Mystery band

FIGURE 13. Franck-Condon envelopes of the low-energy part of the PE spectra of (a) butatriene 158 and (b) tetradeuteriobutatriene 159. The central feature labeled 1 is the mystery band mentioned in the text... 

In certain highly substituted derivatives of ethylene, like tetramethyl [117-120], or di-, tri-, and tetrafluoroethylenes [121] there is a well pronounced band at frequencies lower than that of the singlet N —> Vband. For some time the origin of these bands was unknown and in a semihumoristic manner they were called the mystery band . At present we know that these are just the (n, 3s) Rydberg bands which for such molecules pass to the low frequency side of the (n, 7t ) band. 

The majority of photochemistry of course deals with nondegenerate states, and here vibronic coupling effects are also found. A classic example of non-Jahn-Teller vibronic coupling is found in the photoelectron spectrum of butatriene, formed by ejection of electrons Irom the electronic eigenfunctions (approximately the molecular orbitals). Bands due to the ground and first excited A B2u states of the radical cation are found at energies predicted by calculations. Between the bands, however, is a further band, which was termed the mystery band [169]. This band was then shown to be due to vibronic coupling between the states [170]. 

Fig. 6.1 Comparison of the experimental photoelectron spectrum of butatriene with the full theoretical result and the one obtained in the Condon approximation with uncoupled PESs (from left to right). The band V in the left panel was termed mystery band ...

Cederbaum LS, Domcke W, Koppel H, von Niessen W (1977) Strong vibronic coupling effects in ionization spectra the mystery band of butatriene. Chem Phys 26 169... 

The number of turnovers (10) in hydrocarbon production without apparent decrease in activity proved that the reaction was indeed catalytic. The IR spectrum of the recovered resin showed small absorptions due to CpCo(C0)2 5 due to some recar bony la-tion of " CpCo". In addition, a broad distinct band at 1887 cm"l was seen. The identity of the species exhibiting this carbonyl band is still a mystery in particular, the band position does not match that reported for any of the CpCo (CO) 2 -derived di- and trinuclear carbonyls (vide supra). It is tempting to associate this band with seme catalytic intermediate, such as the polymer-bound analogues of CpCo(H)2(C0) and CpCo(HKPh)(CO), but this is pure speculation. 

Figure 1.1 Rick Allen, the drummer for die rock band Def Leppard, lost his arm in an automobile accident. He reports that, at the time of the accident, he did not feel any pain. Preventing the feeling of pain under extreme circumstances is just one of the mysteries of the brain and the body.

The behavior of cationic intermediates produced in styrene and a-methyl-styrene in bulk remained a mystery for a long time. The problem was settled by Silverman et al. in 1983 by pulse radiolysis in the nanosecond time-domain [32]. On pulse radiolysis of deaerated bulk styrene, a weak, short-lived absorption due to the bonded dimer cation was observed at 450 nm, in addition to the intense radical band at 310 nm and very short-lived anion band at 400 nm (Fig. 4). (The lifetime of the anion was a few nanoseconds. The shorter lifetime of the radical anion compared with that observed previously may be due to the different purification procedures adopted in this experiment, where no special precautions were taken to remove water). The bonded dimer cation reacted with a neutral monomer with a rate constant of 106 mol-1 dm3s-1. This is in reasonable agreement with the propagation rate constant of radiation-induced cationic polymerization. 

Franz s encounter with his mysterious host, the underground palace, the blindfold, his initiation to hashish, the visions he experienced, and his dream-like impressions are all calculated to hold the reader s interest. They are examples of Dumas s expertise as a storyteller. And they are also examples of Dumas s subtle and masterful craftsmanship, for what the reader has actually been treated to is a rendering of Marco Polo s story of the Old Man of the Mountain and his band of Assassins. 

Thus, based on the results presented here, the presence of carbons that are irradiated by energetic ions in space very likely produces carbynoid structures. These could play a role in explaining one of the oldest mysteries in the study of the interstellar medium, namely the identifications of species responsible for the so-called diffuse interstellar bands, a forest of absorption lines seen in many directions of the sky. In fact, among the many suggested materials, linear carbon chains seem to be among the most promising (see e.g. References 2-4.)... 

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