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.

ABSORPTION SPECTRA OF C3 AND C3H2 FROM THE FLASH PHOTOLYSIS OF DIAZOPROPYNE

1967 ◽  
Vol 45 (12) ◽  
pp. 4103-4111 ◽  
Author(s):  
A. J. Merer
Keyword(s):  
Absorption Spectrum ◽  
Free Radical ◽  
Ground State ◽  
Time Delays ◽  
Flash Photolysis ◽  
State Level ◽  
Vibrational Structure ◽  
Absorption Bands ◽  
Text Component ◽  
Ground State Level

The flash photolysis of diazopropyne (HC2∙CHN2) provides a particularly strong absorption spectrum of the free C3 radical. About 40 μs after the photolysis flash, the appearance of the [Formula: see text] (4 050 Å) system of C3 is similar to that obtained in the flash photolysis of diazomethane by Gausset, Herzberg, Lagerqvist, and Rosen, though much more intense. The intensity of the spectrum has permitted a study of the l-type doubling effect in the ground-state level 6ν2, of which the [Formula: see text] component has been found to lie at 458.2 cm−1. At shorter time delays [Formula: see text] the spectrum is complicated by bands arising from the levels ν1″ (1 224.5 cm−1) and 2ν1″ (2 436.0 cm−1).Below 3 700 Å the C3 spectrum is overlapped by absorption bands belonging to a new free radical, which has been identified from the intensity alternation in the rotational structure as the HCCCH radical. The vibrational structure of this system is exceptionally complex, and analysis has not been possible. The bands extend to about 3 100 Å, but are predissociated below 3 450 Å.

The ultraviolet absorption spectrum of the F 2 CN radical

1967 ◽  
Vol 300 (1462) ◽  
pp. 405-414 ◽  
Keyword(s):  
Molecular Structure ◽  
Absorption Spectrum ◽  
Ground State ◽  
Flash Photolysis ◽  
Ultraviolet Absorption ◽  
Ultraviolet Absorption Spectrum ◽  
Rotational Analysis ◽  
Absorption Bands ◽  
New System

A new system of absorption bands near 3600 Å has been observed during the flash photolysis of CF 3 NCF 2 and is ascribed to the free F 2 CN radical. The rotational analysis of the 0–0 band leads to the ground state molecular structure r CF = 1.310 Å (assumed), r CN = 1.265 ± 0.02 Å, FCF angle = 113.5 + 1°. The bands are shown to be type A bands arising from the transition 2 A 1 ← 2 B 2 , and the spectrum is compared with those of the iso-electronic molecules NO 3 and F 2 BO.

The absorption spectrum of KBr:Sn2+

1982 ◽  
Vol 60 (5) ◽  
pp. 619-627 ◽  
Author(s):  
A. Scacco ◽  
P. W. M. Jacobs
Keyword(s):  
Absorption Spectrum ◽  
Theoretical Model ◽  
Absorption Spectra ◽  
Cation Vacancy ◽  
Relative Concentration ◽  
Hamiltonian Matrix ◽  
Absorption Bands ◽  
Different Types ◽  
Experimental Absorption ◽  
Good Agreement

Thorough annealing on crystals of KBr.Sn2+ results in significant changes in their absorption spectra. These changes have been interpreted as the effect of the annealing on the relative concentration of different types of Sn2+ centres: isolated Sn2+ substitutional ions ("cubic" centres) and Sn2+–cation vacancy complexes ("tetragonal" and "rhombic" centres). The line shape of the optical absorption has been calculated theoretically, by diagonalizing the complete 12 × 12 Hamiltonian matrix, for cubic centres only, for tetragonal centres only, and for different relative concentrations of cubic and tetragonal centres. The experimental absorption spectra of KBr:Sn2+ crystals that have undergone various annealing treatments are in good agreement with theoretical spectra calculated for appropriate mixtures of the above centres. These results confirm that thorough annealing increases the fraction of isolated Sn2+ substitutional ions at the expense of the Sn2+–cation vacancy complexes. The consistency of the theoretical model is demonstrated by the agreement of the calculated moments of the absorption bands of KBr:Sn2+ with the experimentally derived values.

The electronic spectra of phenyl radicals

1965 ◽  
Vol 287 (1411) ◽  
pp. 457-470 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Electronic Absorption Spectrum ◽  
Electronic Absorption ◽  
Ground State ◽  
Electronic Spectra ◽  
Flash Photolysis ◽  
Visible Region ◽  
Electronic Configuration ◽  
Vibrational Structure ◽  
Fundamental Frequencies

An electronic absorption spectrum, attributed to phenyl, has been observed in the visible region with origin at 18 908 cm -1 after flash photolysis of benzene and halogenobenzenes. Similar spectra of fluoro, chloro and bromo phenyl are observed after flash photolysis of disubstituted benzenes. The vibrational structure of the phenyl spectrum has been analysed in terms of two fundamental frequencies at 571 and 896 cm -1 which correspond to the e 2 g and a 1 g frequencies of the B 2 u state of benzene. The ground state of phenyl has a π 6 n electronic configuration and the observed transition is interpreted as 2 A 1 → 2 B 1 resulting from a π → n excitation.

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.

