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By combining a pulsed are cluster ion source with a reflection time-of-flight mass spectrometer, we have produced and detected in situ fullerene cations as well as vanadium-carbon cluster cations. The cluster arrival time distributions favor the `'fullerene road'' mechanism for fullerene growth. The formation of fullerene cations was found to be strongly dependent on the discharge and nozzle conditions. Fullerene C-60(+)/C-70(+) were preferentially produced by optimizing these conditions. Vanadium-carbon cluster cations were produced and detected by using a composite electrode (V2O5/graphite). While the metallocarbohedrene V8C12+ could be produced with a reasonable it intensity, it was not dominant under our experimental conditions. (C) 1996 American Institute of Physics. these conditions.

Reaction of excimer laser (XeCl, 308 nm) vaporized and excited fullerenes with La was carried out in a mixture of fullerenes and La2O3. The reaction products La@C-60, La@(60-2n), and La@C-60+2m, were identified by a reflectron-type time-of-flight mass spectrometer (RTOFMS). The endohedral nature of these metallofullerenes is discussed in terms of a `'window'' mechanism. As an initial effort, a macroscopic amount of La@C-2n, was also collected by this method and confirmed by laser-desorption time-of-flight mass analysis.

Reaction of excimer laser (XeCl, 308 nm) vaporized and excited fullerenes with La was carried out in a mixture of fullerenes and La2O3. The reaction products La@C-60, La@(60-2n), and La@C-60+2m, were identified by a reflectron-type time-of-flight mass spectrometer (RTOFMS). The endohedral nature of these metallofullerenes is discussed in terms of a `'window'' mechanism. As an initial effort, a macroscopic amount of La@C-2n, was also collected by this method and confirmed by laser-desorption time-of-flight mass analysis.

By combining a pulsed are cluster ion source with a reflection time-of-flight mass spectrometer, we have produced and detected in situ fullerene cations as well as vanadium-carbon cluster cations. The cluster arrival time distributions favor the `'fullerene road'' mechanism for fullerene growth. The formation of fullerene cations was found to be strongly dependent on the discharge and nozzle conditions. Fullerene C-60(+)/C-70(+) were preferentially produced by optimizing these conditions. Vanadium-carbon cluster cations were produced and detected by using a composite electrode (V2O5/graphite). While the metallocarbohedrene V8C12+ could be produced with a reasonable it intensity, it was not dominant under our experimental conditions. (C) 1996 American Institute of Physics. these conditions.

Reaction of excimer laser (XeCl, 308 nm) vaporized and excited fullerenes with La was carried out in a mixture of fullerenes and La2O3. The reaction products La@C-60, La@(60-2n), and La@C-60+2m, were identified by a reflectron-type time-of-flight mass spectrometer (RTOFMS). The endohedral nature of these metallofullerenes is discussed in terms of a `'window'' mechanism. As an initial effort, a macroscopic amount of La@C-2n, was also collected by this method and confirmed by laser-desorption time-of-flight mass analysis.

By combining a pulsed are cluster ion source with a reflection time-of-flight mass spectrometer, we have produced and detected in situ fullerene cations as well as vanadium-carbon cluster cations. The cluster arrival time distributions favor the `'fullerene road'' mechanism for fullerene growth. The formation of fullerene cations was found to be strongly dependent on the discharge and nozzle conditions. Fullerene C-60(+)/C-70(+) were preferentially produced by optimizing these conditions. Vanadium-carbon cluster cations were produced and detected by using a composite electrode (V2O5/graphite). While the metallocarbohedrene V8C12+ could be produced with a reasonable it intensity, it was not dominant under our experimental conditions. (C) 1996 American Institute of Physics. these conditions.

Reactions of excimer laser (XeCl, 308 nm) vaporized and excited fullerene C60 with La, Y, Eu, and Gd were carried out in mixtures of C 60/La2O3, C60/Y2O 3, C60/Eu2O3, and C 60/Gd2O3. The reaction products M@C 60, M@C60-2n and M@C60+2m (M=La, Y, Eu, and Gd) were identified by a reflectron type time-of-flight mass spectrometer (RTOFMS). The products were subjected to reactions with H2O, O2, and N2O in a pick-up source. The metallofullerenes were found to be nonreactive toward H2O, N2O, and O2. This gives support to the endohedral nature of the metallofullerenes. © 1995 American Institute of Physics.

