Vibrational spectroscopy of C60

Abstract

The fullerene era was started in 1985 with the discovery of the stable C 60 cluster and its interpretation as a cage structure with the familiar shape of a soccer ball [1]. An explosive growth in fullerene research was triggered in 1990 by the development of a method to produce fullerenes in bulk quantities [2]. Subsequently, the structural, electronic, and vibrational properties of many fullerenes have been studied in detail. The importance and potential of this new class of materials is exemplified by the discovery of intermediatetemperature superconductivity in doped C 60 [3]. Carbon nanotubes, a novel form of carbon which combines the properties of graphite and fullerenes, were discovered in 1991 [4]. Because of their intriguing properties and potential for applications, nanotubes are currently the subject of very intense research. Polymerization of C 60 molecules, particularly by photoexcitation [5] but by several other techniques as well, also results in a variety of interesting new structures, which contain both 4-coordinated and 3-coordinated carbon atoms [6]. The burgeoning field of fullerene research has been reviewed by several authors [7][8][9][10][11][12], most notably by Dresselhaus et al. [11] in an extensive monograph that appeared in 1996.In spite of the rapidly increasing interest in new forms of fullerenes, icosahedral C 60 , the "most beautiful molecule" [13], remains the focus of vigorous research as the prototype fullerene system. The present chapter concerns the vibrational structure of C 60 and the efforts to unravel its details using spectroscopic techniques. This remains a work in progress, but we hope to show that a look at the existing body of experimental and theoretical research from the broader perspective of an extended article provides a deeper understanding of the vibrational properties of C 60 .

Theoretical Raman fingerprints ofα-,β-, andγ-graphyne

“…14 The relative deviation of the NTB phonon frequencies with respect to the reported ones for C 60 (Ref. 15) increases with increasing frequency up to about 1000 cm −1 but remains almost constant in the high-frequency region above 1000 cm −1 . Agreement of the calculated frequencies with the reported ones can be achieved by appropriate scaling of the former.…”

Theoretical Studies of Raman Spectra for Planar Polymerized C60

“…In comparing these spectra, one must take into account our known frequency discrepancies for I h C 60 , which are discussed in detail in Ref. [19]. Qualitatively, at the lower frequencies, our calculated I h C 60 frequencies tend to be 1% to 5% low, with a maximum discrepancy of À4.9% for H g (1); at higher frequencies, our calculated I h C 60 frequencies tend to be 5% to 10% high, with a maximum discrepancy of þ9.3% for A g (2).…”

“…The eigenvector expansions for each of these peaks is given in Table 1 pancies for these various parent modes vary between þ5% and þ9% (see Ref. [19] for details), our discrepancies in the frequencies of these polymer modes can be expected to have a variation of the same order of magnitude. Since 4% of 1600 cm À1 is 64 cm À1 , we should not compare downshifts for the A g (2)-derived mode of two polymers if their secondary parent symmetries are quite different.…”

Assembly of Gold Nanoparticles Mediated by Multifunctional Fullerenes

“…These two bands can be assigned to the A g (2) mode (1448 cm -1 ) and H g (8) mode (1561 cm -1 ) for the Raman-active vibration modes of C 60 . 37,38 The detection of SERS for these two bands is clearly due to the surface effect of the gold nanoparticles, a strong piece of evidence supporting the adsorption of MPF on the surfaces of gold nanoparticles which is responsible for the MPF-Au nm assembly. Figure 11 shows a representative set of SERS spectra for the solution-phase samples.…”