C_(60) and C_(70) single crystals free from solvent contamination grew from their vapour. Large C_(60) crystals up to a size of about 5 mm × 3 mm × 3 mm and C_(70) crystals about 1 mm × 1 mm × ...C_(60) and C_(70) single crystals free from solvent contamination grew from their vapour. Large C_(60) crystals up to a size of about 5 mm × 3 mm × 3 mm and C_(70) crystals about 1 mm × 1 mm × 1 mm were obtained. C_(60) crystals with fee structure showed two types of morphological faces, namely {111} and {100 },frequently with twinning on {111} face. C_(70) crystals obtained have a hop structure with a = 10. 1 andc=16. 7 DSC and X-ray diffraction analysis indicated that C(70) crystal underwent phase transition below 100 ℃ Morphological observation suggests that the growth of C(60) and C(70) single crystals is based on layer spreading mechanism.展开更多
In search of new systems with a photoexcited redox pair which exhibits a strong and stable photoinduced absorption band to understand the photophyscial and photochemical properties of electron transfer between fullere...In search of new systems with a photoexcited redox pair which exhibits a strong and stable photoinduced absorption band to understand the photophyscial and photochemical properties of electron transfer between fullerenes (C 60/C 70) and organic donor [N,N,N′,N′-tetra(p-methylphenyl)-4,4′-diamino-1,1′-diphenyl sulphide (TPDAS)], we studied characteristic absorption spectra in the near-IR region obtained from 532 nm nanosecond laser flash photolysis of a mixture of the fullerenes (C 60/C 70) and TPDAS in polar solvents. When fullerenes (C 60/C 70) were photoexcited, the rise of the radical anion of fullerenes (C 60/C 70) with the rapid decay of their excited triplet states were observed in benzonitrile. It can be deduced that the electron transfer reaction does take place from TPDAS to excited triplet state of fullerenes (C 60/C 70). The rate constants (k et) and quantum yields (Φ et) of this process have been also evaluated.展开更多
Until now,column chromatography is still the chief method for separation andpurification of C<sub>60</sub>/C<sub>70</sub>.The stationary phases used in the method can either be neutralalumina,g...Until now,column chromatography is still the chief method for separation andpurification of C<sub>60</sub>/C<sub>70</sub>.The stationary phases used in the method can either be neutralalumina,graphite,activated charcoal,or the mixture of activated charcoal and silicagel,etc.The method that uses neutral alumina as the stationary phase and hexane asthe mobile phase is the most popular and earliest used,but it has many limitations.展开更多
By using a micro\|bomb calorimeter, the standard enthalpies of combustion of C 60 and C 70 have been determined to be -(25 947.1±8.5) and -(29 956.1±8.9) kJ/mol respectively. A g.l.c. analysis indicated that...By using a micro\|bomb calorimeter, the standard enthalpies of combustion of C 60 and C 70 have been determined to be -(25 947.1±8.5) and -(29 956.1±8.9) kJ/mol respectively. A g.l.c. analysis indicated that the amounts of residual organic solvents in the samples were very small, and their effects on the final results were negligible. The energy of combustion of C 60 determined in this work is in agreement in the uncertainty interval with that determined by means of traditional calorimeter using macro amount of sample. The enthalpies of formation of these two substances have been derived. The strain energies in the molecules of C 60 and C 70 were estimated by a bond energy scheme and by using corannulene as the model compound, the results estimated from different methods are very close.展开更多
Fullerols of C 60 and of C 70 \ [C 60 (OH)\-\%n\%, C 70 (OH)\-\%m\%], water\|soluble fullerene derivatives, unlike some other fullerene derivatives (such as C 60 (C\-4H\-6O), C 60 (C\-3H\-7N) and C 60 [C(COOEt)\-2]\-\...Fullerols of C 60 and of C 70 \ [C 60 (OH)\-\%n\%, C 70 (OH)\-\%m\%], water\|soluble fullerene derivatives, unlike some other fullerene derivatives (such as C 60 (C\-4H\-6O), C 60 (C\-3H\-7N) and C 60 [C(COOEt)\-2]\-\%x\%), do not result in excited triplet state but in ionization via monophotonic process in aqueous solutions with 248 nm laser. The quantum yields of formation of hydrated electron ( Φ e - ) are determined to be 0.08 and 0.11 for fullerols of C 60 and of C 70 respectively at room temperature (ca. 15℃) with KI solution used as reference. By laser flash photolysis and oxidation of sulfate radical anion SO -· \-4, the fullerol radical cation or neutral radical of C 60 is confirmed to be existent and the transient absorption spectra of fullerol radical cation of C 70 are observed for the first time.展开更多
