scholarly journals Photodissociation dynamics in the first absorption band of pyrrole. I. Molecular Hamiltonian and the Herzberg-Teller absorption spectrum for the A21(πσ*)←X̃1 A1(ππ) transition

2018 ◽  
Vol 148 (10) ◽  
pp. 104103 ◽  
Author(s):  
David Picconi ◽  
Sergy Yu. Grebenshchikov
Keyword(s):  
Absorption Spectrum ◽  
Absorption Band ◽  
Molecular Hamiltonian

scholarly journals Absorption and Emission Spectra for C60 Anions

1994 ◽  
Vol 14 (1-3) ◽  
pp. 155-160 ◽  
Author(s):  
Tatsuhisa Kato
Keyword(s):  
Absorption Spectrum ◽  
Absorption Band ◽  
Theoretical Analysis ◽  
Room Temperature ◽  
Emission Spectra ◽  
Mirror Image ◽  
Ir Absorption ◽  
Near Ir ◽  
Laser Experiments ◽  
Ir Bands

Absorption spectra are detected for C60− and C602− produced electrolytically in solution at room temperature. Theoretical analysis of the spectrum of C60− by CNDO/S calculations gives an interpretation of the characteristic near-IR bands, the weak visible bands, and the strong bands in the UV region. The emission spectrum of C60− is a mirror image of the near-IR absorption band, and the detection of the emission reconfirms our original assignment of the absorption spectrum. The nature of the spectrum of C602− is characterized by a similar orbital picture to that of C60−. Further laser experiments of significance are proposed.

THE SIGNIFICANCE OF AN ABSORPTION BAND AT 968 CM.−1 IN THE INFRARED SPECTRUM OF METHYL ISOLINOLEATE

1949 ◽  
Vol 27b (7) ◽  
pp. 610-615 ◽  
Author(s):  
H. W. Lemon ◽  
C. K. Cross
Keyword(s):  
Fatty Acids ◽  
Absorption Spectrum ◽  
Double Bond ◽  
Absorption Band ◽  
Linseed Oil ◽  
Infrared Absorption Spectrum ◽  
Methyl Esters ◽  
Trans Configuration ◽  
Double Bonds ◽  
Identical Band

The infrared absorption spectrum of methyl isolinoleate, separated from the methyl esters of hydrogenated linseed oil fatty acids, has a well defined absorption band with maximum absorption at about 968 cm.−1 As an identical band was found in the spectra of fatty acids or esters after isomerization with selenium, it is attributed to the presence of double bonds with a trans-configuration. It was found that the same band was present in the spectra of samples taken during hydrogenation of oils, and that its intensity increased to a maximum, then decreased as hydrogenation proceeded. It is concluded that hydrogenation is accompanied by a cis-to-trans change in some of the double bonds of the fatty acids, and that methyl isolinoleate has at least one double bond with a trans-configuration.

The first absorption band for H2O: Interpretation of the absorption spectrum using time dependent pictures

1988 ◽  
Vol 89 (9) ◽  
pp. 5607-5613 ◽  
Author(s):  
Niels E. Henriksen ◽  
Jinzhong Zhang ◽  
Dan G. Imre
Keyword(s):  
Absorption Spectrum ◽  
Absorption Band ◽  
Time Dependent

Electronic absorption spectrum and π-electronic structure of cryptocyanine

1980 ◽  
Vol 45 (2) ◽  
pp. 307-320 ◽  
Author(s):  
Miloš Titz ◽  
Antonín Novák ◽  
Viktor Řehák
Keyword(s):  
Absorption Spectrum ◽  
Electronic Structure ◽  
Dipole Moment ◽  
Excited State ◽  
Absorption Band ◽  
Electronic Absorption ◽  
Quantum Chemical ◽  
Fluorescence Excitation ◽  
Real Geometry ◽  
Optimum Model

Absorption, fluorescence excitation and APF spectra of cryptocyanine have been measured. Dipole moment of the respective S1 excited state has been estimated from shifts of the marked maximum of the first absorption band in various solvents. On the basis of quantum-chemical calculations carried out by the PPP method in the approximation of quasi-real geometry we have received the optimum model of π-electronic structure of the cryptocyanine molecule and therefrom the theoretical electronic singlet spectrum inclusive character of the S0 - S1 transition.

Differences among low Ceylon zircons

1972 ◽  
Vol 38 (298) ◽  
pp. 721-724 ◽  
Author(s):  
E. R. Vance ◽  
B. W. Anderson
Keyword(s):  
Absorption Spectrum ◽  
Absorption Band ◽  
Optical Absorption ◽  
Radiation Damage ◽  
Fission Fragment ◽  
Anomalous Absorption ◽  
Optical Absorption Band

SummaryLow Ceylon zircons showing an optical absorption band at 5200 Å appear to have suffered more radiation damage than other low Ceylon zircons. Very heavy fission-fragment irradiation failed to lower the density of each of two low Ceylon zircons significantly, although the specimens were rendered completely amorphous. Further fission-fragment irradiation experiments indicated that low Ceylon zircons showing a previously reported anomalous absorption spectrum have been heated late in their geological histories.