Reaction of laser-generated metal cations (Fe+ and LaO+) with methanol clusters was studied in a molecular beam. The reaction products were analyzed by a time-of-flight mass spectrometer. A general reaction pattern is that of the methanol-methanol reaction which produces ether and water and which is induced by collision with the metal cations. However, very different reaction behaviors were found for Fe+ and LaO+. For Fe+, there was a critical size (n greater than or equal to 12) for the reaction of methanol clusters (CH3OH)(n), with ether loss and H2O retention. On the other hand, for LaO+, this critical size was 2, and the result was H2O loss and ether retention. Multiple-ether formation was identified in a narrow cluster size region with the number of MeOHs ranging from 2 to 4. Furthermore, the series corresponding to LaO+(MeOH)(n) or LaO+(Me(2)O)(MeOH)(n-2)(H2O) suddenly appeared for n greater than or equal to 12. The two different reaction patterns are discussed in terms of electrostatic and covalent effects in the presence and absence of a solvation shell, respectively.

The reaction of molecular oxygen clusters with laser-ablated (308 nm) hot fullerenes was studied in a molecular beam/time-of-flight mass spectrometer. Molecular oxygen cluster anions (O-2)(n)(-) were efficiently produced with n ranging from 1 to 15. The cluster anion formation is mainly attributed to the electron transfer from hot fullerenes (perhaps the fullerene molecular Rydberg states) to the oxygen clusters. The reaction of oxygen with the fullerenes also resulted in the formation of small carbon cluster anions (n = 3-20) and C60O-, C58O-, C70O- and C68O-. Among the fullerene oxide anions formed, C58O- and C68O- were dominant. O-2(-) was shown to activate the fullerene disintegration to form small carbon cluster anions.

By laser ablation of a metal target (Zn, Mg or Gd) near the stream of a supersonic expansion, molecular oxygen cluster anions (O-2)(n)(-) were efficiently produced with n in the range of 1-20 or more. The cluster anions were analysed by a time-of-flight mass spectrometer. Molecular cluster anion formation is attributed to low-energy electron attachment and high-Rydberg-state electron transfer. In the case of Gd, the addition products Gd(O-2)(n)(-) and Gd-2(O-2)(n)(-) were also observed. These products are thought to originate from ion-molecule association reactions.

Reaction of laser-generated metal cations (Fe+ and LaO+) with methanol clusters was studied in a molecular beam. The reaction products were analyzed by a time-of-flight mass spectrometer. A general reaction pattern is that of the methanol-methanol reaction which produces ether and water and which is induced by collision with the metal cations. However, very different reaction behaviors were found for Fe+ and LaO+. For Fe+, there was a critical size (n greater than or equal to 12) for the reaction of methanol clusters (CH3OH)(n), with ether loss and H2O retention. On the other hand, for LaO+, this critical size was 2, and the result was H2O loss and ether retention. Multiple-ether formation was identified in a narrow cluster size region with the number of MeOHs ranging from 2 to 4. Furthermore, the series corresponding to LaO+(MeOH)(n) or LaO+(Me(2)O)(MeOH)(n-2)(H2O) suddenly appeared for n greater than or equal to 12. The two different reaction patterns are discussed in terms of electrostatic and covalent effects in the presence and absence of a solvation shell, respectively.

Reactions of excimer laser (XeCl, 308 nm) vaporized and excited fullerene C60 with La, Y, Eu, and Gd were carried out in mixtures of C 60/La2O3, C60/Y2O 3, C60/Eu2O3, and C 60/Gd2O3. The reaction products M@C 60, M@C60-2n and M@C60+2m (M=La, Y, Eu, and Gd) were identified by a reflectron type time-of-flight mass spectrometer (RTOFMS). The products were subjected to reactions with H2O, O2, and N2O in a pick-up source. The metallofullerenes were found to be nonreactive toward H2O, N2O, and O2. This gives support to the endohedral nature of the metallofullerenes. © 1995 American Institute of Physics.

The reaction of molecular oxygen clusters with laser-ablated (308 nm) hot fullerenes was studied in a molecular beam/time-of-flight mass spectrometer. Molecular oxygen cluster anions (O-2)(n)(-) were efficiently produced with n ranging from 1 to 15. The cluster anion formation is mainly attributed to the electron transfer from hot fullerenes (perhaps the fullerene molecular Rydberg states) to the oxygen clusters. The reaction of oxygen with the fullerenes also resulted in the formation of small carbon cluster anions (n = 3-20) and C60O-, C58O-, C70O- and C68O-. Among the fullerene oxide anions formed, C58O- and C68O- were dominant. O-2(-) was shown to activate the fullerene disintegration to form small carbon cluster anions.

