Experimental studies of fundamental excitations in conjugated polymers are interpreted within the framework of current theoretical electronic structural calculations and physical structure characterizations. The instabilities peculiar to this class of materials that are responsible for their departure from metallic behavior are identified explicitly. [Pg.449]

Within the harmonic approximation, only fundamental excitations—Av, = + 1, Av,- = 0 (J 0—of excitation energy hvt are allowed. [Pg.703]

Within these three tensors final Stephens and Devlins equations for the rotatory strength Pgigo(i) of the fundamental excitation of i-th mode is the following [82] [Pg.462]

With broad-band pulses, pumping and probing processes become more complicated. With a broad-bandwidth pulse it is easy to drive fundamental and overtone transitions simultaneously, generating a complicated population distribution which depends on details of pulse stmcture [75], Broad-band probe pulses may be unable to distinguish between fundamental and overtone transitions. For example in IR-Raman experiments with broad-band probe pulses, excitation of the first overtone of a transition appears as a fundamental excitation with twice the intensity, and excitation of a combination band Q -t or appears as excitation of the two fundamentals 1761. [Pg.3040]

Equation (25) holds for monodisperse samples with a single diffusion time constant t, and the diffraction efficiency in response to the most fundamental excitation, a step function where the grating amplitude is switched from 0 to 1 at f = 0, is [27,28,35,45] [Pg.20]

Fig. 2.2 Interaction between light and matter showing the approximate energies of fundamental excitations |

There exists an extensive literature on theoretical calculations of the vibrational damping of an excited molecule on a metal surface. The two fundamental excitations that can be made in the metal are creation of phonons and electron-hole pairs. The damping of a high frequency mode via the creation of phonons is a process with small probability, because from pure energy conservation, it requires about 6-8 phonons to be created almost simultaneously. [Pg.24]

Fig. 6. Similar plot as Fig. 3 for a nontotally symmetric (and hence undisplaced, B = 0) harmonic oscillator involved in weak vibronic (i.e., Herzberg-Teller) coupling (K = , = 20) between states with perpendicular, unit transition moments. The upper half of the graph depicts the depolarization ratio, which shows dispersion in this case. The u = 1 (fundamental) excitation profile shows a pair of bands corresponding to the 0-0 and 0 1 absorption bands and the depolarization ratio peaks sharply between them, a pattern referred to as a Mortensen doublet. |

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