Study of Crystal Yb3+:Ca3Y2(BO3)4

2004 ◽  
Vol 19 (4) ◽  
pp. 1203-1207 ◽  
Author(s):  
Yan Wang ◽  
Chaoyang Tu ◽  
Changcang Huang ◽  
Zhenyu You
Keyword(s):  
Absorption Spectrum ◽  
Absorption Band ◽  
Emission Spectra ◽  
Czochralski Method ◽  
X Ray Diffraction ◽  
Broad Absorption ◽  
Broad Absorption Band ◽  
Orthorhombic System ◽  
X Ray ◽  
Broad Emission

Yb3+-doped single-crystal Ca3Y2(BO3)4 with dimension φ20 × 55 mm was grown by the Czochralski method. The structure of it was determined by x-ray diffraction. It belongs to the orthorhombic system, space group Pnma, with the following parameters: a= 7.1690(4), b = 15.4758(8), c = 8.5587(6) Å, V = 949.55(10)Å3, Mr = 537.51, Z = 2, Dc = 3.8 g/cm3, (MoKa) = 0.71073 Å, F(000) = 508, μ = 6.927 mm-1, final R = 0.0670, and wR = 0.1542 for 2975 independent reflections. The structure of Yb:Ca3Y2(BO3)4 is made up of three set of M-oxygen distorted polyhedrons, and three set of BO3 planar triangles. Ca2+ and Y3+ ions occupy three M sites statistically. Yb3+ ions substitute Y3+ ions to enter these three lattices. The adsorption and emission spectra were measured. It exhibits a broad absorption band ranging from 850 to 1000 nm in the absorption spectrum, which is well matched with the emission wavelength of a laser diode. A broad emission spectrum ranging from 927.95 to 1102.7 nm was observed under the excitation of 895 nm.

Optical properties of nanosized gold particles

1996 ◽  
Vol 11 (11) ◽  
pp. 2834-2840 ◽  
Author(s):  
Robert H. Doremus ◽  
Pratima Rao
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Absorption Spectrum ◽  
Absorption Band ◽  
Small Particle ◽  
Small Particle Size ◽  
Free Electrons ◽  
Gold Particles ◽  
Plasma Absorption ◽  
Good Agreement

Gold particles smaller than 2 nm in diameter were grown in glass. Their optical absorption spectrum did not show the usual plasma absorption band for gold particles; this band was spread by the small particle size. The absorption spectrum was calculated from the bulk optical properties of gold, modified for the small particle size; there was good agreement between calculated and measured spectra. The smallest particles containing from 20 to 40 gold atoms showed a λ−4 dependence of absorption on wavelength λ. This result implies that the absorption in these particles was entirely from free electrons at wavelengths above 0.3 μm.

scholarly journals THE ULTRAVIOLET ABSORPTION SPECTRUM OF PEPSIN

1934 ◽  
Vol 17 (6) ◽  
pp. 797-801 ◽  
Author(s):  
Frederick L. Gates
Keyword(s):  
Absorption Spectrum ◽  
Absorption Band ◽  
Ultraviolet Absorption ◽  
Extinction Curve ◽  
Absorption Curve ◽  
Ultraviolet Absorption Spectrum ◽  
Extinction Coefficients

The ultraviolet absorption spectrum of Northrop's pure crystalline pepsin has been determined. The curve of calculated molecular extinction coefficients is given. There is noted a general resemblance of the absorption curve for pepsin to that for urease and tyrosine; the absorption band is maximum at 2750–2800 Å.µ., minimum near 2500. A slight hump on either side of the peak of the extinction curve may be significant.

Effect of Spectrometer Resolution on Absorption Spectra

1982 ◽  
Vol 36 (1) ◽  
pp. 49-52
Author(s):  
A. K. Arora ◽  
R. Kesavamoorthy
Keyword(s):  
Absorption Spectrum ◽  
Absorption Band ◽  
Absorption Spectra ◽  
Full Width ◽  
Half Maximum ◽  
Peak Absorption ◽  
Empirical Relations

The effect of spectrometer resolution on the parameters of an absorption spectrum is studied by numerical convolution. The dependencies of observed full width at half maximum (FWHM) and peak absorption on spectrometer resolution, true FWHM and peak absorption of the absorption band is obtained. The observed dependencies are explained qualitatively. Over the useful range of parameters, coupled empirical relations are obtained which estimate the parameters of the true spectrum from the parameters of the observed spectrum within 1.5%. The usefulness of the coupled empirical relations is demonstrated by applying them to C—H stretching mode of CHCl3.

scholarly journals On the mechanism of the absorption spectra of solutions

1909 ◽  
Vol 82 (558) ◽  
pp. 606-611 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Absorption Band ◽  
Absorption Spectra ◽  
Light Wave ◽  
Equation Of Motion ◽  
Granular Structure ◽  
The Body ◽  
Transparent Medium ◽  
Polarised Light

On the theory of electrons the colour of bodies is explained in three ways: (1) The body is homogeneous and the electrons in it execute vibrations about their mean position in the molecules. (2) The body is homogeneous and the electrons in it are free to move about from molecule to molecule as is the case with metals. (3) The body may consist of small spheres or grains of colouring matter embedded in a homogeneous transparent medium. We get an absorption spectrum with bands in it from (1) and (3), but not from (2). We can distinguish (3) from (1) by the polarised light scattered by the grains; the quantity of light scattered is, however, small in comparison with the quantity absorbed in the grains. The granular structure is also revealed by ultramicroscopic examination. This investigation is concerned only with (1). An absorption band, then, corresponds to a principle oscillation of the molecule or whatever system the absorption spectrum is characteristic of. Let the principal co-ordinates of this system be q 1 , q 2 ... q n ; Then, when a light wave is being transmitted across the medium, if the motion is not damped, the typical equation of motion assumes the form.

Sign in / Sign up

Export Citation Format

Share Document