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Raman Spectroscopy Study of Isolated Double Wall Carbon Nanotubes with Different Metallic and Semiconducting Configurations Mildred S. Dresselhaus, Massachusetts.

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Presentation on theme: "Raman Spectroscopy Study of Isolated Double Wall Carbon Nanotubes with Different Metallic and Semiconducting Configurations Mildred S. Dresselhaus, Massachusetts."— Presentation transcript:

1 Raman Spectroscopy Study of Isolated Double Wall Carbon Nanotubes with Different Metallic and Semiconducting Configurations Mildred S. Dresselhaus, Massachusetts Institute of Technology, DMR 0704197 We have reported, for the first time, detailed Raman spectroscopy experiments carried out on individual DWNTs, where both concentric tubes are measured in resonance, in order to understand the dependence of their electronic and optical properties according to their metallic (M) and semiconducting (S) configurations. Raman spectroscopy experiments on DWNT bundles have been reported earlier, but since the Raman signal is coming from an ensemble of DWNTs with different inner/outer wall features, it had been impossible to distinguish between the individual contributions to the Raman spectra from each of the four possible DWNT configurations (S@S, M@S, S@M and M@M). The method that we have developed for carrying out such measurements is effective in locating and identifying individual DWNTs with different inter-tube configurations and will open up a new direction for the investigation of charge transfer phenomena and layer interactions in carbon nanotubes, permitting more meaningful comparisons to the corresponding spectra in graphene. (a) The Au grid fabricated on top of a silicon substrate using e-beam lithography. (b) and (c) Raman Maps of the same spatial region showing an individual DWNT whose inner and outer constituents are in resonance with E laser =1.91eV and E laser =1.61eV, respectively. (d) The Kataura plot used to probe the M or S layers of an S@M DWNT. Red (black) circles correspond to M (S) tubes. (e) Resonance window of the (18,3) outer metallic layer (158cm -1 ) of an isolated S@M DWNT. (f) The Raman spectra of the RBM, G band and G’ band features taken from the same isolated S@M DWNT. at several E laser. (e) (d) (f)

2 Keynote Talks to Encourage Women in Science Mildred S. Dresselhaus, Massachusetts Institute of Technology, DMR 0704197 Three major keynote talks were given this year by the PI to encourage women in science: at the University of Michigan (January 19), Rensselaer Polytechnical University (April 2), and Tufts University (April 4). Studies show that women students are encouraged by meeting their peers, meeting role models, hearing about exciting research being done by women, and learning how others have succeeded in the past, presenting posters on their own work and enjoying the whole experience. Particularly noteworthy and memorable was the student- organized Conference for Undergraduate Women in Physics held simultaneously at three locations (at Yale University, the University of Michigan, and the University of Southern California) to accommodate students from the eastern, central and western parts of the US. The PI gave the keynote talk which was simultaneously telecasted to an enthusiastic audience at the three locations (including the question and answer session). Also featured were exciting talks by women faculty about their research, and posters were presented by the undergraduates about their own undergraduate projects. The main thrust of these meetings was to encourage undergraduate women to pursue graduate studies in physics or to use their undergraduate experience to branch out into other fields of science and engineering.


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