The spectra of Cm and Cm thin films over a wide energy range (0.6 to 6.5eV) are measured by transmission spectroscopy and photothermal deflection spectroscopy (PDS), and the optical absorption coefficients are obtaine...The spectra of Cm and Cm thin films over a wide energy range (0.6 to 6.5eV) are measured by transmission spectroscopy and photothermal deflection spectroscopy (PDS), and the optical absorption coefficients are obtained. The optical transitions for the Cm and Cw thin films are analyzed according to the molecular orbital model. The weak absorption spectra of the fullerenes are similar to that of amorphous silicon. The optical energy gaps are given by Tauc’s plots as 1.75 and 1.65eV for C60 and C70 thin films, respectively. The disorders in the fullerene films, which resulted in band-tail state or defect state, are indicated by Urbach edge and sub-gap absorption. It is the disorder that brought the difficulty in determination of the energy gap for fullerenes. The effects of the deflection medium and substrate on the weak absorption spectra of fullerene films are also discussed.展开更多
The photoinduced electron-transfer reaction of N,N,N′,N′-tetra-(p-methylphenyl)-4,4′-diamino-1,1′-diphenyl ether (TPDAE) and fullerenes (C 60/C 70) by nanosecond laser flash photolysis occurred in benzonitri...The photoinduced electron-transfer reaction of N,N,N′,N′-tetra-(p-methylphenyl)-4,4′-diamino-1,1′-diphenyl ether (TPDAE) and fullerenes (C 60/C 70) by nanosecond laser flash photolysis occurred in benzonitrile. Transient absorption spectral measurements were carried out during 532 nm laser flash photolysis of a mixture of the fullerenes (C 60/C 70) and TPDAE. The electron transfer from the TPDAE to excited triplet state of the fullerenes (C 60/C 70) quantum yields and rate constants of electron transfer from TPDAE to excited triplet state of fullerenes (C 60/C 70) in benzonitrile have been evaluated by observing the transient absorption bands in the near-IR region where the excited triplet state, radical anion of fullerenes (C 60/C 70) and radical cations of TPDAE are expected to appear.展开更多
文摘C_(60) and C_(70) single crystals free from solvent contamination grew from their vapour. Large C_(60) crystals up to a size of about 5 mm × 3 mm × 3 mm and C_(70) crystals about 1 mm × 1 mm × 1 mm were obtained. C_(60) crystals with fee structure showed two types of morphological faces, namely {111} and {100 },frequently with twinning on {111} face. C_(70) crystals obtained have a hop structure with a = 10. 1 andc=16. 7 DSC and X-ray diffraction analysis indicated that C(70) crystal underwent phase transition below 100 ℃ Morphological observation suggests that the growth of C(60) and C(70) single crystals is based on layer spreading mechanism.
基金ProjectsupportedbytheNationalNaturalScienceFoundationofChina (No .2 0 0 710 12 ) ,ResearchFundfortheYoungTeacherPro gramofHigherEducationofChina (No .2 0 0 0 6 5 )andtheNaturalScienceFoundationofGuangdongProvince (No .0 0 0 70 0 )
文摘In search of new systems with a photoexcited redox pair which exhibits a strong and stable photoinduced absorption band to understand the photophyscial and photochemical properties of electron transfer between fullerenes (C 60/C 70) and organic donor [N,N,N′,N′-tetra(p-methylphenyl)-4,4′-diamino-1,1′-diphenyl sulphide (TPDAS)], we studied characteristic absorption spectra in the near-IR region obtained from 532 nm nanosecond laser flash photolysis of a mixture of the fullerenes (C 60/C 70) and TPDAS in polar solvents. When fullerenes (C 60/C 70) were photoexcited, the rise of the radical anion of fullerenes (C 60/C 70) with the rapid decay of their excited triplet states were observed in benzonitrile. It can be deduced that the electron transfer reaction does take place from TPDAS to excited triplet state of fullerenes (C 60/C 70). The rate constants (k et) and quantum yields (Φ et) of this process have been also evaluated.
