[Aspuru-Guzik group list] Fwd: Biexciton coherences, skeleton for EFRC section.

Dear group members, This is the paper from Keith Nelson about bi-exciton coherences. Please do not further this document. ---------- Forwarded message ---------- From: Keith A Nelson <kanelson(a)mit.edu> Date: Thu, Aug 14, 2008 at 7:44 PM Subject: Re: Biexciton coherences, skeleton for EFRC section. To: Alan Aspuru-Guzik <alan(a)aspuru.com> Dear Alan, I've attached a version of the biexciton paper that we submitted to Science awhile back and that has been languishing as I have been too swamped to fix it in the way they requested, which includes making it longer and more accessible to both the nonlinear spectroscopy and semiconductor exciton communities. That said, it will likely be very accessible to you and your group members, especially if you've been looking at Graham Fleming's recent work. As for the plans for coherent experiments, I have not written them up cogently but I can describe them to you in a nutshell. Basically we can make this same class of 2D measurement on organic samples that will be fabricated in the project, e.g. multilayer J-aggregate films made by Vladimir Bulovic, so that we can see directly the dynamics of coherence and energy transport. This is important generally to provide feedback on how the fabrication is going, and more fundamentally to understand the connection between structure and dynamics. A key part of this is to look for any signs of coherence in the dynamics, similar to what Fleming has seen, evidenced in oscillatory time-dependent amplitudes of off-diagonal peaks in the 2D spectrum. We also should see the extent of inhomogeneity and how that influences the dynamics. And seeing biexciton coherences as we do in the semiconductor case could reveal higher-order electron correlations that may be important for a comprehensive description of the electronic structure. Keith At 10:39 AM 8/5/2008, you wrote: Dear Keth, This e-mail is about two things: First of all, I wanted to ask you if you could share with us your draft of your bi-exciton coherences paper. I have a couple students that would love to see your results. Of course, only if you are confortable. We won't share them with anybody. The second thing is regarding the coherence part of the proposal. Do you have any plans for a skeleton of it? If you take a shot at that, I can help you herd the appropriate people, but because I am not an MIT person, I would rather take a secondary role at the beginning of this process. I will start writing my part of it. Alan -- Alan Aspuru-Guzik Assistant Professor Department of Chemistry and Chemical Biology 12 Oxford Street Harvard University Cambridge, MA 02138 Tel: (617)384-8188 Group URL: http://aspuru.chem.harvard.edu Professor Keith A. Nelson Tel: 617-253-1423 MIT Room 6-235 Fax: 617-253-7030 Department of Chemistry Email: kanelson(a)mit.edu 77 Massachusetts Avenue http://nelson.mit.edu/ Cambridge, MA 02139 -- Alan Aspuru-Guzik Assistant Professor Department of Chemistry and Chemical Biology 12 Oxford Street Harvard University Cambridge, MA 02138 Tel: (617)384-8188 Group URL: http://aspuru.chem.harvard.edu