Vibrational structure and

The vibrational structure and polarization properties of the phosphorescence spectra of testosterone and two other 4-en-3-ones indicate that excitation to the lowest triplet state causes little change in geometry/ contrary to earlier... 

L. Asplund, U. Gelius, S. Hedman, K. Helenelund, K. Siegbahn, P.E.M. Siegbahn, Vibrational structure and lifetime broadening in core-ionised methane, J. Phys. B 18 (1985) 1569. 

Palese S, Mukamel S, Miller RJD, Lotshaw WT. Interrogation of vibrational structure and line broadening of liquid water by Raman-induced Kerr effect measurements within the multi-mode Brownian oscillator model. I Phys Chem 1996 100 10380-10388. 

Ila and Ilia (Section V, B, 2), and IVa (Section V, A, 2) of the periodic system, and with transition metals (Section V,B, 1). All these metal compounds and those quinoline red dyestuffs which exist only in the form 25 by introduction of suitable substituents (e.g., Fig. 13) have analogous absorption and fluorescence spectra, with pronounced vibrational structures, and many other similar properties. This... 

Analysis of the vibrational structure and rotational contours of the LIF emission and excitation spectra offers the possibility of studying the conformational changes of the molecules and clusters upon excitation. However, the assignment of the low-frequency modes observed in the LIF excitation spectra of the investigated compounds is difficult in view of the complexity of the dialkylamino group which may... 

In the bulk, the low concentration of ground-state pairs excludes their observation by absorption. The formation of the excited-state complex, termed exciplex, is a collisional process electronic excitation of either the acceptor or the donor leads to the formation of a locally excited state (for instance, in hydrocarbon molecules, it is a nn state). During the lifetime of this state, a collision with the other partner (which is in the ground state) leads to the formation of the exciplex. This mechanism is compatible with the fact that the absorption and fluorescence excitation spectra of the system are identical with those obtained by superimposing the spectra of the individual components. At the same time, the fluorescence emission spectrum changes drastically—a broad band, red shifted with respect to the bare molecule s emission spectrum, appears. It is usually devoid of vibrational structure, and is shifted to longer wavelengths as the solvent polarity increases [1],... 

It was quite interesting that naphthalene-diene compounds (-)-22, (-t-)-23, (-)-24, and (-)-25 exhibited much stronger CD Cotton effects than other halenaquinol derivatives. For example, the UV spectrum of rra j-methoxysilyl ether (-)-22 shows two intense n- K bands (Figure 4) the broad band at 324 nm (e 27 000) with complex vibrational structures and the sharp band at 218 nm (e 42 000). In... 

The assignment of band B Fig. 17.13(B) to ionization from a t(CO) orbital is uncontroversial, and is supported by calculations, vibrational structure, and comparison with spectra of COHj. Bands C-H of COFj have been assigned by direct reference to ionization energy calculations. Empirical observations are of little help here as (a) the bands overlap,... 

In a given series of olefins, the absorption intensity at the absorption maximum seems to increase with increasing symmetry of the molecule20. Thus, the intensity increases in the senes 4-methyl-f/my-2-pentene < tram-2-hexene = /ra w-2-pentene < toms-2-butene < ftm -3-hexene. The vibrational structure and the absorption intensity of the bands decrease in solution... 

Since the development of photoelectron spectroscopy by Turner and Al-Jabory, (1962), continual efforts have been invested to improve the spectral resolution. In the beginning, the resolution was sufficient to resolve vibrational structure and, by 1970, resolution of 80 cm-1 has been obtained by Edqvist et al, (1970). The first photoelectron spectrum in which partial rotational structure was revealed was reported by Asbrink for H2 (1970). But 80 cm-1 resolution only permits observation of the rotational structure of H2 (Pollard et al., 1982) and high rotational levels of heavier molecules, such as NO, because the rotational spacing increasing as 2B+J+, where B+ is the rotational constant of the ion (Wilson et al, 1984). 

Well-known luminescent ions in this class are Tl , Pb, Bi " (all 6s ), and Sn, Sb " (both 5 ). The influence of the host lattice can be illustrated by comparing Cs2NaYCl6 Bi + where the emission consists of a narrow band with considerahle vibrational structure and a small Stokes shift (800 cm ) and LaP04 Bi " where the emission consists of a broad band without any structure at all and with a large Stokes shift (19200 cm ). Table 3.3 shows that the Stokes shift varies one order of magnitude which is rather exceptional [23]. Figure 3.20 gives a spectral illustration. 

Ultraviolet Raman resonance (UVRR) spectroscopy provides for chemical species identification from both the characteristic vibrational structure and electronic spectra. The resonance enhancement also increases the absolute sensitivity of detection, making it easier to detect the structures. The advantages of UVRR spectroscopy are high sensitivity, lack of fluorescence and suitability for use in aqueous solutions. 

The benzene radical cation (Bz+) represents a prototype organic radical cation and has been studied extensively in the literature, both theoretically and experimentally. We mention early and more recent studies of its electronic structure,the photoelectron spectrum of benzene, including its vibrational structure and the high-resolution... 

Electron tunneling would be very fast and depend negligibly on temperature if only electronic motion is involved. An equally important contributor to the rate is the nuclear factor, which depends on how much the molecular structure is changed during ET. The nuclear factor depends on vibrational structure and hence on temperature. In fact, the nuclei find an activation barrier in their motion due to ET. Also, in this case we may talk about tunneling through a barrier, or nuclear tunneling. 

See Fig. 2-4 for the geometrical relationships in a two-dimensional analog of the three-dimensional stress-strain condition. So far the discussion of stress-strain relationships has been on static stress conditions. Cyclical stresses such as are applied in the operation of machine parts, in vibrating structures, and in the rapid flexing of structures that occurs in vehicles produce a different set of stress response problems. 

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