基金supported by the National Natural Science Foundation of China.
文摘Until now,column chromatography is still the chief method for separation andpurification of C<sub>60</sub>/C<sub>70</sub>.The stationary phases used in the method can either be neutralalumina,graphite,activated charcoal,or the mixture of activated charcoal and silicagel,etc.The method that uses neutral alumina as the stationary phase and hexane asthe mobile phase is the most popular and earliest used,but it has many limitations.
文摘By using a micro\|bomb calorimeter, the standard enthalpies of combustion of C 60 and C 70 have been determined to be -(25 947.1±8.5) and -(29 956.1±8.9) kJ/mol respectively. A g.l.c. analysis indicated that the amounts of residual organic solvents in the samples were very small, and their effects on the final results were negligible. The energy of combustion of C 60 determined in this work is in agreement in the uncertainty interval with that determined by means of traditional calorimeter using macro amount of sample. The enthalpies of formation of these two substances have been derived. The strain energies in the molecules of C 60 and C 70 were estimated by a bond energy scheme and by using corannulene as the model compound, the results estimated from different methods are very close.
文摘Fullerols of C 60 and of C 70 \ [C 60 (OH)\-\%n\%, C 70 (OH)\-\%m\%], water\|soluble fullerene derivatives, unlike some other fullerene derivatives (such as C 60 (C\-4H\-6O), C 60 (C\-3H\-7N) and C 60 [C(COOEt)\-2]\-\%x\%), do not result in excited triplet state but in ionization via monophotonic process in aqueous solutions with 248 nm laser. The quantum yields of formation of hydrated electron ( Φ e - ) are determined to be 0.08 and 0.11 for fullerols of C 60 and of C 70 respectively at room temperature (ca. 15℃) with KI solution used as reference. By laser flash photolysis and oxidation of sulfate radical anion SO -· \-4, the fullerol radical cation or neutral radical of C 60 is confirmed to be existent and the transient absorption spectra of fullerol radical cation of C 70 are observed for the first time.
基金Project supported by the National Natural Science Foundation of China.
文摘The spectra of Cm and Cm thin films over a wide energy range (0.6 to 6.5eV) are measured by transmission spectroscopy and photothermal deflection spectroscopy (PDS), and the optical absorption coefficients are obtained. The optical transitions for the Cm and Cw thin films are analyzed according to the molecular orbital model. The weak absorption spectra of the fullerenes are similar to that of amorphous silicon. The optical energy gaps are given by Tauc’s plots as 1.75 and 1.65eV for C60 and C70 thin films, respectively. The disorders in the fullerene films, which resulted in band-tail state or defect state, are indicated by Urbach edge and sub-gap absorption. It is the disorder that brought the difficulty in determination of the energy gap for fullerenes. The effects of the deflection medium and substrate on the weak absorption spectra of fullerene films are also discussed.
文摘The photoinduced electron-transfer reaction of N,N,N′,N′-tetra-(p-methylphenyl)-4,4′-diamino-1,1′-diphenyl ether (TPDAE) and fullerenes (C 60/C 70) by nanosecond laser flash photolysis occurred in benzonitrile. Transient absorption spectral measurements were carried out during 532 nm laser flash photolysis of a mixture of the fullerenes (C 60/C 70) and TPDAE. The electron transfer from the TPDAE to excited triplet state of the fullerenes (C 60/C 70) quantum yields and rate constants of electron transfer from TPDAE to excited triplet state of fullerenes (C 60/C 70) in benzonitrile have been evaluated by observing the transient absorption bands in the near-IR region where the excited triplet state, radical anion of fullerenes (C 60/C 70) and radical cations of TPDAE are expected to appear.
