Quantum spin dynamics

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Electron spin ensemble strongly coupled to a three-dimensional microwave cavity

APPLIED PHYSICS LETTERS 98:25 (2011) ARTN 251108

Authors:

Eisuke Abe, Hua Wu, Arzhang Ardavan, John JL Morton
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Photochemical stability of N@C60 and its pyrrolidine derivatives

CHEMICAL PHYSICS LETTERS 508:4-6 (2011) 187-190

Authors:

Guoquan Liu, Andrei N Khlobystov, Arzhang Ardavan, G Andrew D Briggs, Kyriakos Porfyrakis
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Electron paramagnetic resonance investigation of purified catalyst-free single-walled carbon nanotubes.

ACS Nano 4:12 (2010) 7708-7716

Authors:

Mujtaba Zaka, Yasuhiro Ito, Huiliang Wang, Wenjing Yan, Alex Robertson, Yimin A Wu, Mark H Rümmeli, David Staunton, Takeshi Hashimoto, John JL Morton, Arzhang Ardavan, G Andrew D Briggs, Jamie H Warner

Abstract:

Electron paramagnetic resonance of single-walled carbon nanotubes (SWCNTs) has been bedevilled by the presence of paramagnetic impurities. To address this, SWCNTs produced by laser ablation with a nonmagnetic PtRhRe catalyst were purified through a multiple step centrifugation process in order to remove amorphous carbon and catalyst impurities. Centrifugation of a SWCNT solution resulted in sedimentation of carbon nanotube bundles containing clusters of catalyst particles, while isolated nanotubes with reduced catalyst particle content remained in the supernatant. Further ultracentrifugation resulted in highly purified SWCNT samples with a narrow diameter distribution and almost no detectable catalyst particles. Electron paramagnetic resonance (EPR) signals were detected only for samples which contained catalyst particles, with the ultracentrifuged SWCNTs showing no EPR signal at X-band (9.4 GHz) and fields < 0.4 T.
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Electron paramagnetic resonance investigation of purified catalyst-free single-walled carbon nanotubes

ACS Nano 4:12 (2010) 7708-7716

Authors:

M Zaka, Y Ito, H Wang, W Yan, A Robertson, YA Wu, MH Rümmeli, D Staunton, T Hashimoto, JJL Morton, A Ardavan, GAD Briggs, JH Warner

Abstract:

Electron paramagnetic resonance of single-walled carbon nanotubes (SWCNTs) has been bedevilled by the presence of paramagnetic impurities. To address this, SWCNTs produced by laser ablation with a nonmagnetic PtRhRe catalyst were purified through a multiple step centrifugation process in order to remove amorphous carbon and catalyst impurities. Centrifugation of a SWCNT solution resulted in sedimentation of carbon nanotube bundles containing clusters of catalyst particles, while isolated nanotubes with reduced catalyst particle content remained in the supernatant. Further ultracentrifugation resulted in highly purified SWCNT samples with a narrow diameter distribution and almost no detectable catalyst particles. Electron paramagnetic resonance (EPR) signals were detected only for samples which contained catalyst particles, with the ultracentrifuged SWCNTs showing no EPR signal at X-band (9.4 GHz) and fields < 0.4 T. © 2010 American Chemical Society.
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Quantum interference between photo-excited states in a solid-state mott insulator

Optics InfoBase Conference Papers (2010)

Authors:

S Wall, D Brida, SR Clark, HP Ehrke, D Jaksch, A Ardavan, S Bonora, H Uemura, Y Takahashi, T Hasegawa, H Okamoto, G Cerullo, A Cavalleri

Abstract:

By exciting with sub-10-fs 1.6-μm pulses the quasi-one-dimensional Mott insulator ETF2TCNQ, we observe prompt collapse of the Mott gap modulated by 24-THz oscillations of the gap, which are assigned to quantum interference between holon-doublon excitations. © 2010 Optical Society of America.