Absorption spectra of anthracene

Fig. 14. Sn So and Tm t- Tl absorption spectra of anthracene in alcohol at 113 K (From Meyer, Astier, and Leclercq, Ref. O))...

Figure 15 (1) UV absorption spectra of anthracene, phenazine and acridine in ethanol. (2) UV absorption spectra of anthracene, and 1- and 2-azaanthracene in ethanol (Reproduced with permission from (51JCS3199))...

Figure 24 The CT absorption band in solid anthracene-trinitrobenzene complex (1). Solid state absorption spectra of anthracene (2) and trinitrobenzene (3) are shown for comparison. After Ref. 109.

Figure 1.8. Absorption spectra of anthracene (—) and phenanthrene (—) (by permission from DMS-UV-Atlas 1966-71).

FIGURE 2.15. Absorption spectra of anthracene in a liquid crystalline matrix [29]. 

The luminescence properties of anthracene and its derivatives provide an excellent illustration of the relation between the excited state distortion and the profile of the luminescence spectra. Figure 6 shows the luminescence and absorption spectra of anthracene. Note that the extinction coefficient for the singlet-singlet transition is 8 orders of magnitude higher than the value for the singlet- triplet transition. 

Figure 6. UV-Vis absorption spectra of anthracene solutions in DCM a) initial solutions of different concentrations b) 1 mM initial solution (black curve) and remaining solution (red curve).

Kira and coworkers25 found that in deaerated DMSO solution of frans-stilbene both the solute cation and anion are produced and the anions are eliminated by aeration. Since they found26 that the absorption spectra of the anthracene cation and anion are quite similar, they suggested25 that the absorption spectrum observed by Hayon for anthracene solution in DMSO is a superposition of the spectra of the solute cation and anion. This observation casts a serious question on the yield of solvated electrons found by Hayon23. 

Fig. 12 (a) The absorption spectra of singlet excited anthracene ( ANT ) and anthracene cation radical (ANT+ ) obtained upon 25-ps laser excitation of anthracene in the presence of excess maleic anhydride (MA). (b) The authentic spectrum of singlet excited anthracene ( ANT ). Reproduced with permission from Ref. 212. 

For instance, the absorption and emission spectra of anthracene show a wave-number spacing of about 1400 cm-1, i.e. an energy spacing of 2.8 x 10 20 J, between the 0 and 1 vibrational levels. In this case, the ratio Ni/N0 at room temperature (298 K) is about 0.001. 

Absorption and emission spectra of anthracene in solution in dioxane. 

Fig. 8 Kubelka-Munk optical absorption spectra of as-prepared mesostructured (black) and mesoporous NU-Ge-1 (red) semiconductors and NU-Ge-1 incorporating into the pores TCNE (blue) and TTF (green line) organic molecules. The recovered optical adsorption spectra of NU-Ge-1 by encapsulation of TCNE-TTF complexes are also given (dashed lines). Inset optical absorption spectrum of NU-Ge-1 encapsulating anthracene...

FIGURE 10.7 UV absorption and fluorescence spectra of anthracene in cyclohexane (adapted from Karcher et al., 1985). 

FIGURE 10.13 Absorption and fluorescence spectra of anthracene in three phases. Pronounced red shifts occur going from the vapor state to solution in dioxane to the solid state separation of the 0-0 bands also increases (adapted from Bowen, 1946). 

Chandross and Ferguson64 find that the absorption spectra of dimers, produced65 by photolytic cleavage of photodimers of anthracene and mono-derivatives in a rigid methylcyclohexane glass at 77°K, are consistent with a symmetrical sandwich configuration these dimers also emit the characteristic excimer fluorescence. On the other hand, it is necessary to assume a 60° rotation of one component about the intermolecular axis of the 9,10-di-chloroanthracene dimer (as in the crystalline compound) to account for the observed resonance splittings of both absorption bands.64... 

Figure 15.3 Electronic absorption spectra of (a) naphthalene, (b) anthracene, (c) phenanthrene, (d) 2,3-benzanthracene (naphthacene), and (e) 1,2-benzanthracene (benz(a)-anthracene) (data from Pretsch et al., 2000).

