Hamburg 2009 – scientific programme
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A: Fachverband Atomphysik
A 38: Atomic Clusters IV
A 38.5: Talk
Friday, March 6, 2009, 15:00–15:15, VMP 6 HS-C
Observation of giant dipole plasmon resonance in electron spectrum from C60 in fast ion-impact — Aditya Kelkar, D. Misra, and •Lokesh C. Tribedi — Tata Institute of Fundamental Research, Colaba, Mumbai 400005, India
Fullerenes are known to exhibit collective excitation i.e., the giant dipole plasmon resonance (GDPR). The GDPR has been observed earlier in photoionization through the detection of photoions. Its effect on multiple ionization and electron capture have also been reported [1,2]. However, a direct evidence of this process in fast ion-collisions is awaited. The GDPR de-excites through the emission of electrons with a characteristic energy. This presents a unique possibility of observing the GDPR state directly in the low energy electron spectrum of C60. We measured the low energy (1-300 eV) e− DDCS spectrum from C60 in collisions with 4 MeV/u bare F ions at various angles. A careful measurement shows a broad peak like structure near the expected GDPR peak position (i.e. ℏω−Ip∼ 10 eV) in all the electron spectra taken for different angles. The distribution shows a dip around 90∘, which is in contrary to the expected behaviour in case of ion-atom collisions. The angular distribution suggests that the dipole oscillations are induced preferably along the projectile beam direction.
[1] U. Kadhane et al. Phys. Rev. Lett. 90, 093401 (2003).
[2] U. Kadhane et al. Phys. Rev. A (Rapd comm.) 75, 041201 (R) (2007).