A study of the photoexcited triplet state of Cm (3C,5,9 in liquid solution (toluene, methylcyclohexane) was made using pulsed-EPR techniques. The spin-lattice relaxation time ( T I ) , phase-memory time ( T m ) , and line width (Av1p) were measured as function of temperature (1 70-360 K). The results were used to analyze Some aspects of the spin dynamics of 3Cm. The data confirm earlier findings that therelaxation toward Boltzmannequilibrium is responsible for the initial growth of the signal amplitude when FT-EPR spectra are measured as a function of delay time between laser excitation and 7r/2 microwave pulse. Also, it is found that A q p -l/aTm in both solvents over the whole temperature range. This establishes that there is a negligible contribution to the line width from unresolved I3C hyperfine structure. The contribution of the electron spin-spin interaction modulated by rotational motion to the relaxation rates is analyzed. The analysis shows that the value of the zero-field splitting parameter D, which determines the magnitude of this contribution, is about an order of magnitude less than that found in rigid matrices at low temperature. A significant residual, temperature-independent, relaxation contribution is found which may stem from the rapid interconversion between triplet states that causes the reduction in D upon going from solid state to liquid solution.

Defect rich MgO nanocrystals arranged in a hierarchic three‐dimensional pore network were synthesized by using gel combustion synthesis (GCS). By adding Li to the combustion precursor, Li‐induced changes in the morphology and defect structure of MgO could be studied systematically. At low Li loadings (up to 1 wt %), the three‐dimensional pore network was resistant to temperatures up to 800 °C, even though the primary MgO nanoparticles had changed their morphology from on average 8 nm size {100} terminated nanocubes to up to 250 nm large complex polyhedral, exposing more and more {111} facets. At higher Li loadings, the primary MgO particles grow even further, to up to 500 nm, causing the three‐dimensional pore network to collapse. After describing the GCS method, detailed structural characterizations of all of the materials synthesized were conducted by means of XRD, BET and pore size analysis, and electron microscopy. IR and thermogravimetric mass spectroscopy (TG‐MS) in combination with XRD were used to investigate the formation and decomposition of carbonate species during synthesis and calcination. Diffuse reflectance UV/Vis (DR‐UV/Vis) spectroscopy was used to characterize surface defects, such as low coordinated O2− ions at edges, corners, and kinks of the MgO surface. Bulk defects were studied by using electron paramagnetic resonance (EPR) spectroscopy. Morphology and defect concentration of the Li/MgO materials were found to be strongly dependent on the fuel‐to‐oxidizer ratio used in the combustion synthesis, the Li concentration, and the calcination atmosphere.

The emissio.n spectrum o.fpo.lycrystalline [22]paracyclo.phane shows a resolved vibronic structure ~ith a 241 cm-1 pro.gressio.n at He temperatures. The dependence orthe energy or this mode upon selective deuteration in co.mbinatio.n with results from FIR and Raman spectra could be used to identify the mode as a torsional dimer vibration_ The emission spectra could be simulated assuming a linear co.upling o.fthe to.rsio.nal mode to. the electronic transitions with co.upling strengths o.f S = 10 (fluorescence) and S = I3 (phosphorescence). This co.rrespo.nds to. an· equilibrium displacement o.fthe benzene rings under electronic excitatio.n by a torsional angie of 10.6 0 (Sl) and 12..1 0 (Tl)' in addition to the small torsion in the ground state So by about 3°.

We herein report the investigation of N@C(60) exposed to laser flash excitation to exhibit the acceleration of the decay of (N@C(60))* by the encased N atom.