Synthesis and Characterization of Novel Platinum Acetylide Oligomers

2003 ◽  
Vol 771 ◽  
Author(s):  
Thomas M. Cooper ◽  
Benjamin C. Hall ◽  
Daniel G. McLean ◽  
Joy E. Rogers ◽  
Aaron R. Burke ◽  
...  
Keyword(s):  
Absorption Spectra ◽  
Ground State ◽  
Near Infrared ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Structure Property ◽  
Ground State Absorption ◽  
Excitation Spectra ◽  
C Nmr

AbstractAs part of an effort to develop a spectroscopic structure-property relationship in platinum acetylide oligomers, we have prepared a series of bidentate Pt(PBu3)2L2 compounds. The ligand was the series o-syd-C6H4-CΞC-(C6H4-CΞC)n-H, n = 0,1,2. The terminal oligomer unit consisted of a sydnone group ortho to the acetylene carbon. The compounds were characterized by various methods, including 13C-NMR, ground state absorption, fluorescence, phosphorescence and laser flash photolysis. The acetylenic 13C-NMR resonances showed sydnone influences that decreased with increasing number of monomer units. The ground state absorption spectra were slightly red shifted from those of the baseline oligomers not having a sydnone group. The low temperature emission and excitation spectra showed complex dependence on excitation and emission wavelengths, suggesting the chromphores resided in a distribution of solvent environments and conformations. Finally, broad triplet state absorption spectra were observed, with absorption throughout the visible and near infrared regions.

Thiophosgene monomer–dimer equilibria in perfluoroalkane solutions: spectroscopic and photophysical implications of self-association in the ground state

1993 ◽  
Vol 71 (10) ◽  
pp. 1548-1555 ◽  
Author(s):  
Andrzej Maciejewski ◽  
Marian Szymanski ◽  
Ronald P. Steer
Keyword(s):  
Absorption Spectrum ◽  
Oscillator Strength ◽  
Absorption Spectra ◽  
Strong Evidence ◽  
Ground State ◽  
Excitation Spectra ◽  
Direct Excitation ◽  
Self Association ◽  
Single Formula ◽  
Self Aggregation

The S2–S0 absorption, emission, and emission excitation spectra of thiophosgene in a perfluoroalkane solvent have been measured as a function of the analytical concentration, C, of the solute. Strong evidence of the formation of van der Waals dimers at 10−4 M < C < 10−1 M and of higher oligomers at C > 10−1 M has been found. Variations in the absorption spectra at C < 10−1 M have been analyzed successfully in terms of a single [Formula: see text] equilibrium, for which the value of K is (5.0 ± 0.4) × 102 M−1 at 295 K. The mole fractions of monomer and dimer have been calculated at each C, and have been used to construct the absorption spectrum of the dimer. Both the monomer and dimer have similar S0 → S1, and S0 → S2 absorption spectra, but the dimer has an oscillator strength that is about twice that of the monomer. The effects of self-aggregation on the S2–S0 emission and excitation spectra have been analyzed. Absorption by the dimer in the ultraviolet also leads to emission, but with a different quantum efficency compared with direct excitation of the monomer. The implications of these observations on the interpretation of the spectroscopy, photophysics, and photochemistry of thiophosgene in solution are assessed.

Photochemical Electron Transfer in the System Polypyrrole-Methylene Blue

1994 ◽  
Vol 47 (6) ◽  
pp. 1163 ◽  
Author(s):  
D Matthews ◽  
A Altus ◽  
A Hope
Keyword(s):  
Methylene Blue ◽  
Electron Transfer ◽  
Absorption Spectrum ◽  
Absorption Spectra ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Vitamin K1 ◽  
Photochemical Reduction ◽  
Long Chain

Methylene Blue incorporated into colloidal oxidized polypyrrole was investigated by absorption spectroscopy and laser flash photolysis. The absorption spectra of Methylene Blue and polypyrrole were unaffected by incorporation. Flash photolysis transients of Methylene Blue and triplet Methylene Blue in ethanol were affected by 1,4-benzoquinone and 1,4-benzoquinol but not by the long-chain naphthoquinone Vitamin K1. Incorporation of Methylene Blue in polypyrrole produced distinct changes in the flash photolysis transients of Methylene Blue and triplet Methylene Blue. Very long-lived transients, with lifetimes of the order of 10 ms, were observed. These effects were accompanied by long-lived changes in the absorption spectrum of Methylene Blue. The transients were modified by the addition of 1,4-benzoquinone but not 1,4-benzoquinol. The results indicate photochemical reduction of oxidized polypyrrole by triplet Methylene Blue with the production of stable long-lived species capable of reducing 1,4-benzoquinone.

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 ).

THE ABSORPTION SPECTRUM OF BO2

1961 ◽  
Vol 39 (12) ◽  
pp. 1738-1768 ◽  
Author(s):  
J. W. C. Johns
Keyword(s):  
Absorption Spectrum ◽  
Excited State ◽  
Detailed Analysis ◽  
Ground State ◽  
Flash Photolysis ◽  
Electronic Transitions ◽  
Molecular Constants ◽  
Boron Trichloride ◽  
Symmetric Molecule ◽  
First Excited State

The boron flame bands have been observed in absorption during the flash photolysis of mixtures of boron trichloride and oxygen. Detailed analysis of the spectrum has shown that the bands arise from two electronic transitions in the linear symmetric molecule BO2, [Formula: see text] and A2Πu−X2Πg. The main molecular constants, in cm−1 except for r0, are summarized below:[Formula: see text]Both 2Π states show the Renner effect. In the ground state the Renner parameter, εω2, was found to be −92.2, whereas in the first excited state it is much smaller, −13.1 cm−1.

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