Prof Arzhang Ardavan

Abstract:

We have produced the fullerene dimers C120, C120O, and C120O2 by a high-speed vibration milling technique. The thermal stability of C120, C120O, and C 120O2 has been studied in the temperature range 150-350°C for up to 4 h under vacuum. The bridging oxygen atoms were found to substantially increase the stability of the fullerene dimer molecules. © 2006 American Chemical Society.

Abstract:

We report multifrequency high-field millimeter-wave magneto-optical measurements on the high-spin molecule, Cr10 (OMe) 20 (O2 CCMe3) 10. We find that at temperatures above 15 K and at magnetic fields above 6 T, the simple ESR spectrum expected for a single molecule magnet is markedly altered. Our data strongly suggest the presence of a higher spin excited state multiplet lying only about 10 K above the ground state. © 2006 The American Physical Society.

Abstract:

Over the past 50 years, electron-nuclear double resonance (ENDOR) has become a fairly ubiquitous spectroscopic technique, allowing the study of spin transitions for nuclei which are coupled to electron spins. However, the low spin number sensitivity of the technique continues to pose serious limitations. Here we demonstrate that signal intensity in a pulsed Davies ENDOR experiment depends strongly on the nuclear relaxation time T(1n), and can be severely reduced for long T(1n). We suggest a development of the original Davies ENDOR sequence that overcomes this limitation, thus offering dramatically enhanced signal intensity and spectral resolution. Finally, we observe that the sensitivity of the original Davies method to T(1n) can be exploited to measure nuclear relaxation, as we demonstrate for phosphorous donors in silicon and for endohedral fullerenes N@C(60) in CS(2).

Abstract:

Over the past 50 years, electron-nuclear double resonance (ENDOR) has become a fairly ubiquitous spectroscopic technique, allowing the study of spin transitions for nuclei which are coupled to electron spins. However, the low spin number sensitivity of the technique continues to pose serious limitations. Here we demonstrate that signal intensity in a pulsed Davies ENDOR experiment depends strongly on the nuclear relaxation time T1n, and can be severely reduced for long T1n. We suggest a development of the original Davies ENDOR sequence that overcomes this limitation, thus offering dramatically enhanced signal intensity and spectral resolution. Finally, we observe that the sensitivity of the original Davies method to T1n can be exploited to measure nuclear relaxation, as we demonstrate for phosphorous donors in silicon and for endohedral fullerenes N@ C60 in C S2. © 2006 American Institute of Physics.