Light electronic spectra

The stability of C60 and C70 solutions in vegetable oils has been examined also towards the action of UV light. A C60 solution in linseed oil has been irradiated in a quartz reactor with UV light from a 12 W low-pressure Hg lamp having its main emission at 254 nm under N2. In less than 1 hour irradiation, all the visible part of the electronic spectrum of C60 with bands at about 530 and 600 nm have been bleached. Simultaneously, a growth in absorption intensity as function of the irradiation time has been observed at about 410nm. 

O-Donor ligands. The pyroxene NaTiSi206, synthesized at high pressure (65 kbar) and temperature (1550 °C), is obtained as light-green crystals when quenched to room temperature. A-Ray studies showed that the crystals are of the NaM SijOg structural type, and the diffuse reflectance electronic spectrum confirmed that this is one of the few oxides known to contain Ti . ... 

Irradiated 2-methyltetrahydrofuran glass gives an ESR signal as shown in Fig. 4, which is composed of a central sharp spectrum and a broad seven-line spectrum. The former has the width of 4.5 G and is bleached out by visible lights. This spectrum is due to the trapped electrons in the glass. 

When I observed the E luminescence shown in Figure 32, the emission not only aroused interest and excitement but also confusion, because lepidopterene, prior to 1979 always obtained as by-product in the synthesis of its isomer l,2-di-9-anthrylethane 7a, was described in the literature as nonfluorescent . Today, one may speculate as to why the E exciplex luminescence discussed in Section V.B has evaded earlier discovery. With the benefit of hindsight, I presume that lepidopterene previously never got photoexcited. Its electron spectrum (see Figure 32) simply precludes the absorption of light through ordinary laboratory glassware. 

The enzyme contains six identical subunits (M = 96600) arranged in the form of an octahedron. Each subunit contains two tightly bound nickel ions (% nickel = 0.12). After the electronic spectrum of the enzyme has been corrected for light scattering the d-d bands associated with nickel(II) at 407, 747 and 1060 nm are consistent with nickel in an octahedral environment. In the presence of acetohydroxamic acid the... 

VO(tpp)-CH3OH, is slightly soluble in CHC13 and CH2C12, less soluble in pyridine, and insoluble in water and alcohols. The material is stable in the solid state and stable in solution when protected from the light. The electronic spectrum contains bands at 423, 508, 547, and 581 nm with molar absorptivities of 50,100, 4900, 22,500 and 4160, respectively. 

Several reasons were proposed to explain the cleaner chemistry. First, the electrostatic fields (0.3 and 0.9 V for Na-Y and Ba-Y, respectively) in the zeolite stabilize the hydrocarbon-02 charge transfer, thereby shifting the transition to visible wavelengths. Second, the use of visible excitation suppresses the secondary photochemistry rampant with UV light. Third, the steric constraints imposed by the zeolite promote product selectivity. This chemistry can be demonstrated by the reaction of 2,3-dimethyl-2-butene (DMB). Figure 26a shows the electronic spectrum... 

Fig. 4.3. (D and E) Primary electron acceptor (A 12) electron acceptor X. (D) Light>dark spectrum of the electron acceptor X in PSI-RC, recorded at 5°C and —0.62 V — the broad band at 450-550 nm is attributed to an FeS center and the other changes to electrochromic effects (from Ref. 57). (E) ESR spectrum of X in PSI-RC, measured at 10 K (from Ref. 290).

When the vibronic structure in the electronic emission or absorption spectra are not well enough resolved to analyze as above, Raman data must be used in combination with the electronic spectra. The most efficient method of obtaining the distortions will be to use a pre-resonance Raman spectrum in conjunction with the electronic spectrum. (In the pre-resonance Raman experiment the exciting light is detuned just off resonance.) The pre-resonance Raman spectrum corresponds to short time dynamics and a big damping factor (Section III.F.l.c). In the short time limit, the intensities in the Raman spectrum are related to the displacements by Eq. (12). In the short time limit, the absorption spectrum becomes [42]... 

The polarized electronic spectrum of the diamagnetic Ni(DPM)2 displays three d-d transitions hidden under a broad band envelope, with energies at 16,000, 18,500, 20,000 cm 1 which could only be resolved using polarized light with... 

Fig. 9. Electronic spectrum of Jo measured in stretched polyethylene film with light parallel...

When the colourless crystal in the LIESST-generated HS state is subsequently irradiated by a monochromatic red light of v= 12200 cm-1, the excited state 5E of the HS complex is generated. Its decay proceeds through the SE 37 1 - 1 A pathway and results in the reappearance of the purple LS system. This is referred to as the reverse LIESST effect. The electron spectrum of the reverse-LIESST-generated LS state is almost identical to that of the starting LS system at the beginning of the experiment [7]. 

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