Figure 18-21 Excitation and emission spectra of anthracene have the same mirror image relation as the absorption and emission spectra in Figure 18-16. An excitation spectrum is nearly the same as an absorption spectrum. [C. M. Byron and T. C. Wemer. Experiments in Synchronous Fluorescence Spectroscopy lor the Undergraduate Instrumental Chemistry Course"...

The name lepidopterene refers to the hydrocarbon 113 (L) whose butterflylike molecular shape was first revealed by X-ray diffraction analysis [129,130]. The structured electronic absorption spectra of lepidopterenes around 270 nm closely resemble that of 9,10-dihydroanthracene (see Figure 31). However, in terms of excited state properties, lepidopterenes have very little in common with 9,10-dihydroanthracene, which in solution fluoresces with a quantum yield of 0.16. By contrast, photoexcitation of lepidopterenes leads mainly to intramolecular exciplexes of 7i-chromophorically substituted anthracenes in an adiabatic process, for which both the molecular topology... 

Figure 13.3 shows the absorption and fluorescence spectra of anthracene in ethanol for the SQ Sx transitions. Since the transitions are allowed, the intensity of light emitted is almost as strong as the intensity of light absorbed. The quantum yield for fluorescence, 8f, is defined by Equation 13.9. 

Figure 13.3 Absorption (dashed line 17.2 fig/ml) and fluorescence (solid line 1.0 jag/ml) spectra of anthracene in ethanol. From C. A. Parker and W. T. Rees, Analyst, 85, 587 (1960). Reproduced by permission of The Analyst and C. A. Parker.

Fig. 2.6. a TOF mass spectra of anthracene at 1.4- and 0.8-p.m excitations, and b the cation absorption spectrum in a low-temperature matrix with two spectra of the excitation pulses... 

Various compounds were shown to sensitize the photochemical decomposition of pyridinium salts. Photolysis of pyridinium salts in the presence of sensitizers such as anthracene, perylene and phenothiazine proceeds by an electron transfer from the excited state sensitizer to the pyridinium salt. Thus, a sensitizer radical cation and pyridinyl radical are formed as shown for the case of anthracene in Scheme 15. The latter rapidly decomposes to give pyridine and an ethoxy radical. Evidence for the proposed mechanism was obtained by observation of the absorption spectra of relevant radical cations upon laser flash photolysis of methylene chloride solutions containing sensitizers and pyridinium salt [64]. Moreover, estimates of the free energy change by the Rehm-Weller equation [65] give highly favorable values for anthracene, perylene, phenothiazine and thioxanthone sensitized systems, whilst benzophenone and acetophenone seemed not to be suitable sensitizers (Table 5). The failure of the polymerization experiments sensitized by benzophenone and acetophenone in the absence of a hydrogen donor is consistent with the proposed electron transfer mechanism. 

The transient T-T absorption in the gas phase has been measured recently for aromatic molecules such as naphthalene (119,211) and anthracene (80,81) using flash kinetic spectroscopy and tandem laser pulse absorption techniques. Particularly, the later technique (211) provides time-dependent absorption spectra of the "isolated" unrelaxed triplet molecules because of its capability for rapid monochromatic excitation and detection. It will certainly provide a wealth of Important kinetic and spectroscopic information about the evolution and decay of triplet states. Direct observation of the formation of transient hot ground-state (Sq) molecules through an internal conversion process has also been achieved with laser excitation and laser... 

Therefore, a molecule in the TICT state can be regarded as a rigidly linked radical anion-radical cation pair. Experimental proof for this expectation can be gained from transient absorption spectroscopy. In the simplest case, the absorption spectrum of the TICT excited state is expected to be the sum of the individual ion spectra. This was indeed found in a few cases, with some perturbations which can be explained by the interaction of the closely-spaced radical ions. Thus, the transient absorption spectra of DMABN [135], of DMABK (or DMABA) [137] and of BA [58] resemble the spectrum of benzonitrile and acetophenone radical anion (the absorption of the dimethyl-amino radical cation is expected to be situated in the UV region and could not be observed) and to the sum of anthracene anion and cation absorption spectra, respectively. 

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