Reactions of excimer laser (XeCl, 308 nm) vaporized and excited fullerene C60 with La, Y, Eu, and Gd were carried out in mixtures of C 60/La2O3, C60/Y2O 3, C60/Eu2O3, and C 60/Gd2O3. The reaction products M@C 60, M@C60-2n and M@C60+2m (M=La, Y, Eu, and Gd) were identified by a reflectron type time-of-flight mass spectrometer (RTOFMS). The products were subjected to reactions with H2O, O2, and N2O in a pick-up source. The metallofullerenes were found to be nonreactive toward H2O, N2O, and O2. This gives support to the endohedral nature of the metallofullerenes. © 1995 American Institute of Physics.

The reaction of molecular oxygen clusters with laser-ablated (308 nm) hot fullerenes was studied in a molecular beam/time-of-flight mass spectrometer. Molecular oxygen cluster anions (O-2)(n)(-) were efficiently produced with n ranging from 1 to 15. The cluster anion formation is mainly attributed to the electron transfer from hot fullerenes (perhaps the fullerene molecular Rydberg states) to the oxygen clusters. The reaction of oxygen with the fullerenes also resulted in the formation of small carbon cluster anions (n = 3-20) and C60O-, C58O-, C70O- and C68O-. Among the fullerene oxide anions formed, C58O- and C68O- were dominant. O-2(-) was shown to activate the fullerene disintegration to form small carbon cluster anions.

By laser ablation of a metal target (Zn, Mg or Gd) near the stream of a supersonic expansion, molecular oxygen cluster anions (O-2)(n)(-) were efficiently produced with n in the range of 1-20 or more. The cluster anions were analysed by a time-of-flight mass spectrometer. Molecular cluster anion formation is attributed to low-energy electron attachment and high-Rydberg-state electron transfer. In the case of Gd, the addition products Gd(O-2)(n)(-) and Gd-2(O-2)(n)(-) were also observed. These products are thought to originate from ion-molecule association reactions.

Reaction of laser-generated metal cations (Fe+ and LaO+) with methanol clusters was studied in a molecular beam. The reaction products were analyzed by a time-of-flight mass spectrometer. A general reaction pattern is that of the methanol-methanol reaction which produces ether and water and which is induced by collision with the metal cations. However, very different reaction behaviors were found for Fe+ and LaO+. For Fe+, there was a critical size (n greater than or equal to 12) for the reaction of methanol clusters (CH3OH)(n), with ether loss and H2O retention. On the other hand, for LaO+, this critical size was 2, and the result was H2O loss and ether retention. Multiple-ether formation was identified in a narrow cluster size region with the number of MeOHs ranging from 2 to 4. Furthermore, the series corresponding to LaO+(MeOH)(n) or LaO+(Me(2)O)(MeOH)(n-2)(H2O) suddenly appeared for n greater than or equal to 12. The two different reaction patterns are discussed in terms of electrostatic and covalent effects in the presence and absence of a solvation shell, respectively.

The reaction of excimer laser (XeCl, 308 nm ) vaporized and excited fullerene C-60 With La was carried out in a mixture of C-60 and La2O3. The reaction products La@C-60, La@C-60-2n and La@C-60+2m were identified by a reflectron type time-of-flight mass spectrometer (RTOFMS). This work provides a first experimental evidence of endohedral metallofullerene formation by letting a La atom penetrate into the C-60 cage through a sort of `window' mechanism.

The reaction of excimer laser (XeCl, 308 nm ) vaporized and excited fullerene C-60 With La was carried out in a mixture of C-60 and La2O3. The reaction products La@C-60, La@C-60-2n and La@C-60+2m were identified by a reflectron type time-of-flight mass spectrometer (RTOFMS). This work provides a first experimental evidence of endohedral metallofullerene formation by letting a La atom penetrate into the C-60 cage through a sort of `window' mechanism.

The reaction of excimer laser (XeCl, 308 nm ) vaporized and excited fullerene C-60 With La was carried out in a mixture of C-60 and La2O3. The reaction products La@C-60, La@C-60-2n and La@C-60+2m were identified by a reflectron type time-of-flight mass spectrometer (RTOFMS). This work provides a first experimental evidence of endohedral metallofullerene formation by letting a La atom penetrate into the C-60 cage through a sort of `window' mechanism.