show that CoBiqCl2 is essentially tetrahedral, whereas NiBiqCl2 and the MBiq(NO3)2 complexes are pseudo-octahedral. In acetone solution Co(II) forms a bis-Biq complex that is probably five coordinate, whereas the Ni(II) analogue is probably an octahedral species with a cis configuration. Elementary ligand field theory has been used to interpret the absorption spectra, and certain electronic transition assignments have been made that may be of general interest.

THE ABSORPTION SPECTRUM OF NO2 IN THE 3 700–4 600 Å REGION

1965 ◽  
Vol 43 (1) ◽  
pp. 74-81 ◽  
Author(s):  
A. E. Douglas ◽  
K. P. Huber
Keyword(s):  
Absorption Spectrum ◽  
Absorption Spectra ◽  
Electronic Transition ◽  
Rotational Analysis

An investigation of the absorption spectra of both 14NO2 and 15NO2 has revealed a long progression of red-degraded bands in the region 3 700–4 600 Å. The rotational analysis shows that these bands are the Ka = 0 ← 1 subbands of the electronic transition 2B1 ← 2A1. The interpretation of the bands is discussed, and a few remarks concerning the onset of predissociation at 3 979 Å are added.

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