THE ABSORPTION SPECTRUM OF DIPHENYLENE IN THE NEAR-ULTRAVIOLET

1961 ◽  
Vol 39 (4) ◽  
pp. 765-772 ◽  
Author(s):  
Robin M. Hochstrasser
Keyword(s):  
Absorption Spectrum ◽  
Band Structure ◽  
Theoretical Prediction ◽  
Intensity Distribution ◽  
Room Temperature ◽  
Excited Level ◽  
Vibrational Structure ◽  
Infrared Band ◽  
Weak Absorption ◽  
Near Ultraviolet

The absorption spectrum of diphenylene has been measured in the vapor at a variety of temperatures, in solution at room temperature, and in an EPA rigid glass at 90 °K. From a consideration of the band structure and intensity distribution it was concluded that the weak absorption at 25,041 cm−1 (vapor; ƒ ≈ 10−3) is due to a symmetry-forbidden electronic transition. The theoretical prediction that the excited level is of species B1g was supported by the presence of a strong infrared band at 732 cm−1 corresponding to observed perturbing vibration of frequency 792 cm−1. The solution spectrum was found to exhibit a vibrational structure typical of a g–g forbidden excitation.

The Near-ultraviolet Absorption Spectrum of Diimide in Liquid Ammonia and its Decomposition between −65 and −38 °C

1974 ◽  
Vol 52 (13) ◽  
pp. 2513-2515 ◽  
Author(s):  
R. A. Back ◽  
C. Willis
Keyword(s):  
Absorption Spectrum ◽  
Gas Phase ◽  
Room Temperature ◽  
Liquid Ammonia ◽  
Vibrational Structure ◽  
Ultraviolet Absorption ◽  
Ultraviolet Absorption Spectrum ◽  
First Order ◽  
Rapid Decomposition ◽  
Near Ultraviolet

The near-ultraviolet absorption spectrum of diimide in liquid ammonia at −50 °C is shifted about 500 Å to the red compared with the gas-phase spectrum, with λmax = 4000 Å. The spectrum is also broadened and the vibrational structure largely obscured. It is suggested that hydrogen bonding is responsible for these changes.Diimide is much more stable in liquid ammonia between −65 and −38 °C than in the gas phase at room temperature. A first-order decay is observed with Arrhenius parameters of A = 1.9 × 103 s−1 and E = 6.6 kcal/mol; this is always preceded by a more rapid, higher-order initial decay which may be related to the rapid decomposition observed during vaporization.

THE CRYSTAL SPECTRUM OF PERYLENE

1961 ◽  
Vol 39 (3) ◽  
pp. 451-458 ◽  
Author(s):  
Robin M. Hochstrasser
Keyword(s):  
Absorption Spectrum ◽  
Electronic Absorption ◽  
Weak Coupling ◽  
Room Temperature ◽  
Excited Level ◽  
Vibrational Structure ◽  
Factor Group ◽  
Electronic Band ◽  
Dipole Interactions ◽  
Induced Dipole

The electronic absorption spectrum of crystalline perylene has been examined in the spectral region 3000–4700 Å. The lowest energy electronic state of perylene has a large oscillator strength and the crystal spectrum deviates considerably from that calculated from a weak coupling (Davydov) model.The sublimation flakes were examined at room temperature and at the temperature of boiling nitrogen. The lowest energy crystal state was polarized along the crystallographic a-axis (Bu) and the factor group splitting of lowest vibrational envelope of the electronic band was 800 cm−1. The whole spectrum was more intense along the a- than along the b-axis of the crystal. These results are consistent with the notion that the crystal spectrum is derived from dipole-induced dipole interactions between molecular B2u levels of perylene and neighboring unexcited molecules. This assignment of the lowest excited level of perylene is in agreement with theory.The molecular vibrational structure is severely altered in the crystal and the observed crystal shift is much smaller than that predicted by the Davydov theory.

Near Ultraviolet Absorption Spectra of cis and trans Acrolein and Acrolein-d1

1973 ◽  
Vol 51 (11) ◽  
pp. 1170-1175 ◽  
Author(s):  
G. A. Osborne ◽  
D. A. Ramsay
Keyword(s):  
Absorption Spectrum ◽  
Absorption Spectra ◽  
Vibrational Structure ◽  
Ultraviolet Absorption ◽  
Additional Information ◽  
Near Ultraviolet ◽  
New Information ◽  
Path Lengths ◽  
Cis And Trans

The absorption spectrum of acrolein-d1 (CH2=CH∙CDO) has been studied in the region 3900 to 4400 Å with path lengths and pressures up to 10 m atm and temperatures from 25 to 160 °C. This study provides additional information for the interpretation of the vibrational structure observed in the 3A″–1A′ (trans), 1A″–1A′ (cis), and 3A″–1A′ (cis) systems of acrolein, in addition to new information for acrolein-d1. Most of the features in these spectra are now assigned.

Notizen:Phosphorescence Decay in Thallium-Doped Ammonium Chloride

1978 ◽  
Vol 33 (10) ◽  
pp. 1241-1242 ◽  
Author(s):  
S. Chaudhari ◽  
T. R. Joshi ◽  
R. V. Joshi
Keyword(s):  
Aqueous Solution ◽  
Ammonium Chloride ◽  
Mechanical Treatment ◽  
Room Temperature ◽  
Host Lattice ◽  
Luminescence Decay ◽  
Decay Rates ◽  
Negative Ion ◽  
Ultraviolet Emission ◽  
Near Ultraviolet

Abstract The phosphorescence decay rates of thallium-doped ammonium chloride (NH4Cl:Tl) phosphors, prepared by crystallization from aqueous solution, have been studied at room temperature for near-ultraviolet emission. The effects of impurity concentration as well as thermal and/or mechanical treatment on the decay rates have been examined. Phosphorescence centres consisting of a Tl+ion and a nearby negative ion vacancy are suggested to be responsible for the observed luminescence decay. The changes in the decay characteristics after pretreatments are explained on the basis of the location of the centres in normal and distorted regions of the host lattice.

Room-temperature near-ultraviolet electroluminescence from a linear silicon chain

1997 ◽  
Vol 71 (23) ◽  
pp. 3326-3328 ◽  
Author(s):  
Chien-Hua Yuan ◽  
Satoshi Hoshino ◽  
Seiji Toyoda ◽  
Hiroyuki Suzuki ◽  
Michiya Fujiki ◽  
...  
Keyword(s):  
Room Temperature ◽  
Near Ultraviolet
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