Tetracene functionalization

Jones Jackson of Picatinny Arsenal (Ref 6) carried out experiments using the same procedure as that of Ubbelohde et al (Ref 4) except that a Cu rather than an Al sample holder was used. They performed two types of experiments a) measurements of the induction period as a function of temp for several common expls and b) examination of these expls to det which of them show the "memory effect . Jones Jackson reported that the memory effect is not found with all primary expls (eg Tetracene) and it is found with some HE s, but not all. Some of the props which might... 

Uses Can be used in detonators when initiated by another primary expl and functioning as an intermediate booster or when mixed with another primary exp to increase the sensitivity of the latter to flame or heat. Its mixture with LA was patented by Dynamit AG (Ref 8) for use in explosive rivets. Tetracene can also be used in primer caps where as little as 2% in the compn results in improved uniformity of percussion sensitivity... 

Fig. 15. Spectra of internal energy losses for photons, exceeding the work function in layers of (a) anthracene and (6) tetracene.

Fig. 6, and the results for numerous dopants in anthracene compared with calculated trap depths are given in Fig. 7. One notes that the general agreement is good considering the often approximate values of Ic and Ac available and also that particular impurities, notably tetracene, may function both as electron and positive hole traps of depths 0.17 eV and 0.42 eV respectively.

Fig. 14.28 Functionalization strategies for tetracene, leading to a variety of potential Jt-stacked arrangements.

There are many patents listed in which the pyrophoric alloy replaces the function of both lead styphnate and tetracene. One of the most sensitive mixtures was ... 

Figure 34 The relative fluorescence intensity plotted as a function of temperature, for crystalline tetracene (see Ref. 200), rubrene (see Ref. 201) and tetracene doped with pentacene green and red emission component as shown in the inset) (see Ref. 202).

Figure 35 Relative fluorescence efficiency as a function of the quantal exciting intensity for a 200 pm-thick tetracene crystal excited with the 325 nm line of a He-Cd laser. The increasing segment shows the triplet—triplet fusion contribution to the fluorescence (delayed fluorescence) the decrease at high excitation levels is attributed to quenching of the singlets by singlet-triplet annihilation. Experimental data are represented by points, theoretical fits, as described in text, by the solid line. Adapted from Ref. 206.

Figure 42 Magnetic field dependence of prompt and delayed fluorescence intensities in a tetracene crystal as a function of the magnetic field strength (a) and field orientation (b) at different temperatures. The curves in part (a) have been obtained with the field oriented at 20° with respect to the 6-axis in the a6-plane of the crystal, corresponding to one of the resonance directions shown in part (b) presenting the MFE anisotropy with the magnetic field B = 0.4T rotated in the (a6)-plane of the crystal. From Ref. 192. Copyright 1970 American Physical Society.

Figure 155 The EL intensity as a function of the measured current in neat (a) and doped (b) aromatic crystals. The three curves in part (a) are obtained for three different origin tetracene crystals of thickness 16.5 pm (I), 118 pm (II) and 19.5 pm (III). The data for the tetracene-doped anthracene and pentacene-doped tetracene crystals are shown in part (b), where the EL intensity was measured at host and guest emission bands (445 nm for anthracene, 598 and 575 nm for tetracene and 620 nm for pentacene) the near curve numbers denote the slopes of the straight-line log-log plots. Adapted from Ref. 51.

Figure 156 A comparison of the magnetic field effects on the EL (curves B and C) of tetracene crystals with (a) low and (b) high DEL component (crystals II and I, respectively, from Fig. 155a). The change of photoluminescence (PL) as a function of B is shown by the broken line (curves A). The effect was measured in two different wavelength regions A and B in the red edge and A and C in the short wavelength and emission maximum. No difference in the shape of field evolution of PL was observed. Reprinted from Ref. 287. Copyright 1975 with permission from Elsevier.

The photopolymerization of the polymers studied is influenced by the sensitizer as well as the intensity of light used. Aromatic hydrocarbons, like anthracene and tetracene, are used as singlet sensitizers whereas 1-chlorothioxanthone (CTX) is a triplet sensitizer. From the comparison of the polymerization rates of the systems studied as a function of sensitizer it follows that there is a dependence on the type of sensitizer. As seen from Fig. 2, CTX as triplet sensitizer has been found to be the best sensitizer for vinyl ether systems. 

Figure 52. Plot of the stretch exponent (5A of the probe correlation function against the ratio, T /i g, of the probe correlation time to the host a-relaxation time t / . T/PS denotes the probe tetracene (T) in the host polystyrene (PS). Other probes are anthracene (A), BPEA, rubrene (R), and the PS spheres (PS-ONS). The other hosts are polysulfone (PSF), tri(naphthal benzene) (TNB), orhto-terphenyl (OTP), polyisobutylene (PIB), and phenylphthalein-dimethylether (PDE).

The electron affinities of the aromatic hydrocarbons have been calculated using Huckel theory and MINDO/3 procedures. The electron affinities of benzene, naphthalene, anthracene, and tetracene have been calculated by density functional and ab initio procedures [8]. The relationship between the experimental and calculated values is examined. The electron affinities of other organic compounds have been calculated using MNDO, density functional, and ab initio procedures [9]. A more thorough discussion of these experimental and theoretical methods can be found in Electron and Molecule Interactions and Their Applications, Volume 2, Chapter 6. The experimental and theoretical electron affinities of atoms, molecules, and radicals up to 1984 are listed but not evaluated [10]. The NIST site briefly discusses the various methods for determining electron affinities and gives an... 

The lack of ordering is not at all surprising since the interaction between adsorbed tetracene molecules seems to be repulsive. This is in no contradiction with the bulk structure of tetracene, because in the three-dimensionally ordered structure the attraction occurs between molecules which are tilted with respect to each other (a so-called herringbone structure), such that hydrogen-terminated edges of one molecule point toward the 7i-system of the other [70, 71]. On the surface the molecules are forced into a co-planar orientation, with the result that their interaction becomes repulsive while it is not clear whether the repulsion is due to direct or substrate-mediated intermolecular interaction, it is clearly related to co-planarity and the absence of functional groups. 

Photoemission from excited single states produced by photoionization of anthracene crystals occurs after two step laser excitation Biphotonic excitation of phenanthrene under 208 nm irradiation is a complex process involving both ionization andT-T annihilation. Change transfer exciton band structures have been characterized with samples of crystalline tetracene . Measurement of the photoionization efficiency in trans-stilbene crystals as a function of excitation energy shows that ionization occurs after rapid vibronic relaxation o. 

FIGURE 1.1.5 Evolution of the INDO-calculated electronic splittings of the HOMO and LUMO levels in a cofacial dimer made of two tetracene molecules as a function of the intermolecular separation. 

O. Ostroverkhova, D. G. Cooke, F. A. Hegmann, J. E. Anthony, V. Podzorov, M. E. Gershenson, O. D. Jurchescu, and T. T. M. Palstra. Ultrafast carrier dynamics in pentacene, functionalized pentacene, tetracene, and rubrene single crystals. Applied Physics Letters, 88(16) 162101-3, 2006. 

As one may deduce from Table 1, the computational cost of full-direa MP2 calculations grows with the fifth power of the number of basis functions. The timings given in Table 1 are for runs constrained to 14 MW of the core memory. Decreasing the size of the core memory to 7 MW would result in a doubling of the CPU time for calculations on benzene, naphthalene, and anthracene. Calculations on tetracene and pentacene would not run with this amount of the core memory. 

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