A. P. Moravskii

Rotational reorientation dynamics of C60 in various solvents. Picosecond transient grating experiments

Abstract The picosecond transient grating technique has been used to study the rotational reorientation of C 60 in various solvents: in toluene 7± 1.5 ps, o -dichlorobenzene 10.3± 1.5 ps, o -xylene 13±2 ps and in decalin 3.5± 1.5 ps. The data obtained cannot be described by hydrodynamic Debye theory. Rough-sphere fluid theory predicts the correct values for C 60 rotation in toluene, o -dichlorobenzene and in decalin. The deviations for o -xylene are probably connected with the specifics of the local solvent structure or with the stronger interaction of C 60 with solvent molecules. The rotation of C 60 in decalin is rapid and approaches the rotation in the gas phase determined by inertia.

Photophysical properties of C@60: picosecond study of intersystem crossing

Abstract The picosecond transient absorption spectrum of C 60 in toluene was obtained in the region 420-1100 nm and a new transient absorption band near 1000 nm was discovered. This band was attributed to the S 1 —S x transition, probably between configurations (h u ) 9 (t 1g ) 1 ← (h u ) 9 (t 1u ) 1 . The intersystem crossing time τ= 830±190 ps was estimated from the S 1 —S x absorption decay and from the creation of the T 1 -T x absorption band.

Photochemical properties of C60. Triplet-excited C60 quenching by electron acceptors TCNQ and TCNE in solution. Laser photolysis study

Abstract The quenching of triplet-excited 3C60 by electron acceptors TCNQ and TCNE has been established in nonpolar toluene and moderately polar benzonitrile solutions. The quenching constants kq are 5.5 × 109 in toluene, 2.2 × 109 in benzonitrile for TCNQ and 7.9 × 105 in toluene, 4.2 × 108 (M s)−1 in benzonitrile for TCNE. The 3C60 quenching can be explained by triplet exciplex formation. The time-resolved spectra of the C60/TCNE system exhibit a well pronounced charge-transfer excited state [Cδ60 … TCNEδ−] in benzonitrile.

Orientational behavior of C70 molecules in chlorobenzene

Abstract The orientational behavior of C 70 singlet excited molecules in a chlorobenzene solution has been measured at room temperature by the picosecond transient grating technique. A two-stage decay signal was observed: a fast part ( τ = 12 ± 5 ps) which is comparable with the corresponding signal of C 60 in chlorobenzene ( τ = 8 ± 2 ps), and a slow part ( τ = 30 ± 5 ps). The data obtained are analyzed in terms of the rotation of C 70 molecules. The influence of the dielectric friction on the C 70 rotation is reported.

INTERACTION OF PLATINUM FULLERIDE C60PT WITH DEUTERIUM

X-ray photoelectron spectra and catalytic properties of platinum fulleride C60Pt were studied. The value of the bond energy of Pt4f7/2 (72.4 eV) found for platinum in the starting C60Pt suggests a partial charge transfer from Pt to C60. The interaction of solid platinum fulleride with gaseous deuterium leads to the formation of fullerene deuterides C60Dx and Pt clusters.

Hydrogenation of fullerites in the presence of intermetallic compounds or metals

Fullerene hydrides containing 24–26 H atoms per fullerene molecule were obtained by hydrogenation of solid-phase mixtures of fullerenes with either intermetallic compounds LaNi5, LaNi4.65Mn0.35, CeCo3 or V and Pd metals with gaseous hydrogen at 1.0–2.5 MPa and 573–673 K. These fullerene hydrides decompose at 800 K with evolution of H2. Upon subsequent heating to 1000 K, vanadium reacts with fullerene to yield a cubic phase of vanadium carbide. The intermetallic compounds react with fullerene with the formation of a metallic phase of the 3d-metal and destruction of fullerene. Palladium does not react with fullerene.

Vibrational Spectra of C60Hx with 36⩽x⩽60 and Emission/absorption of Some Interstellar Clouds

Optical transmission spectra of C60Hx with x in the range 36–60 show an increase of the molecular symmetry at x = 60. Hydrogenated fullerenes C60 were synthesized at a hydrogen pressure of 50±5 kbar and temperatures up to 773 K. Combination of the vibration modes of C60H60 and, for example, C60H48 may explain the emission and absorption spectra of some interstellar and circumstellar clouds.

Synthesis of a C60 complex withN,N,N′,N′-tetramethyl-p-phenylenediamine and its crystal structure

The complex of fullerene C60 withN,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD) was synthesized and studied by X-ray analysis.

Orientational dynamics of C70 molecules in chlorobenzene

Dynamics of anisotropy relaxation of C70 singlet excited molecules in chlorobenzene was measured at room temperature by the picosecond transient grating technique. The time-ependent diffraction efficiency exhibits a two-stage decay: a fast component (τ1 = 12±5 ps), which is comparable with the corresponding signal of C60 in chlorobenzene (τ = 8±2 ps), and a slow one (τ2 = 30±5 ps). It is supposed that relaxation of anisotropy is related to the orientational mobility of excited C70 molecules relative to two axes of the molecular framework. The results obtained cannot be described by the Einstein-Stokes-Debye theory. The Hynes-Kapral-Weinberg theory, which takes into account microscopic interactions between molecules upon collisions, agrees satisfactorily with the experiment. The influence of dielectric friction on the orientational mobility of C70 in chlorobenzene was estimated.

Influence of conditions for preparation of fullerene-containing carbon black on its microwave properties and yield of fullerenes

Conditions for preparation of the fullerene-containing carbon black with the maximum yield of fullerenes were determined. A correlation between the dielectric constant of the carbon black in the microwave range and the yield of fullerenes was found. The relation of the fullerene-containing carbon black structure to the conditions of its preparation and dielectric constant are discussed.